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Response of a multi-stressed Mediterranean river to future climate and socio-economic scenarios
Abstract
Streams and rivers are among the most threatened ecosystems in Europe due to the combined effects of multiple pressures related to anthropogenic activities. Particularly in the Mediterranean region, changes in hydromorphology along with increased nutrient loadings are known to affect the ecological functions and ecosystem services of streams and rivers with the anticipated climate change being likely to further impair their functionality and structure. In this study, we investigated the combined effects of agricultural driven stressors on the ecology and delivered services of the Pinios river basin in Greece under three future world scenarios developed within the EU funded MARS project. Scenarios are based on combinations of Representative Concentration Pathways and Shared Socioeconomic Pathways and refer to early century (2030) and mid-century (2060) representing future climate worlds with particular socioeconomic characteristics. To assess the responses of ecological and ecosystem service indicators to the scenarios we first simulated hydrology and water quality in Pinios with a process-based model. Simulated abiotic stressor parameters (predictors) were linked to two biotic indicators, the macroinvertebrate indicators ASPT and EPT, with empirical modelling based on boosted regression trees and general linear models. Our results showed that the techno world scenario driven by fast economic growth and intensive exploitation of energy resources had the largest impact on both the abiotic status (nutrient loads and concentrations in water) and the biotic indicators. In contrast, the predicted changes under the other two future worlds, consensus and fragmented, were more diverse and were mostly dictated by the projected climate. This work showed that the future scenarios, especially the mid-century ones, had significant impact on both abiotic status and biotic responses underpinning the need for implementing catchment management practices able to mitigate the ecological threat on waters in the long-term.
... This is extremely worrying, considering that the Mediterranean basin is one of the major endemism hotspots on the planet, especially for freshwater diversity (Filipe et al., 2013;Tierno de Figueroa et al., 2013). Mediterranean riverine ecosystems are already found in a water-stressed region and present a wide range of taxa dependent on the water and microhabitats they supply (Rocha et al., 2020;Stefanidis et al., 2018) being of particular concern in any climate change scenario. ...
... However, 1 year later, de Conno et al. (2018) assessed the effectiveness of using acoustic data of multiple bat phonic groups as bioindicators and found negative relationships between trawling bat activity and different riverine habitat quality indices. All these studies have used different methods and indices to assess the utility of trawling bats as indicators, highlighting the need to select the appropriate 'measures' to develop indices of habitat integrity and quality, preferably related to already-established indices like the index of riparian quality (QBR from its Spanish acronyms) (Munné et al., 2003) or macroinvertebrate community indices (Stefanidis et al., 2018). ...
... For instance, when we applied the indicator in a ChiroRivers transect carried out at high altitudes with some turbulent waters (northwesternmost location Figure S1), we got very inconsistent and conflicting results. We encourage other research teams, naturalists and conservationists to adopt and adapt the method and apply it in their countries in order to start a pan-European monitoring programme, as it has already been done for other taxonomical groups like butterflies (van Swaay et al., 2019) or macroinvertebrates (Stefanidis et al., 2018). We acknowledge that some regional variations might hamper the broad application of the method, but slight adjustments would be enough to adapt it to any other European region. ...
Mediterranean habitats will be one of the Eurasian ecosystems more strongly affected by Climate Change, especially their riverine systems. Monitoring these ecosystems, which are endemism hotspots and extremely sensitive to changes in rain regimes and extreme weather events like droughts, is of crucial importance. Decades of citizen science projects have proven their utility in highlighting ecological shifts and conservation action priority areas. The Bat Monitoring Programme ( www.batmonitoring.org ), for instance, has already been used to develop ecological indicators to evaluate the evolution and conservation status of Mediterranean ecosystems. However, using bats as ecological indicators for aquatic ecosystems has resulted in contradicting results, making its application a little controversial. In the present study, we compared two citizen science protocols (visual counting vs. passive acoustic monitoring) used in the Bat Monitoring Programme to test the utility of trawling bats as indicators of Mediterranean riverine habitat quality at both local and landscape scales. By doing so, we aimed to build a specific ecological indicator to determine habitat quality through visual and acoustic counts. Although both protocols presented similar positive significant responses to riverine forest quality, visual counts are suggested as the best sampling approach due to their simplicity and potential within citizen science projects. Moreover, for the first time, we defined threshold values of trawling bat activity to assign different levels of habitat quality to the sampled rivers. We applied them in NE Iberia to exemplify the benefits of using them in a Mediterranean region and discussed the potential, pros and cons of these two citizen science methodologies to establish a pan‐European river biomonitoring programme using trawling bats.
... This would require the implementation of large-scale hydrologic modeling combined with scenarios that capture not only the anticipated climate change but also the socioeconomical changes such as the population growth, the land-use change, and the future water resources management scheme. Such studies are very rare and usually limited in large regions (e.g., catchments of very large rivers; e.g., see Lobanova et al., 2016;Stefanidis et al., 2018). ...
... The results of the scoping review in this chapter highlight that water assessments, which allocate water resources between human and environmental requirements, appear to ignore the fact that climate changes rapidly. Although it is common knowledge that global change models predict changes in riverine hydrology that will alter ecosystem functioning and delivery of ecosystem services at catchment scale (e.g., by 2030; see Stefanidis et al., 2018), only about 33% of the reviewed articles use climate projections in future assessments of e-flows. A smaller portion (12%) applies scenarios of management (e.g., dam operation, water abstractions, and others) to quantify the direct anthropogenic impact on the water availability and the e-flows without considering the future global change. ...
... Another issue, often overlooked, is the interactions between flow regime and water chemistry and physicochemical parameters that are inevitably influenced by the catchment's hydrology. In other words, altered flow regime will affect water quality (e.g., nutrient concentrations, oxygen saturation, and water temperature), which in turn will impact the biota (Lobanova et al., 2016;Stefanidis et al., 2018). In general, interactions between flow and flow-related factors may result in unexpected ecological responses, as many scientists have recently pointed out (Calapez et al., 2018;Graeber et al., 2017;Segurado et al., 2018) with experimental and other studies focused on multiple stressor interactions and their effects on aquatic biota. ...
... This would require the implementation of large-scale hydrologic modeling combined with scenarios that capture not only the anticipated climate change but also the socioeconomical changes such as the population growth, the land-use change, and the future water resources management scheme. Such studies are very rare and usually limited in large regions (e.g., catchments of very large rivers; e.g., see Lobanova et al., 2016;Stefanidis et al., 2018). ...
... The results of the scoping review in this chapter highlight that water assessments, which allocate water resources between human and environmental requirements, appear to ignore the fact that climate changes rapidly. Although it is common knowledge that global change models predict changes in riverine hydrology that will alter ecosystem functioning and delivery of ecosystem services at catchment scale (e.g., by 2030; see Stefanidis et al., 2018), only about 33% of the reviewed articles use climate projections in future assessments of e-flows. A smaller portion (12%) applies scenarios of management (e.g., dam operation, water abstractions, and others) to quantify the direct anthropogenic impact on the water availability and the e-flows without considering the future global change. ...
... Another issue, often overlooked, is the interactions between flow regime and water chemistry and physicochemical parameters that are inevitably influenced by the catchment's hydrology. In other words, altered flow regime will affect water quality (e.g., nutrient concentrations, oxygen saturation, and water temperature), which in turn will impact the biota (Lobanova et al., 2016;Stefanidis et al., 2018). In general, interactions between flow and flow-related factors may result in unexpected ecological responses, as many scientists have recently pointed out (Calapez et al., 2018;Graeber et al., 2017;Segurado et al., 2018) with experimental and other studies focused on multiple stressor interactions and their effects on aquatic biota. ...
... This would require the implementation of large-scale hydrologic modeling combined with scenarios that capture not only the anticipated climate change but also the socioeconomical changes such as the population growth, the land-use change, and the future water resources management scheme. Such studies are very rare and usually limited in large regions (e.g., catchments of very large rivers; e.g., see Lobanova et al., 2016;Stefanidis et al., 2018). ...
... The results of the scoping review in this chapter highlight that water assessments, which allocate water resources between human and environmental requirements, appear to ignore the fact that climate changes rapidly. Although it is common knowledge that global change models predict changes in riverine hydrology that will alter ecosystem functioning and delivery of ecosystem services at catchment scale (e.g., by 2030; see Stefanidis et al., 2018), only about 33% of the reviewed articles use climate projections in future assessments of e-flows. A smaller portion (12%) applies scenarios of management (e.g., dam operation, water abstractions, and others) to quantify the direct anthropogenic impact on the water availability and the e-flows without considering the future global change. ...
... Another issue, often overlooked, is the interactions between flow regime and water chemistry and physicochemical parameters that are inevitably influenced by the catchment's hydrology. In other words, altered flow regime will affect water quality (e.g., nutrient concentrations, oxygen saturation, and water temperature), which in turn will impact the biota (Lobanova et al., 2016;Stefanidis et al., 2018). In general, interactions between flow and flow-related factors may result in unexpected ecological responses, as many scientists have recently pointed out (Calapez et al., 2018;Graeber et al., 2017;Segurado et al., 2018) with experimental and other studies focused on multiple stressor interactions and their effects on aquatic biota. ...
Mountains and mountain rivers provide a multitude of invaluable goods and services to a profound portion of the planet’s population. As “water towers” of the Earth mountains are sources of the mightiest world rivers and play a pivotal role for global biodiversity, freshwater, and sediment supply. Distinct morphological, climatic, hydrological, hydrochemical, and biological features of mountainous river ecosystems, compared to lowland ones, make them particularly fragile and vulnerable to human interference. Despite a number of remote mountain areas and rivers still remaining intact from direct human pressures, the majority of mountain ecosystems, are being increasingly threatened by adverse local and global changes driven by market economy. To efficiently conserve and sustainably use mountain ecosystems and contribute to the survival of the planet, it is critical to change our standards and life attitudes by realizing and appreciating our immediate connection to the global ecosystem, change attitudes and current consumption patterns, and stimulate the ways our global society functions and interacts with the natural environment.
... This would require the implementation of large-scale hydrologic modeling combined with scenarios that capture not only the anticipated climate change but also the socioeconomical changes such as the population growth, the land-use change, and the future water resources management scheme. Such studies are very rare and usually limited in large regions (e.g., catchments of very large rivers; e.g., see Lobanova et al., 2016;Stefanidis et al., 2018). ...
... The results of the scoping review in this chapter highlight that water assessments, which allocate water resources between human and environmental requirements, appear to ignore the fact that climate changes rapidly. Although it is common knowledge that global change models predict changes in riverine hydrology that will alter ecosystem functioning and delivery of ecosystem services at catchment scale (e.g., by 2030; see Stefanidis et al., 2018), only about 33% of the reviewed articles use climate projections in future assessments of e-flows. A smaller portion (12%) applies scenarios of management (e.g., dam operation, water abstractions, and others) to quantify the direct anthropogenic impact on the water availability and the e-flows without considering the future global change. ...
... Another issue, often overlooked, is the interactions between flow regime and water chemistry and physicochemical parameters that are inevitably influenced by the catchment's hydrology. In other words, altered flow regime will affect water quality (e.g., nutrient concentrations, oxygen saturation, and water temperature), which in turn will impact the biota (Lobanova et al., 2016;Stefanidis et al., 2018). In general, interactions between flow and flow-related factors may result in unexpected ecological responses, as many scientists have recently pointed out (Calapez et al., 2018;Graeber et al., 2017;Segurado et al., 2018) with experimental and other studies focused on multiple stressor interactions and their effects on aquatic biota. ...
The modification of sediment and flow regimes caused by damming and river regulation has deleterious effects on the ecological and morphological river processes. This alteration of river systems triggered the implementation of safeguarding environmental flows (e-flows) defined as “the quantity, timing, and quality of water flows required to sustain freshwater and estuarine ecosystems and the human livelihoods and wellbeing that depend on these ecosystems”. In the last decades, physical habitat simulation approaches emerged as fundamental stand-alone or supplementary methods for e-flow assessment. These approaches combine three main components: (1) hydraulic simulation, (2) habitat suitability modeling, to determine the quality of the available habitat, and (3) hydrological analyses (under current and climate change scenarios). E-flow regimes are finally defined, by assessing the spatial and temporal habitat variability for the target taxa or community, after combining these three components. During the process of physical habitat simulation some river processes, such as sediment transport and morphological changes, are often neglected while uncertainties arise from every component. We reviewed the elements that should be considered in every component of the physical habitat simulation to reduce uncertainties with emphasis on the actual trends on the topic and how sediment transport and river morphodynamics can be included within this methodological framework.
... This would require the implementation of large-scale hydrologic modeling combined with scenarios that capture not only the anticipated climate change but also the socioeconomical changes such as the population growth, the land-use change, and the future water resources management scheme. Such studies are very rare and usually limited in large regions (e.g., catchments of very large rivers; e.g., see Lobanova et al., 2016;Stefanidis et al., 2018). ...
... The results of the scoping review in this chapter highlight that water assessments, which allocate water resources between human and environmental requirements, appear to ignore the fact that climate changes rapidly. Although it is common knowledge that global change models predict changes in riverine hydrology that will alter ecosystem functioning and delivery of ecosystem services at catchment scale (e.g., by 2030; see Stefanidis et al., 2018), only about 33% of the reviewed articles use climate projections in future assessments of e-flows. A smaller portion (12%) applies scenarios of management (e.g., dam operation, water abstractions, and others) to quantify the direct anthropogenic impact on the water availability and the e-flows without considering the future global change. ...
... Another issue, often overlooked, is the interactions between flow regime and water chemistry and physicochemical parameters that are inevitably influenced by the catchment's hydrology. In other words, altered flow regime will affect water quality (e.g., nutrient concentrations, oxygen saturation, and water temperature), which in turn will impact the biota (Lobanova et al., 2016;Stefanidis et al., 2018). In general, interactions between flow and flow-related factors may result in unexpected ecological responses, as many scientists have recently pointed out (Calapez et al., 2018;Graeber et al., 2017;Segurado et al., 2018) with experimental and other studies focused on multiple stressor interactions and their effects on aquatic biota. ...
In all available methodologies for the assessment of the environmental flow requirements, a sufficient knowledge of the natural hydrological regime is essential. In this chapter the hydrological data that are required in environmental flow assessment studies, their main characteristics, and their importance as well as the specific challenges in the case of mountainous areas are analyzed. The various available data sources, the measurement and processing of hydrological data, and the utilization of modeling techniques for the estimation of streamflow data in the case of ungauged or poorly gauged watersheds and for the naturalization of streamflow data are also presented. A short description of hydrological data series analysis for the determination of environmental water requirements is provided as well. Finally, sources for further reading are provided in each section.
... Climate change projections according to the most pessimistic scenario (RCP 8.5 high emissions) predict a ∼2°C rise in mean annual air temperature and a 10% decrease in annual precipitation for the Pinios Catchment by 2060 (Stefanidis et al. 2018). Assuming that projected increases in surface water temperatures are often 50-70% of the projected increases in air temperature (EEA 2008), a 2°C rise in mean annual air temperature could mean a 1.4°C rise in water temperature. ...
... Assuming that projected increases in surface water temperatures are often 50-70% of the projected increases in air temperature (EEA 2008), a 2°C rise in mean annual air temperature could mean a 1.4°C rise in water temperature. We assumed here that these changes will result in a decrease in DO concentration, as discussed in detail by Stefanidis et al. (2018). ...
... Scenarios were selected to allow visualisation around the climate change projections outlined earlier for the stressors included in the model outputs for each catchment. The assessment of climate change effects for the Pinios Catchment is based on the assumption that oxygen concentration will decrease as a result of prolonged drought periods and higher water temperatures (Stefanidis et al. 2018). The scenario ranges were Loch Leven: 0.0, −0.5, −1.0, and −1.5 mm d −1 change in growing season mean precipitation (0-60% decrease relative to mean value across data); Pinios Catchment: 0.0, −0.5, −1.5, and −2.5 mg L −1 change in autumn DO concentration (0-30% decrease); and Lepsämänjoki Catchment: 0.0, 1.0, 2.0, and 3.0°C change in mean growing season water temperature (0-17% increase). ...
Interactions between stressors in freshwater ecosystems, including those associated with climate change and nutrient enrichment, are currently difficult to detect and manage. Our understanding of the forms and frequency of occurrence of such interactions is limited; assessments using field data have been constrained as a result of varying data forms and quality. To address this issue, we demonstrate a statistical approach capable of assessing multiple stressor interactions using contrasting data forms in 3 European catchments (Loch Leven Catchment, UK: assessment of phytoplankton response in a single lake with time series data; Pinios Catchment, Greece: macroinvertebrate response across multiple rivers using spatial data; and Lepsämänjoki Catchment, Finland: phytoplankton response across multiple rivers using spatiotemporal data). Statistical models were developed to predict the relative and interactive effects of climate change and nutrient enrichment sensitive indicators (stressors) on indicators of ecological quality (ecological responses) within the framework of linear mixed effects models. In all catchments, indicators of nutrient enrichment were identified as the primary stressor, with climate change-sensitive indicators causing secondary effects (Loch Leven: additive, total phosphorus [TP] × precipitation; Pinios: additive, nitrate × dissolved oxygen; Lepsämänjoki: synergistic, TP × summer water temperature), the intensity of which varied between catchments and along the nutrient stressor gradient. Simple stressor change scenarios were constructed for each catchment and used in combination with mechanistic models to explore potential management responses. This approach can be used to explore the need for multiple stressor management in freshwaters, helping practitioners navigate a complex world of environmental change.
... Subsequently, the forecasted temperature and precipitation data derived from the Shared Socioeconomic Pathways (SSPs) scenarios were employed to inform hydrological models to ascertain future changes in comparison to a baseline period representing current conditions [27]. The SWAT model stands out as one of the prominent hydrological models extensively utilized in numerous research endeavors within this field [16,19,20,28]. ...
... Several studies indicate that climate change will have an impact on hydrological conditions and water resources [28][29][30][31][32], These alterations could potentially result in a decrease or increase in the risk of drought or flood. For instance, Meresa et al. [33] examined future shifts in mean and low flows (Q95) across 37 catchments in the Republic of Ireland, observing substantial declines in annual low flows. ...
Climate is one of the main drivers of hydrological processes, and climate change has caused worldwide effects such as water scarcity, frequent floods and intense droughts. The purpose of this study was to analyze the effects of climate change on the water balance components, high flow and low flow stream conditions in a semi-arid basin in Iran. For this reason, the climate outputs of the CanESM5 model under Shared Socioeconomic Pathways (SSP) scenarios SSP126, SSP245, and SSP585 were spatially downscaled by the Statistical Downscaling Model (SDSM). The hydrological process was simulated by the Soil and Water Assessment Tool (SWAT) model. Key findings include a 74% increase in evapotranspiration, a reduction by up to 9.6% in surface runoff, and variations in discharge by up to 53.6%. The temporal analysis of snow melting changes revealed an increase in the volume of snow melting during winter months and a reduction in the volume during spring. The projected climate change is expected to cause notable variations in high and low flow events, particularly under the SSP585 scenario, which anticipates significant peaks in flow rates. This comprehensive analysis underscores the pressing need for adaptive strategies in water resource management to mitigate the anticipated impacts of climate variability.
... Countries across the Mediterranean basin are susceptible to climate change, as water availability is expected to decrease in the future with a simultaneous expansion of aridity [1][2][3]. The climate change influences the alternation of seasons by increasing the disparity between wet and dry ones [4][5][6], while it changes the spatiotemporal distribution of precipitation, thus strongly affecting ecosystems and human activities [2,4,7]. ...
... Countries across the Mediterranean basin are susceptible to climate change, as water availability is expected to decrease in the future with a simultaneous expansion of aridity [1][2][3]. The climate change influences the alternation of seasons by increasing the disparity between wet and dry ones [4][5][6], while it changes the spatiotemporal distribution of precipitation, thus strongly affecting ecosystems and human activities [2,4,7]. This phenomenon is expected to be strong in countries such as Greece, which is characterized by large landscape variability additionally affecting the local climatic characteristics [6,8]. ...
Precipitation is one of the most variable climatic parameters, as it is determined by many physical processes. The spatiotemporal characteristics of precipitation have been significantly affected by climate change during the past decades. Analysis of precipitation trends is challenging, especially in regions such as Greece, which is characterized by complex topography and includes several ungauged areas. With this study, we aim to shed new light on the climatic characteristics and inter-annual trends of precipitation over Greece. For this purpose, we used ERA5 monthly precipitation data from 1950 to 2020 to estimate annual Theil–Sen trends and Mann–Kendall significance over Greece and surrounding areas. Additionally, in order to analyze and model the nonlinear relationships of monthly precipitation time series, we used generalized additive models (GAMs). The results indicated significant declining inter-annual trends of areal precipitation over the study area. Declining trends were more pronounced in winter over western and eastern Greece, but trends in spring, summer and autumn were mostly not significant. GAMs showcased that the trends were generally characterized by nonlinearity and precipitation over the study area presented high inter-decadal variability. Combining the results, we concluded that precipitation did not linearly change during the past 7 decades, but it first increased from the 1950s to the late 1960s, consequently decreased until the early 1990s and, afterwards, presented an increase until 2020 with a smaller rate than the 1950–1960s.
... The Mediterranean region is particularly vulnerable to climate change as future projections show an increase in aridity that will likely induce a further reduction in water availability [12][13][14]. The impact of climate change is mostly associated with changes of seasonal variability as disparity between wet and dry season is expected to increase [15][16][17]. ...
... Besides temperature and precipitation, there is growing evidence for atmospheric stilling (decrease of wind speed near surface) that influences limnological processes, mainly lake mixing and stratification [8,11]. Furthermore, future land use changes are expected to enhance the impact of climate change on inland waters, mostly because of an increase in the demand for domestic and agricultural use of water [13]. Thus, changes in the climatic conditions are very likely to affect lake productivity and water quality with possible implications for biotic communities [9,20]. ...
Climate change is known to affect world’s lakes in many ways. Lake warming is perhaps the most prominent impact of climate change but there is evidence that changes of precipitation and wind speed over the surface of the lakes may also have a significant effect on key limnological processes. With this study we explored the interannual trends of surface temperature, precipitation, and wind speed over 18 lakes of Greece using ERA5-Land data spanning over a period of almost four decades. We used generalized additive models (GAMs) to conduct time-series analysis in order to identify significant trends of change. Our results showed that surface temperature has significantly increased in all lakes with an average rate of change for annual temperature of 0.43 °C decade⁻¹. With regard to precipitation, we identified significant trends for most lakes and particularly we found that precipitation decreased during the first two decades (1981–2000), but since 2000 it increased notably. Finally, wind speed did not show any significant change over the examined period with the exception for one lake. In summary, our work highlights the major climatic changes that have occurred in several freshwater bodies of Greece. Thus, it improves our understanding on how climate change may have impacted the ecology of these important ecosystems and may aid us to identify systems that are more vulnerable to future changes.
... Mediterranean rivers have a long history of human disturbances at basin and corridor scales (Cooper et al., 2013;Klausmeyer and Shaw, 2009;Stella et al., 2013). Nutrient pollution, habitat fragmentation and alteration in hydrology are perhaps the most common issues that Mediterranean lotic systems are facing today (Filipe et al., 2013;López-Doval et al., 2013;Stefanidis et al., 2016a;Stefanidis et al., 2018;Vörösmarty et al., 2010). Specifically, changes in riverine hydromorphology along with increased nutrient loadings are known to heavily influence both the ecological integrity and the aquatic biodiversity of these systems (Bonada and Resh, 2013;Filipe et al., 2013;Gasith and Resh, 1999;Hershkovitz and Gasith, 2013;Stefanidis et al., 2016b). ...
... We were mainly interested in examining the role of hydromorphological modifications, jointly with nutrient pollution, as those two stressors are commonly considered the most prominent in lotic systems of Mediterranean catchments (Stefanidis et al., 2018). We found that hydromorphological modifications have a significant negative effect on species richness, along with phosphates, but taxonomic distinctness and compositional dissimilarity between river reaches were driven mostly by gradients of natural variability, such as the elevational gradient. ...
Aquatic and riparian plants play a crucial role in the functioning of riverine ecosystems. Hence, analyzing multiple facets of plant diversity could be extremely useful for assessing the ecological integrity of lotic ecosystems. The main objective of this study was to investigate the response of multiple facets of aquatic plant diversity, such as species richness, taxonomic distinctness and compositional dissimilarity, to environmental factors (i.e. nutrient pollution and hydromorphological alteration) in 72 stream reaches of mainland Greece.
We employed Generalized Additive Models to identify the variables with the highest influence and examine the response of species richness and taxonomic distinctness to environmental gradients. The relationship between compositional dissimilarity and the environment was examined with Generalized Dissimilarity Modelling. Our results supported our hypothesis that human disturbances play a considerable role in shaping macrophyte assemblages. In particular, phosphates and hydromorphological modification were significant predictors of species richness, whereas taxonomic distinctness was unaffected by indicators of anthropogenic stress but it was influenced mostly by elevation, water temperature and pH. Concerning the compositional dissimilarity, geographic distance, elevation, temperature and total inorganic nitrogen were the most important environmental parameters. Our findings suggest that human stressors, such as hydromorphological modification and nutrient enrichment, affect the plant species richness at stream reach scale, but when considering community composition or taxonomic distinctness, environmental factors associated with the natural variability (e.g. elevation, temperature and geographic distance) are of higher importance. Overall, our results emphasize the advantage of examining multiple aspects of diversity when designing conservation schemes and management plans for riparian areas.
... It is of interest to simulate the effect of possible changes in climate variables alongside population growth that may occur in the near future through scenario-based approaches. Scenarios were created based on the Special Report on Emission Scenarios (SRES), and RCPs of the Intergovernmental Panel on Climate Change (IPPC) coupled with some national policy measures to assess discrepancies in hydrologic components (Blanco-Gutiérrez et al., 2011;Hamlat et al., 2012;Pervez and Henebry, 2015;Abbas et al., 2016a;Adhikari and Nejadhashemi, 2016;Johannsen et al., 2016;Chattopadhyay et al., 2017;Islam et al., 2017;Pham et al., 2017;Spalding-Fecher et al., 2017;Stefanidis et al., 2018;Tiwari et al., 2018). Simulating a catchment's hydrologic response through different scenarios involves calibration and validation of the hydrologic model. ...
... Conclusively, there does not seem to be a problem of water availability in the Kaligandaki basin in this century considering a projected increase in precipitation, snowmelt, water yield, and discharge. Stefanidis et al. (2018) examined the response of a multistressed Mediterranean river to future climate and socio-economic scenarios in Europe by analyzing projected surface air temperature and precipitation produced by two climate models, GFDL-ESM2M and IPSL-CM5ALR, after applying bias correction with linear scaling from 1975-2010. Scenarios in the study were based on combinations of RCPs and Shared Socioeconomic Pathways and referred to the early century (2030) and mid-century (2060) representing future climate worlds with particular socioeconomic characteristics. ...
With growing evidence in the vulnerability of river basins to water availability due to the potential effects of climate change, managers of natural resources need tools with which can be used to predict and therefore respond to changes in those resources. Hydrologic models are the simplified conceptual representation of a part of the hydrologic cycle, and are primarily used for hydrologic prediction and understanding of the water resources systems processes. A review of some current studies that assess the impacts of climate change using Water Evaluation And Planning (WEAP) and Soil and Water Assessment Tool (SWAT) was undertaken. There is less agreement on the magnitude of change of climatic variables. Still, several studies have shown that climate change will impact the availability and demand for water resources and is likely to affect nearly every aspect of human well-being, from agricultural productivity and energy use to flood control, municipal and industrial water supply to wetlands and wildlife management. Challenges associated with earth observation and in-situ climatic data certainly represent existing research and knowledge gaps in climate change impact analysis.
... The main objectives of SWAT model development are to simulate the quality and quantity of surface and groundwater and to predict the environmental impact of land use, land management practices, and climate change [56]. Previously, numerous researchers utilized the SWAT model for hydrological modeling studies in the various basin and sub-basin scales [29,31,45,[57][58][59][60][61]. The digital elevation model (DEM) is used for watershed delineation to investigate several properties of the basin, such as soil, slope, elevation, length of flow, streams created the longest path, etc. SWAT requires specific information on water abstraction that includes climate, land use, and land cover practices, topography, and river basin management to simulate hydrological processes. ...
... The results of five GCMs under both RCPs 4.5 and RCP 8.5 scenarios, illustrates that the change in temperature and precipitation frequencies will affect the water resources and streamflow within the transboundary, directly or indirectly. Besides climate change, other anthropogenic changes can also have a significant impact on streamflow, such as future management practices and land-use change significantly influencing water availability [61,73]. ...
Water resources are highly dependent on climatic variations. The quantification of
climate change impacts on surface water availability is critical for agriculture production and flood
management. The current study focuses on the projected streamflow variations in the transboundary
Mangla Dam watershed. Precipitation and temperature changes combined with future water
assessment in the watershed are projected by applying multiple downscaling techniques for three
periods (2021–2039, 2040–2069, and 2070–2099). Streamflows are simulated by using the Soil and
Water Assessment Tool (SWAT) for the outputs of five global circulation models (GCMs) and their
ensembles under two representative concentration pathways (RCPs). Spatial and temporal changes
in defined future flow indexes, such as base streamflow, average flow, and high streamflow have been
investigated in this study. Results depicted an overall increase in average annual flows under RCP 4.5
and RCP 8.5 up until 2099. The maximum values of low flow, median flow, and high flows under RCP
4.5 were found to be 55.96m3/s, 856.94m3/s, and 7506.2m3/s and under RCP 8.5, 63.29m3/s, 945.26m3/s,
7569.8 m3/s, respectively, for these ensembles GCMs till 2099. Under RCP 4.5, the maximum increases
in maximum temperature (Tmax), minimum temperature (Tmin), precipitation (Pr), and average
annual streamflow were estimated as 5.3 �C, 2.0 �C, 128.4%, and 155.52%, respectively, up until 2099.
In the case of RCP 8.5, the maximum increase in these hydro-metrological variables was up to 8.9 �C,
8.2 �C, 180.3%, and 181.56%, respectively, up until 2099. The increases in Tmax, Tmin, and Pr using
ensemble GCMs under RCP 4.5 were found to be 1.95 �C, 1.68 �C and 93.28% (2021–2039), 1.84 �C,
1.34 �C, and 75.88%(2040–2069), 1.57 �C, 1.27 �C and 72.7% (2070–2099), respectively. Under RCP
8.5, the projected increases in Tmax, Tmin, and Pr using ensemble GCMs were found as 2.26 �C,
2.23 �C and 78.65% (2021–2039), 2.73 �C, 2.53 �C, and 83.79% (2040–2069), 2.80 �C, 2.63 �C and 67.89%
(2070–2099), respectively. Three seasons (spring, winter, and autumn) showed a remarkable increase
in streamflow, while the summer season showed a decrease in inflows. Based on modeling results,
it is expected that the ManglaWatershed will experience more frequent extreme flow events in the future, due to climate change. These results indicate that the study of climate change’s impact on
the water resources under a suitable downscaling technique is imperative for proper planning and
management of the water resources.
... The main objectives of SWAT model development are to simulate the quality and quantity of surface and groundwater and to predict the environmental impact of land use, land management practices, and climate change [56]. Previously, numerous researchers utilized the SWAT model for hydrological modeling studies in the various basin and sub-basin scales [29,31,45,[57][58][59][60][61]. The digital elevation model (DEM) is used for watershed delineation to investigate several properties of the basin, such as soil, slope, elevation, length of flow, streams created the longest path, etc. SWAT requires specific information on water abstraction that includes climate, land use, and land cover practices, topography, and river basin management to simulate hydrological processes. ...
... The results of five GCMs under both RCPs 4.5 and RCP 8.5 scenarios, illustrates that the change in temperature and precipitation frequencies will affect the water resources and streamflow within the transboundary, directly or indirectly. Besides climate change, other anthropogenic changes can also have a significant impact on streamflow, such as future management practices and land-use change significantly influencing water availability [61,73]. ...
Water resources are highly dependent on climatic variations. The quantification of climate change impacts on surface water availability is critical for agriculture production and flood management. The current study focuses on the projected streamflow variations in the transboundary Mangla Dam watershed. Precipitation and temperature changes combined with future water assessment in the watershed are projected by applying multiple downscaling techniques for three periods (2021–2039, 2040–2069, and 2070–2099). Streamflows are simulated by using the Soil and Water Assessment Tool (SWAT) for the outputs of five global circulation models (GCMs) and their ensembles under two representative concentration pathways (RCPs). Spatial and temporal changes in defined future flow indexes, such as base streamflow, average flow, and high streamflow have been investigated in this study. Results depicted an overall increase in average annual flows under RCP 4.5 and RCP 8.5 up until 2099. The maximum values of low flow, median flow, and high flows under RCP 4.5 were found to be 55.96 m³/s, 856.94 m³/s, and 7506.2 m³/s and under RCP 8.5, 63.29 m³/s, 945.26 m³/s, 7569.8 m³/s, respectively, for these ensembles GCMs till 2099. Under RCP 4.5, the maximum increases in maximum temperature (Tmax), minimum temperature (Tmin), precipitation (Pr), and average annual streamflow were estimated as 5.3 °C, 2.0 °C, 128.4%, and 155.52%, respectively, up until 2099. In the case of RCP 8.5, the maximum increase in these hydro-metrological variables was up to 8.9 °C, 8.2 °C, 180.3%, and 181.56%, respectively, up until 2099. The increases in Tmax, Tmin, and Pr using ensemble GCMs under RCP 4.5 were found to be 1.95 °C, 1.68 °C and 93.28% (2021–2039), 1.84 °C, 1.34 °C, and 75.88%(2040–2069), 1.57 °C, 1.27 °C and 72.7% (2070–2099), respectively. Under RCP 8.5, the projected increases in Tmax, Tmin, and Pr using ensemble GCMs were found as 2.26 °C, 2.23 °C and 78.65% (2021–2039), 2.73 °C, 2.53 °C, and 83.79% (2040–2069), 2.80 °C, 2.63 °C and 67.89% (2070–2099), respectively. Three seasons (spring, winter, and autumn) showed a remarkable increase in streamflow, while the summer season showed a decrease in inflows. Based on modeling results, it is expected that the Mangla Watershed will experience more frequent extreme flow events in the future, due to climate change. These results indicate that the study of climate change’s impact on the water resources under a suitable downscaling technique is imperative for proper planning and management of the water resources.
... For example, changes in precipitation patterns by affecting the hydrologic regime would influence the nutrient dynamics in the catchment. For Greece particular, modelling studies have predicted an increase of nutrient pollution by 2060 either due to socioeconomical changes, or future changes in the hydrology or both depending on the prevailed future world scenario [11]. ...
... Water managers and river scientists will have to set trade-off priorities between provision of agricultural services and improvement of water quality. With this regard, certain future socio-economic scenarios predict a decline in agricultural yield as a result of reduced water availability [11] which further complicates the decision making process for a sustainable management. Undoubtedly, sustainable management of agro-ecological systems requires transdisciplinary approaches that integrate natural and social sciences in developing novel management schemes [52]. ...
Reduction of nutrient loadings is often prioritized among other management measures for improving the water quality of freshwaters within the catchment. However, urban point sources and agriculture still thrive as the main drivers of nitrogen and phosphorus pollution in European rivers. With this article we present a nationwide assessment of nitrogen and phosphorus loads that 18 large rivers in Greece receive with the purpose to assess variability among seasons, catchments, and river types and distinguish relationships between loads and land uses of the catchment. We employed an extensive dataset of 636 field measurements of nutrient concentrations and river discharges to calculate nitrogen and phosphorus loads. Descriptive statistics and a cluster analysis were conducted to identify commonalties and differences among catchments and seasons. In addition a network analysis was conducted and its modularity feature was used to detect commonalities among rivers and sampling sites with regard to their nutrient loads. A correlation analysis was used to identify major possible connections between types of land uses and nutrient loads. The results indicated that the rivers Alfeios, Strymonas, and Aliakmonas receive the highest inorganic nitrogen loads while the highest inorganic phosphorus loads were calculated for the rivers Strymonas, Aliakmonas, and Axios. Concerning the temporal variation of loads, inorganic nitrogen presented a peak on March and gradually declined until October when the dry period typically ends for most regions of Greece. Inorganic phosphorus loads had the highest average value in August and the lowest in October. Thus, our findings confirmed the presence of a typical seasonal variation in nitrogen loads that follows the seasonality in hydrology where high surface runoff during the wet months contribute to higher river discharges and higher nitrogen loads from the catchment. On the contrary, high phosphorus loads persisted during dry months that could be attributed to a dilution effect. Furthermore, the results imply a clear connection between agriculture and both nitrogen and phosphorus. Overall, this work presents extensive information on the nitrogen and phosphorus loads that major rivers in Greece receive that can largely aid water managers to adapt and revise basin management plans in accordance with agricultural management (e.g., which months farmers should reduce the use of fertilizers) with the purpose of meeting the environmental targets defined by the Water Framework Directive (WFD).
... Irregular rainfall patterns further exacerbate these issues by reducing pollutant dilution and increasing sediment and mineral loads in river systems (Chakrabarty and Sarma, 2011). Understanding the interactions between hydro-climatic stressors Assessment of seasonal variations in water quality and pollution sources in the coastal water bodies between Casablanca and Rabat (northwest Morocco) and anthropogenic impacts, such as mineral, organic, and nutrient pollution, is crucial for effective water resource management (Stefanidis et al., 2018;Ustaoğlu et al., 2020). Regular monitoring of water quality is essential to adapt management strategies and mitigate the impacts of these combined stressors (Barakat et al., 2016). ...
This study monitored the physicochemical and microbiological quality of six rivers in the coastal Oueds Basin between Casablanca and Rabat, Morocco, to assess seasonal variations in water quality, identify pollution sources, and evaluate the efficacy of water quality indices (CCME-WQI and WGQI) in a Moroccan context. Water quality was assessed during the dry and wet seasons (March and September 2024) using fifteen parameters: Temperature, pH, EC, Turbidity, DO, COD, BOD5, TP, NH4+, TKN, TSS, NO3-, Cl-, SO42- and FC. Water quality was classified as "poor" to "very poor" across all stations. The dry season showed particularly severe organic pollution (BOD₅ reaching 58.04 mg/L; COD up to 222.58 mg/L) and fecal contamination, primarily from untreated domestic wastewater and industrial discharges. Elevated ionic concentrations (Cl⁻ 4133 mg/L; SO₄²⁻ 255.3 mg/L) indicated significant agricultural and industrial runoff impacts. Intermittent streams exhibited extreme sediment loads (TSS >600 mg/L) following seasonal rewetting.This study presents the first comparative analysis of water quality index (WQI) performance in one of Morocco’s most heavily polluted downstream reaches. The findings contribute to this growing body of research using WQI, while awaiting the development of a Morocco-specific WQI framework that considers hydro-climatic variability and anthropogenic pressures.
... This is most likely due to decreasing runoff, while input from nutrient sources (i.e., agricultural fields) is projected to be constant or to increase, which ultimately leads to increasing concentrations. This is expected to lead to increasing water quality issues, including deteriorating impacts on aquatic ecology (Stefanidis et al. 2018;Vagheei et al. 2023). However, at the same time, total nutrient loads are projected to decrease due to decreasing runoff, including decreasing phosphorus and nitrate loads (Table S11). ...
Water resources are becoming increasingly scarce in the Mediterranean Basin due to climate change. Through a systematic review of 262 catchment‐based Mediterranean studies, we provide improved and detailed indications that runoff is projected to decrease by 19%, with increasing severity towards the end of the century and with increasing emission scenarios (up to −39%). We also show negative consequences for other water resources (soil moisture, aquifer recharge, irrigation demand), hydrological extremes (low flows), and water and soil quality (nutrient concentration, soil salinity, soil erosion), with negative impacts on rainfed and irrigated agriculture in the Mediterranean Basin. To protect water security, climate change adaptation aiming at more efficient water use and water retention in soils will be needed. While these adaptation measures have the potential to reverse the impacts of climate change, they may reduce downstream water availability and may be insufficient under extreme climate conditions.
... Several recent exercises in hydrologic modelling and analysis show the urgent need for adaption in the water sector. Studies overwhelmingly show that throughout the EMME region changes in precipitation are magnified in water resources, causing hydrologic droughts, reducing streamflow and groundwater recharge, amplifying water-quality problems, and resulting in dramatic increases in reservoir risk levels for water supply and 3. Water resources in relation to climate change: a review | 11 energy production, (e.g., Abbas et al., 2018Abbas et al., , 2019Abdullah and Omari, 2008;Al-Hasani, 2019;Mimikou and Baltas, 2013;Rabi et al., 2003a and2003b;Qatarneh et al., 2018;Stefanidis et al., 2018). ...
This report surveys the state of water resources in the Eastern Mediterranean and Middle East (EMME) and the challenges imposed by climate change on a water-scarce region. Reviewing national climate change adaptation strategies and evaluating the effectiveness of water-related adaptation policies and measures across the countries of the region, the report identifies gaps in research, policy and knowledge related to climate adaptation in the water sector. Hydrologic modelling studies demonstrate that reduced rainfall, higher temperatures and greater evaporative demand will increase water-supply risks and water-quality problems.
The climate adaptation measures of national adaptation strategies and plans reveal a good understanding of these threats, but implementation and financing have not kept pace. The report applies a conceptual framework for achieving climate resilience and water security in the region, which recognises the systemic aspects of climate change, water scarcity and shared water resources in the region. The framework’s six lines of action for climate resilience and water security are governance; regional cooperation; finance; research and technology; reconstruction and resilience; and capacity development. Research initiatives should consider the application of the climate-water-energy-food nexus for improving water governance and achieving climate resilience and water security.
... Despite increased efforts to study and restore perennial, intermittent rivers and ephemeral streams (PIRES) in the Mediterranean (e.g., Hershkovitz and Gasith 2013;Kaletová et al. 2019;Skoulikidis et al. 2017), many are still threatened by reduced flow rates, hydrologic and geomorphic alteration, and nutrient pollution, which lead to heavily degraded aquatic biodiversity (Carpenter et al. 1998;Rost et al. 2008;Stefanidis, Panagopoulos, and Mimikou 2018;Steffen et al. 2015). The negative effect of intensive agriculture is amplified in Mediterranean watersheds characterized by an inherent variability of rainfall and flow regimes (Gasith and Resh 1999;Gutierrez-Jurado et al. 2021). ...
Degraded water quality is one of the well‐documented adverse effect of intensive agriculture on the riverine environment. It can result from nutrient leaching from agricultural fields, stream flow harvesting, irrigation with treated wastewater, full or partial damming, and cultivating the riparian zone. The weight of each cause on the regime water quality is only sometimes apparent. Thus, stream restoration planning requires understanding of the dynamics of water quality, and stakeholders' efforts do not address the right stressors on time. This is further exacerbated in Mediterranean agriculture catchments, which are prone to water scarcity, seasonal rainfall and streamflow variations. We therefore aim to evaluate how monitoring water quality parameters can help direct river restoration projects in Eastern Mediterranean watersheds. The present project focused on water quality dynamics along the main channel of the Nahalal stream and employed high spatiotemporal monitoring of basic water quality parameters: pH, electrical conductivity (EC), and macro‐nutrients in the context of (1) spatial gradients: Channel upstream vs. downstream; (2) seasonality: Base flow vs. flood water flows; and (3) hydraulic constraint: open vs. closed channel sluice gate. The results from the systematic stream grab water sampling, 34 times over two years at 13 locations, revealed increased concentrations at the downstream direction by dry‐wet conditions prior to the date of sampling. Contrary to expectations, higher concentrations of nitrates were found upstream near a spring—a source for base flow, than at the downstream reach, and the opposite trend was found for P concentrations. The results suggest that combined effects of several stressors control stream water quality dynamics: Riparian vegetation dominated by Phragmites australis , soil‐erosion processes, and water resources management. Lack of high spatiotemporal monitoring could result in misinterpretation of the intervention actions needed at the channel and watershed scales and may lead to poor initiation of self‐stream restoration ecology.
... Global warming and climate change mainly caused by radiative forcing of human induced greenhouse gas emissions are among the most important scientific issues for the last few decades. According to the Intergovernmental Panel on Climate Change (IPCC 2007), the main threat of climate change consists of rising temperatures, persistent drought, melting glaciers and more frequent extreme weather patterns that affect strongly the human wellbeing, and the sustainable development by declining water resources availability, reducing agricultural yield, harming food security and destroying the natural ecosystems (Kim et al. 2013;Huang et al. 2016;Stefanidis et al. 2018;Kang et al. 2022;Storms et al. 2022). Mediterranean countries, and particularly semiarid and arid regions are one of the most vulnerable areas to climate change, given that, poor water management, water resources scarcity and the growing population, exacerbate strongly water stress (Erol and Randhir 2012;Milano et al. 2012;Kim et al. 2019;Linares et al. 2020). ...
Climate change is one of the most important global challenges of this century, with significant impacts on water resources, economic development and ecological health. This study aimed to investigate the effect of climate change on streamflow in Joumine watershed, upstream the Ichkeul Lake, a RAMSAR wetland and the most productive ecosystems in Tunisia and the Mediterranean. The hydrologic response of the basin was simulated based on Hydrologic Modelling System HEC-HMS. Climate data were generated from the emission scenarios RCP4.5 and RCP8.5 from the Irish Regional Climate Model (RCM) for the periods 2030–2060 and 2061–2100. The statistical analysis showed that model performance is satisfactory, with Nash–Sutcliffe efficiency of 0.7 and 0.64 for calibration and validation, respectively. The climate projections exhibited a declining trend in precipitation during the two future periods with more frequent extreme rainfall events in dry season and a rise in temperature which is more accentuated during the period 2061–2100. Climate change is expected to have profound impacts on water resources and resilience of ecosystems. Results showed that Joumine basin is projected to experience reduction in streamflow which is more pronounced under RCP8.5. The frequency and magnitude of hydrological extremes are expected to be intensified, notably during the far future period, leading to pressure on water availability in the end of the twenty-first century. Hence, sustainable water resources management is needed to close the water demand and supply gap in the Joumine river basin.
... For all the above reasons, the ecological status of the local water bodies was impacted negatively. The local River Basin Management Plan (SSW, 2014) and relevant publications (Stefanidis et al., 2018;Psomas et al., 2017;Panagopoulos et al., 2014) provide a detailed insight into the environmental status and challenges. ...
The concept of water–energy–land–food nexus highlights the complex and interrelated nature of the relevant resource systems, calling for systemic approaches, enhanced coordination of their interactions, and integration of efforts. Managing agricultural water in the context of nexus is challenging, because the management needs to meet multiple, potentially incommensurable and conflicting goals, such as water security, food security, energy security, environmental protection, economic growth, and social inclusion. This publication focuses on the use of MCDA approaches for the decision problem of agricultural water management in the context of nexus, taking into account relevant literature on MCDA applications in water and agricultural management. The proposed MCDA framework includes an additive value model, which is estimated by using the Multi-Attribute Value/Utility Theory (MAVT/MAUT) approach for the construction of marginal utility functions with the Multicriteria Interactive Intelligence Decision Aiding System (MIIDAS), and the Weights Assessment through Prioritisation (WAP) method for the estimation of the points of view and criteria weights with the WAP software. Preference elicitation and modelling includes strong interaction with an expert decision-maker (DM). Robustness analysis tools are applied to ensure that the final value system is robust and the DM is satisfied with the modelled preferences. The proposed framework is demonstrated in an agricultural river basin from Greece to showcase its relevant merits and identify its weak points. The analysis of the results from the demonstration case leads to the identification of key trade-offs for agricultural water management.KeywordsAgricultureWater managementWELFNexusDecision-makingMCDAMAUTWAPSWAT
... European rivers are threatened by multiple anthropogenic stressors that occur at various spatial scales (Cooper et al., 2013;Grill et al., 2019;Jorda-Capdevila et al., 2019;Kattel, 2019). Hydromorphological alteration and physicochemical degradation are the most common pressures that lotic systems are facing today, affecting the aquatic biodiversity and ecosystem functions (Branco et al., 2016;Filipe et al., 2013;Grizzetti et al., 2017;Lemm et al., 2021;L opez-Doval et al., 2013;Stefanidis et al., 2018). To fight this, the Water Framework Directive (WFD) 2000/60/EC, being the cornerstone of European Union's water policy, aims to protect all the surface waters, including rivers, by assessing their ecological status and thereby providing a better basis for promoting and applying mitigation and restoration measures (Carvalho et al., 2019;Giakoumis & Voulvoulis, 2018). ...
Stream geodiversity is a novel concept that is used to describe the variety of geological, geomorphological and hydrological features at a reach‐scale level. In this study, we investigated the relationship between geodiversity and ecological indicators based on fishes, benthic macroinvertebrates and diatoms used for the ecological classification of rivers in line with the Water Framework Directive (WFD) 2000/60/EC. We examined whether geodiversity can be used as a proxy indicator of ecological quality, and we further tested if geodiversity can explain a significant amount of taxa richness variation. We hypothesized that undisturbed or minimally disturbed rivers will be more hydrologically and geomorphologically diverse, and as such, the ecological quality of streams will improve with geodiversity. We also attempted to quantify the probability of achieving ‘good’ ecological quality in relation to geodiversity levels through ordinal regression analysis. Although we did not find a significant relationship between geodiversity and taxonomic richness for any of the three freshwater groups, our results showed positive effects of geodiversity on all three ecological indicators. We also found that the likelihood of achieving the WFD target increases significantly with higher geodiversity. Our findings indicate that geodiversity can potentially serve as a proxy of ecological quality and highlight the need to consider the inclusion of geodiversity measures in ecological quality assessment systems.
... This is another factor that may impact water availability and river discharge. It is noteworthy that several studies have shown that the water resources will probably continue the decreasing trend in the future, causing amplification of droughts and aridity [13][14][15][16]. ...
Climate change has influenced the discharge regime of rivers during the past decades. This study aims to reveal climate-induced interannual trends of average annual discharge and discharge maxima in a Mediterranean river from 1981 to 2017. To this aim, the Pinios river basin was selected as the study area because it is one of the most productive agricultural areas of Greece. Due to a lack of sufficient measurements, simulated daily discharges for three upstream sub-basins were used. The discharge trend analysis was based on a multi-faceted approach using Mann-Kendall tests, Quantile-Kendall plots, and generalized additive models (GAMs) for fitting non-linear interannual trends. The methodological approach proposed can be applied anywhere to investigate climate change effects. The results indicated that the average annual discharge in the three upstream sub-basins decreased in the 1980s, reaching a minimum in the early 1990s, and then increased from the middle 1990s to 2017, reaching approximately the discharge levels of the early 1980s. A more in-depth analysis unraveled that the discharge maxima in September were characterized by statistically significant increasing interannual trends for two of the three sub-basins. These two sub-basins are anthropogenically low affected, thus highlighting the clear impact of climate change that may have critical socioeconomic implications in the Pinios basin.
... A sub optimal organisation of irrigation systems [20,21] and unsustainable water resources management practices [22] have deteriorated the already disturbed water balance and accelerated the degradation of water resources in previous decades. This study additionally aims to: (a) supplement and add to the existing diverse assessment studies and data provided by model implementations in the whole PRB, its sub-catchments, groundwater bodies, and other administrative sub-areas, e.g., as described in [23][24][25][26][27][28]; and (b) facilitate the implementation of sustainable water resources management practices. ...
Robust assessments of variations in freshwater availability are essential for current and future water resource management in the Pinios River Basin (PRB), which is one of the most productive basins of Greece in terms of agriculture. To support sustainable water resources management in the PRB, we set up and calibrated the mGROWA hydrological model at a high spatial (100 m) and temporal (daily) resolution for the period 1971–2000, with particular attention given to deriving crop-specific irrigation requirements. We developed and implemented a comprehensive methodological framework to overcome data scarcity constraints in the PRB, thus enabling the derivation of high-resolution spatially continuous estimates of many input variables required for the mGROWA model. We generated estimates of spatiotemporal variations in the water balance components actual evapotranspiration, irrigation requirements, total runoff, and groundwater recharge for the PRB. In addition, through the calculation of indices, such as the potential irrigation to groundwater recharge ratio (PIQR), we demonstrate a way to identify potential unsustainable water use in irrigated agriculture. The established mGROWA model can be used both as a hydrological reference model providing continuous decision support for water resources management, focusing on irrigation water use, and a basis for climate impact studies for the PRB.
... Nunes et al. (2017) applied SWAT to a Mediterranean basin already affected by drought stress and indicated that most simulated future scenarios that involved individual changes in climate, socio-economic conditions, and a combination of both resulted in a decline in water availability. Stefanidis et al. (2018) simulated three future world climate and socio-economic scenarios which were developed as part of the MARS project using SWAT. The findings suggest that consequently to the rise of water temperature and the decrease in nutrient loadings, a decline in the average concentration of surface dissolved oxygen is to be expected. ...
The Soil and Water Assessment Tool (SWAT) is a well-established eco-hydrological model that has been extensively applied to watersheds across the globe. This work reviews over two decades (2002–2022) of SWAT studies conducted on Mediterranean watersheds. A total of 260 articles have been identified since the earliest documented use of the model in a Mediterranean catchment back in 2002; of which 62% were carried out in Greece, Italy, or Spain. SWAT applications increased significantly in recent years since 86% of the reviewed papers were published in the past decade. A major objective for most of the reviewed works was to check the applicability of SWAT to specific watersheds. A great number of publications included procedures of calibration and validation and reported performance results. SWAT applications in the Mediterranean region mainly cover water resources quantity and quality assessment and hydrologic and environmental impacts evaluation of land use and climate changes. Nevertheless, a tendency towards a multi-purpose use of SWAT is revealed. The numerous examples of SWAT combined with other tools and techniques outline the model's flexibility. Several studies performed constructive comparisons between Mediterranean watersheds' responses or compared SWAT to other models or methods. The effects of inputs on SWAT outputs and innovative model modifications and improvements were also the focus of some of the surveyed articles. However, a significant number of studies reported difficulties regarding data availability, as these are either scarce, have poor resolution or are not freely available. Therefore, it is highly recommended to identify and develop accurate model inputs and testing data to optimize the SWAT performance.
... The abstraction of water for domestic purpose, cultivation of crops, mining, industry, energy and power generation, navigation, may lead to degradation of water quality and water quantity [3]. Excess uses of them put pressure on water resources, stresses that are likely to be provoked by the change of climatic condition [4]. ...
Vulnerability assessment as an essential part of the water resource management as water is an essential natural resource. With the increasing population and changed in climatic condition, pressure on water resources has also been increased which leads to a need for vulnerability assessments. The aim of the present is to assess the vulnerability of the Haora river basin, Tripura, India. This study assesses the vulnerability under changed climate scenario and change in urbanization with the help of Analytical Hierarchy Process (AHP) multi-criteria decision-making method (MCDM). To develop the index 11 no. of parameters has been selected and AHP has been applied to find the weights value of each of the parameters based on different criteria like climatic, and urbanization impacts. These weights values have been used to develop the indicator which represents the vulnerability index of the Haora river basin. The sensitivity analysis has also been done to see the coherency of the results. This indicator has been further used to assess the impact of climate change on the water availability.
... Especially under the extensive use of BC techniques, many studies are not aware of, or not clear about, how the quality of original climate simulations affects the reliability of hydrological impact assessments. Quite a few hydrological projections are still using GCM simulations processed only with simple interpolation and BC (e.g., Stefanidis et al. 2018;Zaman et al. 2018;Anjum et al. 2019;Haider et al. 2020), despite the apparent incompatibility in the scale of the CM and HM. Even for those using the RCM products, they might also be uncertain about how dynamical downscaling and BC are affecting the results (Maraun et al. 2010), and more collaboration and communication should be encouraged among those who produce and who use the downscaling data (Takayabu et al. 2016). ...
How the value of higher-resolution climate variables dynamically downscaled can affect the hydrological impact assessment has been a long standing issue. This study investigates the potential benefit of high-resolution climate data locally tailored over South Korea in terms of the reduction of uncertainties in hydrological projections. For this purpose, a large ensemble consisting of three Global Climate Model (GCM) projections and their dynamical downscaling products in different resolutions (i.e., 20 and 5 km), and four bias correction (BC) methods is fed into a semi-distributed hydrological model (HM) customized over Korean river basins. The in-depth comparison among the 45-members hydrological simulations proves the benefit in using high-resolution Regional Climate Model (RCM) for the runoff projections. While this study acknowledges the necessity of BC to remove the systematic bias in climate simulations, it is found that the high-resolution dynamical downscaling can significantly narrow the spread brought with different BC methods, thus reducing the uncertainty in the projected hydrological change. The projected runoff changes for both the mean of wet season and the high flows indicate that there will be an intensified runoff, especially for the extremes, over South Korea under the warming. Altogether, this study provides a valuable exploration of uncertainty reduction in hydrological projections from the perspective of resolution effect of dynamical downscaling, which is meaningful for hydroclimate studies and climate change impact assessment.
... The characteristics of river basins used in different countries are different. These include abiotic parameters (land use/land cover, soil texture, depth to bedrock, depth to the water table, recent precipitation area, total stream length, watershed shape, topographic complexity, mean elevation, mean slope [14]), as well as biotic indicators [15]. In addition to these indicators, social pressure and recovery potential were considered for the entire land area within certain administrative boundaries [16]. ...
The quantitative and qualitative depletion of water resources (both surface and groundwater) is closely related to the need to protect soils against degradation, rationalization of land use, and regulation of surface water runoff within the watershed area. Belgorod Oblast (27,100 km²), one of the administrative regions of European Russia, was chosen as the study area. It is characterized by a high activity of soil erosion (the share of eroded soils is about 48% of the total area of arable land). The development phase of the River Basin Environmental Management Projects (217 river basins from the fourth to seventh order) allowed for the proceeding of the development of an integrated monitoring system for river systems and river basin systems. The methods used to establish a geoecological network for regional monitoring include the selection and application of GIS techniques to quantify the main indicators of ecological state and predisposition of river basins to soil erosion (the share of cropland and forestland, the share of the south-oriented slopes, soil erodibility, Slope Length and Steepness (LS) factor, erosion index of precipitation, and the river network density) and the method of a hierarchical classification of cluster analysis for the grouping of river basins. An approach considering the typology of river basins is also used to expand the regional network of hydrological gauging stations to rationalize the national hydrological monitoring network. By establishing 16 additional gauging stations on rivers from the fourth to seventh order, this approach allows for an increase in the area of hydro-agroecological monitoring by 1.26 times (i.e., up to 77.5% of the total area of Belgorod Oblast). Some integrated indicators of agroecological (on the watershed surface) and hydroecological (in river water flow) monitoring are proposed to improve basin environmental management projects. Six-year monitoring showed the effectiveness of water quality control measures on an example of a decrease in the concentrations of five major pollutants in river waters.
... Efficient water resource management requires a significant capital investment in smart infrastructure, efficient treatment technologies, quantifiable indicators, and monitoring tools (Behmel et al. 2016;Platikanov et al. 2019). Studies carried out in urban areas of different regions across the globe such as the states of Arizona and California in the USA, New South Wales and Victoria in Australia, Western Cape Provinces in South Africa, and the Mediterranean coast have revealed a significant reduction in quality and quantity of their potable water resources, influenced by environmental and anthropogenic pressures (Navarro-Ortega et al. 2015;Stefanidis et al. 2018;Best 2019;Bhurtun et al. 2019). The installation of specific infrastructures has been proposed and implemented to ameliorate potable water quality and to ensure its future availability. ...
The dense and industrialized populace in the mining areas of Jharia Coalfield (JCF) is plagued by a severe shortage of water supply. The unutilized pumped out coal minewater discharges may be utilized to cater to the increasing water demand of the region but it runs the risk of getting contaminated from domestic and industrial effluents. The current study aimed to assess the suitability of augmenting underground minewater for potable purposes. For this purpose, ninety underground minewater samples collected from 15 locations across JCF for the hydrological year 2019-2020 were analysed to gain an insight on the physicochemical characteristics of the minewater using an integrated approach of standard hydrochemical methods, integrated water quality index (IWQI), heavy metal pollution index (HPI), and multivariate statistical analysis. For the minewater quality to be deemed suitable for potable purposes, both IWQI (lower than 2) and HPI (lower than 30) values were considered. IWQI values of the minewater samples from the study area ranged from 1.97 to 5.08, while the HPI values ranged from 18.40 to 53.05. The pH of the samples were found to be mildly acidic to alkaline (6.5 to 8.3) with varying total hardness (149 to 719 mg L −1), total dissolved solids (341 to 953 mg L −1), and electrical conductivity (568 to 1389 µS cm −1), reflecting heterogeneity in underlying hydrosystems, variations in geological formations, and the influence of lithogenic and anthropogenic processes on the water chemistry of the region, which was corroborated by the principal component analysis (PCA) and hierarchical cluster analysis (HCA) of the minewater samples. Two major water types of the region were identified, viz., Ca-Mg-HCO 3 and Ca-Mg-Cl-SO 4. This multiparametric approach gives a holistically accurate assessment of the minewater quality, overcoming the limitations of traditional water quality indices and facilitating time-saving and effective water management practices, and sets the foundation for augmenting minewater for potable purposes to meet increasing demands.
... The artificial permeable surface includes the roof green design, permeable road, and artificial water bodies. EIA refers to the impervious area that is directly connected to the drainage collection system through rainwater pipelines [40,41]. When compared with impervious surfaces, EIA contributes more to urban area runoff. ...
The main functions of this research are to guide the proportion of urban land that is used and the layout of the facilities on it, help understand the changes to surface runoff that are caused by land being used in urban development, and thus solve surface runoff pollution. Hangzhou City, China has been selected for the experiment, and the way in which its land is utilized as well as the grading of urban construction projects in the demonstration area are specifically analyzed. This study systematically distinguishes the definitions of impervious area based on the Sutherland equation and analyzes the impact of different impervious area subtypes on surface runoff water quality. Then, we compare the impact of impervious area subtypes with the impact of other land-use patterns on surface runoff water quality. This study shows the relationship between different land-use types and runoff water bodies: Land-use index can affect runoff water quality; Greening activities, impervious surface, and the water quality index are negatively correlated; the effective impervious area rate is positively correlated with the water quality index. The paper suggests that increasing the proportion of green spaces and permeable roads in build-up land reduces the effective impervious area (EIA) and thus controls land runoff pollution and improves runoff water quality.
... This study also projected an increase in the monthly mean streamflow in November, December and January during the NEM season. However, these previous studies have provided limited information on the projected changes in extreme flows, which is critical for decision making in local water hazard risk management and environmental protection [39] across Kelantan. In addition, the SWAT calibration and validation of KRB have been mostly limited to monthly scale assessments. ...
This study introduces a hydro-climatic extremes assessment framework that combines the latest climate simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) HighResMIP with the Soil and Water Assessment (SWAT) model, and examines the influence of the different climate model resolutions. Sixty-six hydrological and environmental flow indicators from the Indicators of Hydrologic Alteration (IHA) were computed to assess future extreme flows in the Kelantan River Basin (KRB), Malaysia, which is particularly vulnerable to flooding. Results show that the annual precipitation, streamflow, maximum and minimum temperatures are projected to increase by 6.9%, 9.9%, 0.8 °C and 0.9 °C, respectively, by the 2021–2050 period relative to the 1985–2014 baseline. Monthly precipitation and streamflow are projected to increase especially for the Southwest Monsoon (June–September) and the early phase of the Northeast Monsoon (December) periods. The magnitudes of the 1-, 3-, 7-, 30- and 90-day minima flows are projected to increase by 7.2% to 8.2% and the maxima flows by 10.4% to 28.4%, respectively. Lastly, changes in future hydro-climatic extremes are frequently quite different between the high-resolution and low-resolution models, e.g., the high-resolution models projected an increase of 11.8% in mean monthly flow in November-December-January compared to 3.2% for the low-resolution models.
... The SWAT model developed by the Agricultural Research Service of the United States Department of Agriculture (USDA-ARS) is a continuous-time, semi-distributed and physics-based water quality model (Arnold et al., 1998;Gassman et al., 2014;Romagnoli et al., 2017) for simulating hydrological cycle, plant growth cycle and transportation of sediments (Arnold et al., 1998;Pyo et al., 2019;Stefanidis et al., 2018;Wu et al., 2011). The SWAT model delineates a catchment into subbasins based on the stream network and topography and subsequently into hydrological response units (HRUs) representing different combinations of soil types, land use and slope. ...
Monitoring drought and mastering the laws of drought propagation are the basis for regional drought prevention and resistance. Multivariate drought indicators considering meteorological, agricultural and hydrological information may fully describe drought conditions. However, series of hydrological variables in cold and arid regions that are too short or missing make it difficult to monitor drought. This paper proposed a method combining Soil and Water Assessment Tool (SWAT) and empirical Kendall distribution function (KC′) for drought monitoring. The SWAT model, based on the principle of runoff formation, was used to simulate the hydrological variables of the drought evolution process. Three univariate drought indexes, namely meteorological drought (standardized precipitation evapotranspiration index; SPEI), agricultural drought (standardized soil moisture index; SSI) and hydrological drought (standardized streamflow drought index; SDI), were constructed using a parametric or non-parametric method to analyze the propagation time from meteorological drought to agricultural drought and hydrological drought. The KC′ was used to build a multivariable comprehensive meteorology–agriculture–hydrology drought index (MAHDI) that integrated meteorological, agricultural and hydrological drought to analyze the characteristics of a comprehensive drought evolution. The Jinta River in the inland basin of northwestern China was used as the study area. The results showed that agricultural and hydrological drought had a seasonal lag time from meteorological drought. The degree of drought in this basin was high in the northern and low in the southern regions. MAHDI proved to be acceptable in that it was consistent with historical drought records, could catch drought conditions characterized by univariate drought indexes, and capture the occurrence and end of droughts. Nevertheless, its ability to characterize mild and moderate droughts was stronger than severe droughts. In addition, the comprehensive drought conditions showed insignificant aggravating trends in spring and summer and showed insignificant alleviating trends in autumn and winter and at annual scales. The results provided theoretical support for the drought monitoring in the Jinta River basin. This method provided the possibility for drought monitoring in other watersheds lacking measured data.
... The RCP8.5 radiative forcing scenario has been selected to assess the climate change under the business-as-usual condition in this study. The RCPs are the radiative forcing pathways that define an emission trajectory and concentration by 2100 [30,31]. For temperature correction, climatological differences of monthly temperature between the 20th century historical reproduction data and the RCP8.5 future scenario data were quantified. ...
Climate change is increasingly sensed by nations vulnerable to water-related disasters, and governments are acting to mitigate disasters and achieve sustainable development. Uncertainties in General Circulation Models’ (GCM) rainfall projections and seamless long-term hydrological simulations incorporating warming effects are major scientific challenges in assessing climate change impacts at the basin scale. Therefore, the Data Integration and Analysis System (DIAS) of Japan and the Water Energy Budget-based Rainfall-Runoff-Inundation model (WEB-RRI) were utilized to develop an integrated approach, which was then applied to the Mahaweli River Basin (MRB) in Sri Lanka to investigate climate change impacts on its hydro-meteorological characteristics. The results for the Representative Concentration Pathway (RCP8.5) scenario from four selected GCMs showed that, with an average temperature increase of 1.1 °C over the 20 years in future (2026 to 2045), the basin will experience more extreme rainfall (increase ranging 204 to 476 mm/year) and intense flood disasters and receive sufficient water in the future climate (inflow increases will range between 11 m³/s to 57 m³/s). The socio-economic damage due to flood inundation will also increase in the future climate. However, qualitatively, the overall trend of model responses showed an increasing pattern in future meteorological droughts whereas there is uncertainty in hydrological droughts. Policymakers can utilize these results and react to implementing soft or hard countermeasures for future policymaking. The approach can be implemented for climate change impact assessment of hydro-meteorology in any other river basin worldwide.
... lake mix-layer depth). Such studies could investigate the climate change impact on lakes by either exploring historical trends (e.g. using long term time series of climate related variables combined with actual ecological measurements) or by using predictive modelling and scenarios of climate projections for predicting the future ecological response ( Stefanidis et al., 2018 ). The drawback in these studies concerns the inherent uncertainty that accompanies both the estimation of climate reanalysis variables and the predictive performance of the derived ecological models. ...
Understanding the climatic drivers of eutrophication is critical for lake management under the prism of the global change. Yet the complex interplay between climatic variables and lake processes makes prediction of phytoplankton biomass a rather difficult task. Quantifying the relative influence of climate-related variables on the regulation of phytoplankton biomass requires modelling approaches that use extensive field measurements paired with accurate meteorological observations. In this study we used climate and lake related variables obtained from the ERA5-Land reanalysis dataset combined with a large dataset of in-situ measurements of chlorophyll-a and phytoplankton biomass from 50 water bodies to develop models of phytoplankton related responses as functions of the climate reanalysis data. We used chlorophyll-a and phytoplankton biomass as response metrics of phytoplankton growth and we employed two different modelling techniques, boosted regression trees (BRT) and generalized additive models for location scale and shape (GAMLSS). According to our results, the fitted models had a relatively high explanatory power and predictive performance. Boosted regression trees had a high pseudo R² with the type of the lake, the total layer temperature, and the mix-layer depth being the three predictors with the higher relative influence. The best GAMLSS model retained mix-layer depth, mix-layer temperature, total layer temperature, total runoff and 10-m wind speed as significant predictors (p<0.001). Regarding the phytoplankton biomass both modelling approaches had less explanatory power than those for chlorophyll-a. Concerning the predictive performance of the models both the BRT and GAMLSS models for chlorophyll-a outperformed those for phytoplankton biomass. Overall, we consider these findings promising for future limnological studies as they bring forth new perspectives in modelling ecosystem responses to a wide range of climate and lake variables. As a concluding remark, climate reanalysis can be an extremely useful asset for lake research and management.
... Agricultural activity in particular is considered a major driver of hydromorphological modifications in Mediterranean rivers [15][16][17]. For instance, bank and channel resectioning is used as a practice of flood defense management to protect neighboring agricultural land from flood events. ...
The riparian zone plays an important role in the ecological stability of rivers. In particular the quality of the riparian vegetation is a significant component of the hydromorphological status. In Europe, the QBR index (Qualitat del Bosc de Ribera) and the River Habitat Survey (RHS) are commonly used for the qualitative assessment of the riparian vegetation taking into account the riparian vegetation cover, the cover structure and the channel alterations. In this study, we estimated the QBR index and the Riparian Quality index, which is derived from the RHS method, for 131 river reaches of the National Monitoring Network of Greece. These reaches were surveyed during the summer periods of 2018, 2019 and 2020, through the implementation of the National Monitoring Program in compliance with the Water Framework Directive (WFD). The aim of this study is to assess the riparian vegetation status by comparing these two indices and to identify linkages with the dominant land uses within the catchment. The Riparian Quality Index and the Habitat Modification Score, also estimated from the RHS method, were positively correlated showing that the overall hydromorphological alteration is associated with the degradation of the riparian vegetation. In addition, the QBR index and the Riparian Quality Index correlated negatively with the agricultural land uses in the catchment area and positively with the natural ones (e.g. forests). Both indices seem to present similar quality assessments. These results constitute a first assessment of the status of the riparian zones in Greek rivers in accordance with the WFD and set the basis for further research for the development of new and effective tools for a rapid quality assessment of the riparian zones.
... The SWAT model developed by the Agricultural Research Service of the United States Department of Agriculture (USDA-ARS) is a continuous-time, semi-distributed, and physics-based water quality model (Arnold et al., 1998;Gassman et al., 2014;Romagnoli et al., 2017) for simulating hydrological cycle, plant growth cycle and transportation of sediments (Arnold 125 et al., 1998;Pyo et al., 2019;Stefanidis et al., 2018;Wu et al., 2011). The SWAT model delineates a catchment into subbasins based on the stream network and topography and subsequently into Hydrological Response Units (HRUs) representing different combinations of soil types, land use, and slope. ...
Reliable drought monitoring and mastering the laws of drought propagation are the basis for regional drought prevention and resistance. Multivariate drought indicators considering meteorological, agricultural, and hydrological information may fully describe drought information; however, too short or missing hydrological variables in cold and arid regions make it difficult to monitor drought. This paper proposes a method combining SWAT and empirical Kendal distribution function (KC') for drought monitoring. The SWAT model, based on the principle of runoff formation, was used to simulate the hydrological variables of the drought evolution process. Three univariate drought indexes, namely meteorological drought (SPEI), agricultural drought (SSI), and hydrological drought (SDI) were constructed using parametric and non-parametric methods to analyze the propagation time of meteorological drought to agricultural drought and hydrological drought. The KC' was used to build a multivariable comprehensive Meteorology–Agriculture–Hydrology Drought Index (MAHDI) that takes into account meteorological, agricultural and hydrological drought to analyze the characteristics of a comprehensive drought evolution. The Jinta River in the inland basin of northwest China was used as the study area. The results show that agricultural and hydrological drought have a seasonal lag time for meteorological drought. The degree of drought in the river basin is high in the northern and low in the southern regions. The MAHDI captured drought conditions characterized by a univariate drought index; however, the ability to characterize mild and moderate droughts is stronger than severe droughts. The index also captured the occurrence and end of drought time; therefore, it is an acceptable comprehensive drought index. In addition, the comprehensive drought conditions showed insignificant drought trends in spring and summer, and showed insignificant warm and humidification trends in autumn, winter and annual scale. The results provided theoretical support for the drought control in the Jinta River Basin. This method may be applied for drought monitoring in other watersheds with a shortage of measured data.
... In addition, this integrated modelling approach is still at an early stage of development. Some studies considered biological responses at broader community level and used univariate community metrics like EPT taxa (Li et al., 2018;Nukazawa et al., 2018;Stefanidis et al., 2018), others have explored impacts of single drivers either land use change or climate change affecting the stream biota (e.g (Krynak and Yates, 2018;Mustonen et al., 2018;Woznicki et al., 2016). Overall, the above mentioned studies have in common that they do not allow to assess species-specific responses of site-specific macroinvertebrate species to altered flow projections affected by multiple drivers. ...
... Moreover, the literature reports several examples of machine learning ecological models addressing the effects of climate and socio-economic scenarios on biological communities (e.g. Hain et al., 2018;Herrero et al., 2018;Stefanidis et al., 2018). ...
Anthropogenic activities are seriously endangering the conservation of biodiversity worldwide, calling for urgent actions to mitigate their impact on ecosystems. We applied machine learning techniques to predict the response of freshwater ecosystems to multiple anthropogenic pressures, with the goal of informing the definition of water policy targets and management measures to recover and protect aquatic biodiversity. Random Forest and Gradient Boosted Regression Trees algorithms were used for the modelling of the biological indices of macroinvertebrates and diatoms in the Tagus river basin (Spain). Among the anthropogenic stressors considered as explanatory variables, the categories of land cover in the upstream catchment area and the nutrient concentrations showed the highest impact on biological communities. The model was then used to predict the biological response to different nutrient concentrations in river water, with the goal of exploring the effect of different regulatory thresholds on the ecosystem status. Specifically, we considered the maximum nutrient concentrations set by the Spanish legislation, as well as by the legislation of other European Union Member States. According to our model, the current nutrient thresholds in Spain ensure values of biological indices consistent with the good ecological status in only about 60% of the total number of water bodies. By applying more restrictive nutrient concentrations, the number of water bodies with biological indices in good status could increase by almost 40%. Moreover, coupling more restrictive nutrient thresholds with measures that improve the riparian habitat yields up to 85% of water bodies with biological indices in good status, thus proving to be a key approach to restore the status of the ecosystem.
... This is due to the different land uses upstream: while the Monte Novo watershed has a larger occupation with more intensive croplands (annual cultures), resulting in higher use of fertilizers and soil mobilization, in the Vigia watershed there are larger agroforestry and forest areas with a lower phosphorus export potential. These results are in line with the influence of future climate scenarios on phosphorus exports stressed by El-Khoury et al. (2015), Cerkasova et al. (2018) and Stefanidis et al. (2018). ...
Future climate for the Mediterranean climatic region is expected to bring an increase in temperatures, decrease in the precipitation quantity and shifts in the seasonal precipitation pattern. Although the impacts of climate change on water resources have been relatively well explored for the Mediterranean climatic region, the specific consequences for reservoirs and, in particular, water availability and irrigation issues have been less studied. The objective of this work is two-fold: (i) to assess the impacts of future climate changes on water resources availability, quality (focusing on phosphorus loads as this is the limiting nutrient for eutrophication) and irrigation needs for two multipurpose reservoirs in southern Portugal; (ii) to suggest climate change adaptation strategies, especially for the agricultural sector. To this end, the SWAT model was first calibrated against existing data on reservoir inflows as well as phosphorus loads. Then, SWAT was run with climate derived EURO-CORDEX models (RCA4/RACMO22E) for four periods (1970–2000, 2010–2040, 2040–2070 and 2070–2100). Water availability was analysed using the Water Exploitation Index (WEI) that was calculated for both reservoirs combining changes of inflows and irrigation requirements. The results indicated that climate change will negatively impact water availability in both reservoirs, especially under RCP8.5. In the case of the Monte Novo reservoir, future domestic water supply could be constrained by water quality problems related with phosphorus loads. For Vigia reservoir, the high water exploitation will lead to water scarcity problems, mainly as this reservoir on present-day conditions is restrictive on irrigation requirements. Adaptation strategies such as the implementation of high end technology (e.g. soil moisture and plant water stress probes, satellite imagery and drones to evaluate water stress – NDVI) as well as the renewal of the irrigation network and adequate crop selection can help attenuating the effects of climate change on the water resources in this region.
... The SWAT model, developed by the Agricultural Research Service of the United States Department of Agriculture (USDA-ARS), is a distributed and physically-based watershed hydrological model (Arnold et al., 1998;Gassman et al., 2014;Romagnoli et al., 2017;Wu et al., 2018) for exploring the hydrological cycle, plant growth, transportation of sediment, and agricultural chemical yields on a daily time step (Arnold et al., 1998;Panagopoulos et al., 2012;Pyo et al., 2017;Stefanidis et al., 2018;Wu et al., 2012;Zhao et al., 2019). The main outputs of SWAT are surface runoff, lateral flow, baseflow, ET, soil water content (SW), water yield (WLD), sediment load, and nutrient loads. ...
Understanding the spatiotemporal evolution of drought is vital for effective water resources management especially in arid and semi-arid regions and under climate change. In this study, we developed the Soil and Water Assessment Tool (SWAT)-based drought evaluation tool and used it to investigate the spatiotemporal change of drought and its driving factors over the past 50 years (1965–2014) in a typical semi-arid area, the Wei River Basin, in the Loess Plateau. The temporal trend analysis of precipitation showed an intensified hydrological cycle with a longer dry interval, and the substantially decreased wind speed resulted in a significant decrease in the evapotranspiration and a slight increase in the soil water content. The spatiotemporal analysis of drought identified the vulnerable areas and indicated that spring drought was exacerbating. Overall, this study can be informative and valuable for the drought assessment and disaster alleviation in the Loess Plateau area.
... Particularly for Greece, there is a significant amount of research that has underpinned the impacts of agriculture in the water chemistry of running waters [21,23], as many anthropogenic pressures are linked with the agricultural activity. Catchment model simulations have demonstrated that the use of fertilizers in heavily agricultural catchments results in increased concentrations of nitrates and phosphates under various scenarios of future climate and management [36]. In addition to agricultural driven diffuse pollution, industrial point sources of organic pollution in the form of small agro-industries (e.g. ...
European rivers are under ecological threat by a variety of stressors. Nutrient pollution, soil erosion, and alteration in hydrology are considered the most common problems that riverine ecosystems are facing today. Not surprisingly, river monitoring activities in Europe have been intensified during the last few years to fulfil the Water Framework Directive (WFD) requirements. With this article, we present a nationwide assessment of the water quality and hydromorphological variability in Greek Rivers based on the results of the national monitoring program under the WFD. Water quality and hydromorphological data from 352 sites belonging to 221 rivers were explored with principal component analysis (PCA) to identify main environmental gradients and the variables that contribute the most to the total variance. Nitrate, phosphate, ammonium and electrical conductivity were identified as the most important water chemistry parameters, and typical vector-based spatial data analysis was applied to map their spatial distribution at sub-basin scale. In addition, we conducted simple linear models between the aforementioned parameters and the share of land uses within the basin of each sampling site in order to identify significant relationships. Agriculture was the most important land use affecting the nitrate and electrical conductivity, while artificial surfaces were the best predictor for phosphate and ammonium. Concerning the hydromorphological variability, fine types of substrate and discharge were the variables with the highest contribution to the total variance. Overall, the results of this article can be used for the preliminary assessment of susceptible areas/rivers to high levels of nutrient pollution that can aid water managers to formulate recommendations for improvement of further monitoring activities. Furthermore, our findings implicate the need for enhancement of agri-environmental measures and reduction of point-source pollution in disturbed areas to avert the risk of further environmental degradation under the anticipated global change.
... In addition, the increased CO 2 concentration will directly affect crop growth and development (Sreeharsha et al., 2015;Xu et al., 2016), which will further alter food production and agricultural land use (Olesen and Bindi, 2002). The impacts of increasing CO 2 concentration and global warming on extreme climate events, hydrology, and crop production are worldwide concerns (Panagopoulos et al., 2014(Panagopoulos et al., , 2015Stefanidis et al., 2018;Ye and Grimm, 2013;Williams et al., 2015). For example, Bourdages and Huard (2010) reported a general increase in temperatures, reduction in the duration of snow period, and increase in most rainfall indicators and extremes under future climate conditions at 12 stations in Ontario, Canada. ...
Modeling the effects of climate change on hydrology and crop yield provides opportunities for choosing appropriate crops for adapting to climate change. In this study, climate change impacts on irrigated corn and sorghum, dryland (rainfed) sorghum, and continuous fallow in the Northern High Plains of Texas were evaluated using an improved Soil and Water Assessment Tool (SWAT) model equipped with management allowed depletion (MAD) irrigation scheduling. Projected climate data (2020-2099) from the Coupled Model Intercomparison Project Phase 5 (CMIP 5) of 19 General Circulation Models (GCMs) were used. Climate data were divided into four 20-year periods of near future (2020-2039), middle (2040-2059), late (2060-2079), and end (2080-2099) of the 21st century under two Representative Concentration Pathway (RCP) emission scenarios (RCP 4.5 and RCP 8.5). For irrigated corn, median annual crop evapotranspiration (ET) and irrigation decreased by 8%-25% and 15%-42%, respectively, under the climate change scenarios compared to the historical period (2001-2010). The median yield was reduced by 3%-22% with exponentially decreases in the latter half of the 21st century. For sorghum, the reduction of median annual crop ET ranged from 6%-27%. However, the decline in the median annual irrigation was within 15%, except for the 2060-2079 and 2080-2099 periods under RCP 8.5 scenarios with 30% and 49% reductions in median annual irrigation. The median irrigated sorghum yield declined by 6%-42%. The median annual crop ET of dryland sorghum decreased by 10%-16%. The reduction in median yield was within 10% of the historical dryland sorghum yield. The decrease in median annual evaporation varied from 15%-23% under future continuous fallow conditions. The elevated CO2 level of future climate scenarios was the primary factor for the decrease in the ET and irrigation. The reduction in future crop yield was mainly attributed to the shortening of the maturity period caused by increased future temperature.
... The RCPs refer to radiative forcing pathways that describe an emission trajectory and concentration by the year 2100, while the SSPs are defined as 'reference pathways' describing plausible alternative trends in the evolution of society and ecosystems. Such scenarios have been already produced and used in local analyses in the EU funded MARS project [52,53], and would be interesting to run and give rise to hydrologic alteration estimates at the European scale in the future. ...
The hydrologic regime of a river is one of the factors determining its ecological status. This paper tries to indicate the present hydrologic stress occurring across European rivers on the basis of model integration. This results in a pan-European assessment at the resolution of the functional elementary catchment (FEC), based on simulated daily time-series of river flows from the model PCR-GLOBWB. To estimate proxies of the present hydrologic stress, two datasets of river flow were simulated under the same climate, one from a hypothetic least disturbed condition scenario and the second from the anthropogenic scenario with the actual water management occurring. Indicators describing the rivers’ hydrologic regime were calculated with the indicators of hydrologic alteration (IHA) software package and the river total mean flow and the relative baseflow magnitude over the total flow were used to express the deviations between the two scenarios as proxy metrics of rivers’ hydrologic alteration or hydrologic stress. The alteration results on Europe’s FEC-level background showed that Southern Europe is more hydrologically stressed than the rest of Europe, with greater potential for hydrology to be clearly associated with river segments of unreached good ecological status and high basin management needs.
... 75 The influence of climate change and anthropogenic activities on ES has been documented in previous studies (e.g. Milly et al. 2002, Huntington 2006, Delphin et al. 2016, Gao et al. 2016, Sinha et al. 2018, Stefanidis et al. 2018. Climate change has had an impact on the 80 water cycle across the globe, resulting in a higher frequency of extreme precipitation, as well as the occurrence of severe droughts (Easterling et al. 2000). ...
Assessment of the impact of changes in climate and land use and land cover (LULC) on ecosystem services (ES) is important for planning regional-scale strategies for sustainability and restoration of ES. The Upper Narmada River Basin (UNRB) in peninsular India has undergone rapid LULC change due to recent agricultural expansion. The impact of future climate and LULC change on ES in the UNRB is quantified and mapped using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST 3.3.0) tool. Our results show that water yield is projected to increase under climate change (about 43% for representative concentration pathway 4.5 for 2031–2040), whereas it is projected to decrease under the LULC change scenario. Sediment export is projected to increase (by 54.53%) under LULC change for 2031–2040. Under the combined effect of climate and LULC change, both water yield and sediment export are expected to increase. Climate change has a greater impact on projected water yield than LULC change, whereas LULC has greater impact on sediment export. Spatial analysis suggests a similar trend of variation in relative difference (RD) of ES in adjacent sub-basins. The quantified changes in ES provisioning will benefit future land management, particularly for operation of the Rani Avanti Bai Sagar Reservoir downstream of the UNRB.
... (1) the analysis of the response relationship between socioeconomic system factors and river system factors (such as the impact of land use on river ecology) via simple statistics (Van De Wiel et al., 2011;Bussi et al., 2016;Huang et al., 2017;Parker et al., 2018;Stefanidis et al., 2018); (2) the changes of river system indexes before and after the construction of a project (such as the influence of sluice or dam construction on river water quality or aquatic ecology) via river system evaluation (Torabi Haghighi et al., 2014;Fearnside, 2016;Santos et al., 2017;Remo et al., 2018); and (3) the comparison between river system indexes changes and different levels of human activity (Whitfield, 1983;Coelho et al., 2012). There are only few studies about the influence of socioeconomic system on river system based on inherent relationships and correlations between socioeconomic system and river system indicators. ...
The quantitative assessment of the impact of socioeconomic development on river water environment is important to the scientific management of river basins. However, current methods have high data requirements or are difficult to deal with the impact between systems (which is defined by a collection of indicators). This paper first uses canonical correlation analysis (CCA) to understand the relationship between socialeconomic system (defined by a set of indicators reflecting socioeconomic development) and river system (defined by a set of indicators reflecting river water environment), and then proposes a method to assess the impact of socioeconomic system on river system by integrating CCA and the degrees of influence of river system indicators. The proposed method and framework are applied to the Shaying River Basin with the characteristics of multi-sluices, high pollution, and dense population based on data from 2000 to 2015. Results indicate that socioeconomic and river systems are highly related to each other with the average influence degree of greater than 0.9, indicating very close relationships between socioeconomic and river systems. The changes of influence degree vary between 0.19 and 0.79 with a turning point in 2010. Most of the influence levels are “moderate” (influence degree between 0.4 and 0.6) or “high” (influence degrees between 0.6 and 0.8) before 2010 but become to “low” (influence degrees between 0.2 and 0.4) since then. In addition, the influence degree shows a significant increase from upstream to downstream with Zhoukou Station as the turning point, meaning that the stronger the human activity is, the greater the impact of the socioeconomic system on the river system is. The main influential factors are population density and sewage treatment rate. The proposed method contributes to the research in river management with limited data availability and the results can serve as an important reference for basin management.
The chapter covers the current status of salmonid fishes in the Western Balkans in the Adriatic, Aegean, and Danube drainage basins on the territories of Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, Serbia, and North Macedonia. Salmonids (family Salmonidae) are freshwater and anadromous fish native to the northern hemisphere. The family is composed of three subfamilies: Salmoninae, Thymallinae, and Coregoninae. Only species of the families Salmoninae and Thymallinae occur naturally in the inland waters of the Western Balkans; these species do not normally migrate to the sea in this area. Of the Salmoninae, in addition to the Danube salmon (Hucho hucho), a large number of trout species (Salmo spp.) can be found here, which is hard to find anywhere else in their distribution range. Two species of the Thymallinae are represented, the European grayling (Thymallus thymallus), which has its southernmost distribution limit in this region, and the Adriatic grayling (Thymallus aeliani) from the northern Adriatic basin. In addition, exotic salmonid species—e.g. rainbow trout (Oncorhynchus mykiss), brook char (Salvelinus fontinalis), and lake char (Salvelinus umbla)—have been introduced and naturalized in a number of water bodies.
In the inland waters of the Western Balkans, salmonids play an important economic and social role in both commercial and recreational fisheries. Unfortunately, this has long since led to the fact that many of the stocks have been severely depleted, in some cases almost destroyed, by the pressure of fishing. To counteract this, stocking with hatchery fish is common in many places. However, stocking with non-native brown trout has often resulted in genetic introgression into the autochthonous populations of Salmo trouts and loss of their genetic integrity. Other threats to the survival of salmonid populations include water pollution from agriculture and sewage, as well as dam construction, which has particularly increased recently. The increased demand for drinking water as a result of the growing tourism industry poses an additional threat to aquatic ecosystems and could be exacerbated by climate change.
Foresight science is a systematic approach to generate future predictions for planning and management by drawing upon analytical and predictive tools to understand the past and present, while providing insights about the future. To illustrate the application of foresight science in conservation, we present three case studies: identification of emerging risks to conservation, conservation of at-risk species, and aid in the development of management strategies for multiple stressors. We highlight barriers to mainstreaming foresight science in conservation including knowledge accessibility/organization, communication across diverse stakeholders/decision makers, and organizational capacity. Finally, we investigate opportunities for mainstreaming foresight science including continued advocacy to showcase its application, incorporating emerging technologies (i.e., artificial intelligence) to increase capacity/decrease costs, and increasing education/training in foresight science via specialized courses and curricula for trainees and practicing professionals. We argue that failure to mainstream foresight science will hinder the ability to achieve future conservation objectives in the Anthropocene.
How the added value of dynamically downscaled climate variables can be transferable to the hydrological impact assessment has been a long standing issue. This study investigates the potential benefit of highresolution climate data locally tailored over South Korea in terms of the reduction of uncertainties in hydrological projections. For this purpose, a large ensemble consisting of three Global Climate Model (GCM) projections and their downscaling products with different resolutions (i.e., 20 and 5 km), and four bias correction (BC) methods is fed into a semi-distributed hydrological model (HM) customized over Korean river basins. The in-depth comparison among the 45-members hydrological simulations proves that the added value of RCM would not be erased by the application of BC. While this study acknowledges the necessity of BC to remove the systematic bias in climate simulations, it is found that the high-resolution dynamical downscaling can significantly narrow the spread brought with different BC methods, thus reducing the uncertainty in the projected hydrological change. The projected streamflow changes for both the mean of wet season and the high flows indicate that there will be an intensified runoff, especially for the extremes, over South Korea under the warming. Altogether, this study provides a valuable exploration of uncertainty reduction in hydrological projections from the perspective of resolution effect of dynamical downscaling, which is meaningful for hydroclimate studies and climate change impact assessment.
The paper presents materials on a comprehensive assessment of reservoirs for commercial aquaculture, exemplified by some waterbodies in the Rostov region. We have examined 24 waterbodies located in the southern and south-eastern Rostov region. The assessment of reservoirs was carried out based on hydrological and hydrochemical indicators, the point score of which was carried out in four sets of issues. Almost all the studied water bodies because of the lack of required water supply have been classified as reservoirs with risky fish farming. Most aquaculture reservoirs recommended for commercial farming are found in the zone of a very arid climate, characterized by annual precipitation ratio of 0.33-0.44. A brief hydrochemical description of each investigated waterbody can be used to form scientifically-based recommendations for the organization of commercial fish farms in Russia.
Climate change is a worldwide reality with significant effects on hydrological processes. It has already produce alterations in streamflow regime and is expected to continue in the future. To counteract the climate change impact, a better understanding of its effects is necessary. Hydrological models in combination with Indicators of Hydrologic Alteration (IHA) suppose an up-to-date approach to analyze in detail the impacts of climate change on rivers. In this study, the Soil and Water Assessment Tool (SWAT) model and Indicators of Hydrologic Alteration in Rivers (IAHRIS) software were successfully applied in Aracthos River basin, an agricultural watershed located in the north-western area of Greece. Statistical indices showed an acceptable performance of the SWAT model in both calibration (R² = 0.74, NSE = 0.54, PBIAS = 17.06%) and validation (R² = 0.64, NSE = 0.36, PBIAS = 12.31%) periods on a daily basis. To assess the future hydrologic alteration due to climate change in Aracthos River basin, five Global Climate Models (GFDL-ESM2, HadGEM2-ES, IPSL-CM5A-LR, MIROC-ESM-CHEM and NorESM1-M) were selected and analyzed under two different emission scenarios (RCP 4.5 and RCP 8.5) for a long-term period (2070–2099). Results indicate that precipitation and flow is expected to be reduced and maximum and minimum temperature to be increased, compared to the historical period (1970–1999). IHA, obtained from IAHRIS software, revealed that flow regime can undergo a severe alteration, mainly on droughts that are expected to be more significant and longer. All these future hydrologic alterations could have negative consequences on the Aracthos River and its surroundings. The increase of droughts duration in combination with the reduction of flows and the alteration of seasonality can affect the resilience of riverine species and it can produce the loss of hydraulic and environmental diversity. Therefore, this study provides a useful tool for decision makers to develop strategies against the impact of climate change.
Understanding the effects of environmental change on natural ecosystems is a major challenge, particularly when multiple stressors interact to produce unexpected “ecological surprises” in the form of complex, nonadditive effects that can amplify or reduce their individual effects. Animals often respond behaviorally to environmental change, and multiple stressors can have both population-level and community-level effects. However, the individual, not combined, effects of stressors on animal behavior are commonly studied. There is a need to understand how animals respond to the more complex combinations of stressors that occur in nature, which requires a systematic and rigorous approach to quantify the various potential behavioral responses to the independent and interactive effects of stressors. We illustrate a robust, systematic approach for understanding behavioral responses to multiple stressors based on integrating schemes used to quantitatively classify interactions in multiple-stressor research and to qualitatively view interactions between multiple stimuli in behavioral experiments. We introduce and unify the two frameworks, highlighting their conceptual and methodological similarities, and use four case studies to demonstrate how this unification could improve our interpretation of interactions in behavioral experiments and guide efforts to manage the effects of multiple stressors. Our unified approach: (1) provides behavioral ecologists with a more rigorous and systematic way to quantify how animals respond to interactions between multiple stimuli, an important theoretical advance, (2) helps us better understand how animals behave when they encounter multiple, potentially interacting stressors, and (3) contributes more generally to the understanding of “ecological surprises” in multiple stressors research.
The Pinios river basin is a major agricultural area in Greece, which faces environmental issues with water scarcity and nutrient pollution. Recent Earth Observation satellite data and ground truth information were combined to produce an updated land use map, focusing on irrigated crop areas. A process-based hydrological model (SWAT) was set up using the produced land use map. The model was calibrated and validated using observed streamflows and nutrient concentrations at selected gauging stations. Four irrigation and nutrient management practices related to resource efficiency (i.e. deficit irrigation, reduced fertilization, combination of deficit irrigation and fertilization, precision agriculture) were modelled and simulated. The sustainability of the management practices was assessed using indicators to quantify their impacts on the water-energy-land-food nexus of the river basin.
Water availability on the continents is important for human health, economic activity, ecosystem function and geophysical processes. Because the saturation vapour pressure of water in air is highly sensitive to temperature, perturbations in the global water cycle are expected to accompany climate warming. Regional patterns of warming-induced changes in surface hydroclimate are complex and less certain than those in temperature, however, with both regional increases and decreases expected in precipitation and runoff. Here we show that an ensemble of 12 climate models exhibits qualitative and statistically significant skill in simulating observed regional patterns of twentieth-century multidecadal changes in streamflow. These models project 10-40% increases in runoff in eastern equatorial Africa, the La Plata basin and high-latitude North America and Eurasia, and 10-30% decreases in runoff in southern Africa, southern Europe, the Middle East and mid-latitude western North America by the year 2050. Such changes in sustainable water availability would have considerable regional-scale consequences for economies as well as ecosystems.
The fate of seasonal river ecosystem habitats under climate change
essentially depends on the changes in annual recharge of the river, which are
related to alterations in precipitation and evaporation over the river basin.
Therefore, the change in climate conditions is expected to significantly
affect hydrological and ecological components, particularly in fragmented
ecosystems. This study aims to assess the impacts of climate change on the
streamflow in the Dinder River basin (DRB) and to infer its relative possible
effects on the Dinder National Park (DNP) ecosystem habitats in Sudan. Four
global circulation models (GCMs) from Coupled Model Intercomparison Project
Phase 5 and two statistical downscaling approaches combined with a
hydrological model (SWAT – the Soil and Water Assessment Tool) were used to
project the climate change conditions over the study periods 2020s, 2050s,
and 2080s. The results indicated that the climate over the DRB will become
warmer and wetter under most scenarios. The projected precipitation
variability mainly depends on the selected GCM and downscaling approach.
Moreover, the projected streamflow is quite sensitive to rainfall and
temperature variation, and will likely increase in this century. In contrast
to drought periods during the 1960s, 1970s, and 1980s, the predicted climate
change is likely to affect ecosystems in DNP positively and promote the
ecological restoration for the habitats of flora and fauna.
Global environmental change entails not only climatic alterations, but also changes in land use. Freshwater ecosystems are particularly sensitive to both of these changes, and their sustainable management requires better information on likely responses.
To examine the effects of climate and land use on the freshwater community, the distributions of stream macroinvertebrates of the Changjiang catchment in south‐east China were modelled. The present distributions of 72 taxa were predicted using environmental variables generated by regional climate, land‐use and hydrological models.
Hydrological predictors, sensitive to both climate and land use, were the most relevant predictors in the species distribution models ( SDM s), followed by land use.
The stream macroinvertebrates’ distributions were then projected for the period 2021 to 2050 using three different future scenarios: (i) climate change, (ii) land‐use change and (iii) climate and land‐use change combined.
Land‐use change was predicted to have the strongest negative impact on the community, with reductions in local richness (−20%), predicted diversity (−0.3%) and range size (−25%) and a general shift towards higher altitudes (+12%). The climate‐change scenario had a negative effect on predicted diversity (−0.1%) and resulted in a moderate altitudinal shift (+3%) along with increased richness (+15%) and range size (+19%). In the combined scenario, climate and land‐use changes counterbalanced each other to a certain degree, but had an overall detrimental effect.
The results underscore the high relevance of land‐use change in future distribution predictions, exemplify the possible effect of interactions between land use and climate on hydrology and indicate how such responses can vary among freshwater taxa. The model also allows the detection of key environmental variables, the identification of vulnerable species and the definition of their potential distributions. This information is essential to establishing effective management and conservation strategies and gives a more comprehensive insight into the possible effects of global environmental change on freshwater ecosystems.
This study presents the development of a multimetric index using benthic macroinvertebrates (BMI) to assess the ecological health of highland rivers in Ethiopia. BMI were collected from 22 reference and 82 impaired sites determined based on hydro-morphological, land use, physical and chemical criteria. Of 75 potential metrics tested to integrate the multimetric index, only nine core metrics were selected based on their abilities to istinguish reference and impaired sites, strength of correlation with pertinent environmental parameters and their independence from other metrics. The metrics retained in the multimetric index were total number of taxa, EPT-BH>1sp (Ephemeroptera, Plecoptera and Trichoptera taxa where Baetidae and Hydropsychidae taxa are considered if they consist more than one taxon), % Oligochaeta and Red Chironomidae, % COPTE Coleoptera, donata, Plecoptera, Trichoptera and Ephemeroptera), % EPT-BCH (EPT without Baetidae, Caenidae and Hydropsychidae), ASPT-SASS (Average South African Scoring System Per Taxa), FBI (Family Biotic Index), % hredders and % collector gathering. The final index derived from these metrics was divided in to five river quality class (high, good, moderate, poor and bad). A validation procedure showed that the index is stable along different hydrological conditions and sensitive to the current range of anthropogenic disturbances in Ethiopian highland rivers.
Possible changes in the intensity of heavy
precipitation events at the end of the twenty-first century
over the Euro-Mediterranean region are investigated, using
a subset of numerical climate simulations taking part to the
fifth phase of the Coupled Model Intercomparison Project
(CMIP5). As a measure of the intensity associated with
heavy precipitation events, we use the difference between
the 99th and the 90th percentiles. Despite a slight tendency
to underestimate the observed heavy precipitation intensity
during summer and to overestimate it during winter, the
considered CMIP5 models well represent the observed
patterns of the defined 99th–90th percentile metric during
both seasons for the 1997–2005 period over the Euro-
Mediterranean region. Over the investigated domain, an
increase of the width of the right tail of the precipitation
distribution is projected in a warmer climate, even over
regions where nearly the entire precipitation distribution
becomes dryer. This is the case of the European domain
within the 45N–55N belt.
Human activities within fluvial corridors and surrounding landscapes have persistently stressed riparian ecosystems, particularly in Iberian Mediter-ranean-type streams. The impact of human disturbance relative to natural environmental factors in shaping riparian vegetation is still poorly understood. Both regional variables (such as altitude and precipitation), and site-specific characteristics (such as substrate and riverbank modifications) were analysed as potential determinants of riparian vegetation patterning to determine the relative influences of the diverse land-use types and environmental factors on the composition (including floristic species richness and percentage cover of trees, shrubs and woody climbers) and integrity (width of riparian woods and patterns of longitudinal continuity) of riparian woods in eight river basins of the Tagus fluvial system (Portugal). There was patchy establishment of riparian woods, with generally low average width and low species richness, as well as significant inter-basin differences and upstream-downstream variations in riparian features. Species distribution was clearly determined by environmental factors, such as human disturbance on the riverbanks and geological background , and the environmental variables and the land use in the river valley partially explained the integrity of riparian woody vegetation. The results highlight the predictive capability of reach-level features; it appears that, linked with the geomorphological and climate context, small-scale human disturbances on riparian corridors play a major role in explaining the remaining biological variability.
The effort to manage irrigation water use through the adoption and implementation of agricultural best management practices (BMPs) is crucial for meeting water bodies' sustainability in water-deficient agricultural areas. This paper presents the development of an efficient decision support tool able to suggest the optimal location for placing high-and low-tech irrigation BMPs, such as deficit irrigation, conveyance efficiency improvement, precision irrigation, and wastewater reuse, and demonstrates its application in the water-scarce Pinios river basin in central Greece. The tool uses the SWAT (soil and water assessment tool) model as the BMP and hydrologic simulator and a multiobjective genetic algorithm, which, based on calculated cost data, optimizes the cost-effectiveness of management schemes across the landscape. From the analysis of the results produced and the optimal river basin BMP configurations under the current and a volumetric water pricing scenario and under a +/- 25% variation of the cost parameters, the study concludes that a number of different BMPs at an affordable implementation cost, along with a tiered water pricing system that could address socioeconomic heterogeneities, would form a sustainable action plan against desertification in the highly water-deficient Pinios basin. The methodology and tool are considered to be easily applicable in other river basins and could be used to assist in more cost-effective implementation of environmental legislation. (C) 2014 American Society of Civil Engineers.
The new scenario framework for climate change research envisions combining pathways of future radiative forcing and their associated climate changes with alternative pathways of socioeconomic development in order to carry out research on climate change impacts, adaptation, and mitigation. Here we propose a conceptual framework for how to define and develop a set of Shared Socioeconomic Pathways (SSPs) for use within the scenario framework. We define SSPs as reference pathways describing plausible alternative trends in the evolution of society and ecosystems over a century timescale, in the absence of climate change or climate policies. We introduce the concept of a space of challenges to adaptation and to mitigation that should be spanned by the SSPs, and discuss how particular trends in social, economic, and environmental development could be combined to produce such outcomes. A comparison to the narratives from the scenarios developed in the Special Report on Emissions Scenarios (SRES) illustrates how a starting point for developing SSPs can be defined. We suggest initial development of a set of basic SSPs that could then be extended to meet more specific purposes, and envision a process of application of basic and extended SSPs that would be iterative and potentially lead to modification of the original SSPs themselves.
Reduction of flow constitutes one of the most severe human alterations to rivers, as it affects the key abiotic feature of these ecosystems. While there has been considerable progress in understanding the effects of reduced flow on benthic macroinvertebrates, cascading effects of flow reduction on dissolved oxygen concentrations (DO) have not yet received much attention. We compared the macroinvertebrate composition between reference conditions and a situation after several years of discharge reduction in the Spree River (Brandenburg, Germany). Community composition shifted from rheophilic species to species indifferent to flow conditions. Filter feeders were partially replaced by collector/gatherers, which likely reduces the retention of organic matter, and thus the self-purification capacity of the river section. These shifts were associated with low discharge during summer, cascading into daily DO concentration minima of less than 5 mg l−1 which prevailed 74% of the days in summer. This depletion of DO after flow reduction presumably caused the observed species turnover. Hence, flow reduction in lowland rivers may not only directly impair the ecological functions provided by benthic macroinvertebrates but may also act indirectly by depleting DO concentrations.
The majority of studies comparing the response of biotic metrics to environmental stress in rivers are based on relatively small, homogeneous datasets resulting from research projects. Here, we used a large dataset from Austrian and German national river monitoring programmes (2,302 sites) to analyse the response of fish, diatom and macroinvertebrate metrics to four stressors acting at different scales (hydromorphology, physico-chemistry, riparian and catchment land use). Nutrient enrichment and catchment land use were the main discriminating stressors for all organism groups, over-ruling the effects of hydromorphological stress on the site scale. The response of fish metrics to stress was generally low, while macroinvertebrate metrics performed best. The Trophic Diatom Index (TDI) responded most strongly to all stressors in the mountain streams, while different metrics were responsive in the lowlands. Our results suggest that many rivers are still considerably affected by nutrient enrichment (eutrophication), which might directly point at implications of catchment land use. We conclude that monitoring datasets are well-suited to detect major broad-scale trends of degradation and their impact on riverine assemblages, while the more subtle effects of local-scale stressors require stream type-specific approaches.
Streams and rivers in mediterranean-climate regions (med-rivers) are subjected to sequential, yet contrasting hydrologic disturbances of drying and flooding. Although seasonally predictable, these disturbances can vary in intensity and duration within and among mediterranean-climate regions (med-regions). Consequently, med-rivers differ in the permanence of their aquatic habitats. To persist, species have acquired matched resistance and resilience adaptations. They gain resistance either by enduring the stress or avoiding it. Community recovery (or resilience) is achieved with cessation of hydrologic stress that permits maximization of re-colonization and reproduction. Endurance strategies are usually disturbance-specific, but avoidance enables organisms to cope with both drying and flooding, and is the prevalent resistance strategy. Correspondingly, community persistence depends to a large extent on the integrity of refuges, an aspect that has so far been little explored. Existing information suggests that seasonal community succession becomes more pronounced with increasing aridity and declining water permanence. The invertebrate community in semi-arid med-rivers can therefore undergo succession through three to four identifiable assemblages, whereas in perennial streams the difference between wet and dry period assemblages is smaller. Community turnover is influenced by the intensity of the hydrologic disturbances and varies between wet and drought years.
Climate change is predicted to have profound effects on freshwater organisms due to rising temperatures and altered precipitation regimes. Using an ensemble of bioclimatic envelope models (BEMs), we modelled the climatic suitability of 191 stream macroinvertebrate species from 12 orders across Europe under two climate change scenarios for 2080 on a spatial resolution of 5 arc minutes. Analyses included assessments of relative changes in species' climatically suitable areas as well as their potential shifts in latitude and longitude with respect to species' thermal preferences. Climate-change effects were also analysed regarding species' ecological and biological groupings, namely (1) endemicity and (2) rarity within European ecoregions, (3) life cycle, (4) stream zonation preference and (5) current preference. The BEMs projected that suitable climate conditions would persist in Europe in the year 2080 for nearly 99% of the modelled species regardless of the climate scenario. Nevertheless, a decrease in the amount of climatically suitable areas was projected for 57-59% of the species. Depending on the scenario, losses could be of 38-44% on average. The suitable areas for species were projected to shift, on average, 4.7-6.6° north and 3.9-5.4° east. Cold-adapted species were projected to lose climatically suitable areas, while gains were expected for warm-adapted species. When projections were analysed for different species groupings, only endemics stood out as a particular group. That is, endemics were projected to lose significantly larger amounts of suitable climatic areas than nonendemic species. Despite the uncertainties involved in modelling exercises such as this, the extent of projected distributional changes reveals further the vulnerability of freshwater organisms to climate change and implies a need to understand the consequences for ecological function and biodiversity conservation.
This study was designed to test for synergism (increased stress) or antagonism (decreased stress) among multiple environmental stressors using additive, multiplicative, and simple comparative effects models. Model predictions were compared to empirical results of laboratory experiments measuring interactions among thermal stress, toxin exposure, and low food on reproduction and survival of two species of cladoceran zooplankton. Stress was defined operationally as a reduction in reproduction or survival relative to optimal conditions over a 7-d period. These experiments are particularly applicable to episodic stresses such as those associated with short-term heat waves. Toxin or low food in combination with 30°C temperatures were generally more harmful than high temperature alone. However, most multiple stress effects were antagonistic, in that effects in combination were not as severe as predicted based on the sum or the product of their individual effects. In rare cases, interaction among stressors even diminished effects of the worst single stressor. Optimal conditions for reproduction and survival occurred at 25°C, high food and 0 mg liter-1 toxin (a surfactant, sodium dodecyl sulfate). Suppressive effects of stressors examined individually ranked: high temperature (30°C) > SDS (10 mg liter-1 ≥ low food (~100 μg C liter-1) > low temperature (20°C). Daphnia pulex isolated from a pond which experiences high summer temperatures throughout was more tolerant of 30°C conditions than Daphnia pulicaria isolated from a lake with a cold-water refuge. Differences were observed in individuals exposed as either adults or as 24-h neonates.
1. The fundamental importance of freshwater resources, the rapid extinction rate among freshwater species and the pronounced sensitivity of freshwater ecosystems to climate change together signal a pre-eminent need for renewed scientific focus and greater resources. Against this background, the Freshwater Biological Association in 2008 launched a new series of ‘summit’ Conferences in Aquatic Biology intended to develop and showcase the application of ecological science to major issues in freshwater management.
2. This collection of studies arose from the first summit entitled ‘Multiple Stressors in Freshwater Ecosystems’. Although freshwater science and management are replete with mutiple-stressor problems, few studies have been designed explicitly to untangle their effects.
3. The individual case studies that follow reveal the wide array of freshwaters affected by multiple stressors, the spatial and temporal scales involved, the species and ecosystem processes affected, the complex interactions between ecology and socioeconomics that engender such effects, the approaches advocated to address the problems and the challenges of restoring affected systems. The studies also illustrate the extent to which new challenges are emerging (e.g. through climate change), but also they develop a vision of how freshwaters might be managed sustainably to offset multiple stressors in future.
4. More generically, these case studies illustrate (i) how freshwaters might be at particular risk of multiple-stressor effects because of conflicts in water use, and because the hydrological cycle vectors stressor effects so effectively and so extensively; (ii) that dramatic, nonlinear, ‘ecological surprises’ sometimes emerge as multiple-stressor effects develop and (iii) that good ecology and good ecologists add considerable value to other freshwater disciplines in understanding multiple stressors and managing their effects.
1. Methods are needed to relate changing river flows to ecological response, particularly those which do not require collection of extensive new data for river segments that lack historical data. Using time‐series of river biomonitoring data from wadeable lowland streams in Denmark and the East Midlands of the U.K., we describe how local‐scale habitat features (indexed through River Habitat Survey or Danish Habitat Quality Survey) and changing river flow (discharge) influence the response of a macroinvertebrate community index. The approach has broad applicability in developing regional flow‐ecological response models.
2. We analysed the data using multilevel linear regression, combining sample‐level and site‐level characteristics as predictors. We focused on the potential for common responses across sites; hence for each sample, the macroinvertebrate community was summarised into an index, Lotic Invertebrate index for Flow Evaluation (LIFE), an average of abundance‐weighted flow groups which indicate the microhabitat preferences of each taxon for higher velocities and clean gravel/cobble substrata or slow/still velocities and finer substrata.
3. For the Danish fauna, the LIFE score responded to three predictors in an additive manner: high flows in the preceding 4 months (positive), substratum composition and whether the channel was meandering or straight. The East Midlands fauna responded to three predictors: high and low flows in the preceding 6 months (positive) and the degree of resectioning of the channel (negative). In both cases, LIFE responded negatively to features associated with historical channel modification. We suggest that there are several mechanisms for these relationships, including the narrower tolerances of taxa preferring high velocity habitat; these taxa are also continually recovering from extreme flow events over an inter‐annual timescale.
4. At the East Midlands sites, there was an interaction between degree of resectioning and antecedent low flow. At sites with a greater extent of resectioning, the LIFE‐discharge relationship was also steeper than at less modified sites. Consideration of the underlying data suggests that there are two mechanisms for this response. Firstly, in less modified sites, refugia are present during low flows for taxa preferring higher velocities such as riffle beetles, caseless caddis, mayflies and Gammarus pulex . Secondly, high flows are associated with decreasing abundances of taxa such as molluscs, flatworms and leeches at more resectioned sites, but with stable or increasing abundances at less modified sites.
5. The LIFE index responded to both antecedent flow and habitat modification in two separate data sets from lowland wadeable streams. This is the first time that the combined importance of these two factors has been demonstrated using routine invertebrate biomonitoring data. These results complement other site‐specific studies that have shown how channel structure interacts with flow to create physical habitat, and should assist future work aiming to define flow‐habitat‐biota relationships.
6. The derived models may be used to help guide environmental flow allocations, for example by predicting the slope of response of LIFE score to flow for comparable new locations which lack biological data.
This paper summarizes the development process and main characteristics of the Representative Concentration Pathways (RCPs), a set of four new scenarios developed for the climate modeling community as a basis for long-term and near-term modeling experiments. The four RCPs together span the range of year 2100 radiative forcing values found in the open literature, i.e. from 2.6 to 8.5 W/m2. The RCPs are the product of an innovative collaboration between integrated assessment modelers, climate modelers, terrestrial ecosystem modelers and emission inventory experts. The resulting product forms a comprehensive data set with high spatial and sectoral resolutions for the period extending to 2100. Land use and emissions of air pollutants and greenhouse gases are reported mostly at a 0.5 x 0.5 degree spatial resolution, with air pollutants also provided per sector (for well-mixed gases, a coarser resolution is used). The underlying integrated assessment model outputs for land use, atmospheric emissions and concentration data were harmonized across models and scenarios to ensure consistency with historical observations while preserving individual scenario trends. For most variables, the RCPs cover a wide range of the existing literature. The RCPs are supplemented with extensions (Extended Concentration Pathways, ECPs), which allow climate modeling experiments through the year 2300. The RCPs are an important development in climate research and provide a potential foundation for further research and assessment, including emissions mitigation and impact analysis.
Streams in mediterranean regions have highly seasonal discharge patterns, with predictable torrential floods and severe droughts. In contrast, discharge is less variable in temperate regions and intermittent flow conditions are uncommon. Hydroclimatic models predict that climate change would increase frequency and severity of floods and droughts across Europe, thus increasing the proportion of streams with mediterranean characteristics in actually temperate areas. Correspondingly, understanding actual ecological differences between mediterranean and temperate streams may help to anticipate large-scale ecological impacts of climate change. Given that large-scale factors determine local community composition, we hypothesized that climatic differences between mediterranean and temperate regions should affect the taxonomic and biological trait composition in streams. We assembled the abundance of stream macroinvertebrate genera of 265 sites each from the Mediterranean Basin and from temperate Europe and linked these abundances to published information on 61 categories of 11 biological traits reflecting the potential of resilience from and resistance to disturbances. Although regional taxonomic richness was higher in the mediterranean than in the temperate region, local taxonomic richness and diversity did not significantly differ between regions. Local trait richness and diversity were significantly higher in the mediterranean region. Both local taxonomic and trait-community composition differed between regions, but the former varied much more than the latter, highlighting that climate change could produce large changes in the taxonomic but rather weak changes in the trait composition. The mediterranean region was characterized by macroinvertebrates with higher dispersion and colonization capabilities, suggesting that species loss in the temperate region, by extinction or northward emigration of taxa, would be compensated for by immigration of southern mediterranean taxa. Thus, climate change would likely have stronger implications for the local conservation of taxa than for the trait composition of stream macroinvertebrate communities.
With the EC Water Framework Directive (WFD) the ecological status of a water body is defined by comparing the observed biological community composition present with near-natural reference conditions. The ecological status is then classified into five quality classes (high, good, moderate, poor and bad). It is of great importance that `good ecological status' has the same meaning within the European Union, since water bodies not measuring up to these standards have to be improved. Therefore, the Ecological Quality Ratios (EQR) at high-good, and good-moderate quality class boundaries will be intercalibrated. Each country has to report physical, chemical, and biological data from two sites at each of these boundaries and since most data exist for benthic macroinvertebrates, this quality element will be of great importance in the intercalibration process. The aim of this study was therefore to compare the results of different benthic macroinvertebrate metrics used to assess the impact of organic pollution (including eutrophication) (one of the major human impacts on European streams). A selection of the data sampled in the AQEM project was evaluated, where benthic macroinvertebrate- and abiotic data from four countries (Austria, the Czech Republic, Portugal and Sweden) and seven `stream types' were included. An organic pollution (including eutrophication) gradient was defined using Principal Component Analysis and the boundaries for high-good and good-moderate ecological status set by the partners from each country were used to define arbitrary class boundaries. The Average Score Per Taxon (ASPT) was well correlated with the stress gradient in most stream types, whereas the Saprobic Index worked clearly better than ASPT in those countries (Austria and the Czech Republic) where macroinvertebrates are generally identified to lower (species) as opposed to a higher (genus or family) level of identification. Defining harmonised class boundaries is difficult; this process has to consider the natural differences between stream types (e.g. in the reference values of metrics) but has to eliminate different perceptions of ecological quality.
Comprehensive knowledge of the effects of disturbances on biodiversity is crucial for conservation and management, not least because ecosystems with low biodiversity may be the most vulnerable. In rivers, the role of disturbance in shaping aquatic biodiversity has mainly focused on floods. Perennial rivers (PRs) often flood, whereas intermittent rivers (IRs) flood, stop flowing and dry. Despite the recent and significant increase in research on IRs, controversy remains about whether they are more or less biodiverse than PRs. Our aim was to determine (Q1) if PRs and IRs differ in biodiversity and (Q2) if the direction and magnitude of the differences (effect sizes) are related to environmental (climate, season, habitat, longitudinal zonation and anthropogenic disturbance) and/or biological factors (taxonomic group). We conducted a meta-analysis on 44 published studies of PR and IR biodiversity that had replicated data. We applied random effects models to the data to obtain weighted mean effect sizes for differences between PRs and IRs, and their confidence intervals, by first considering all studies and then by splitting studies into groups on the basis of the above factors. We found that biodiversity was significantly higher in PRs than in IRs (Q1). We also detected significant differences (PRs>IRs) in studies of macroinvertebrates, in those conducted within arid and temperate climates, dry and wet sampling seasons, headwaters, and regions subject to different levels of anthropogenic disturbance (Q2). Our meta-analysis suggests that the expected increase in the prevalence of IRs in certain regions of the world due to global change could result in a decrease in freshwater biodiversity. To better manage and preserve aquatic biodiversity under future global change scenarios and to avoid potential ecosystem consequences of biodiversity loss, conservation efforts should be targeted towards those environmental conditions or taxonomic groups with significant differences (PRs>IRs). This article is protected by copyright. All rights reserved.
Mediterranean catchments experience already high seasonal variability alternating between dry and wet periods, and are more vulnerable to future climate and land use changes. Quantification of catchment response under future changes is particularly crucial for better water resources management. This study assessed the combined effects of future climate and land use changes on water yield, total nitrogen (TN) and total phosphorus (TP) loads of the Mediterranean Onkaparinga catchment in South Australia by means of the eco-hydrological model SWAT. Six different global climate models (GCMs) under two representative concentration pathways (RCPs) and a hypothetical land use change were used for future simulations. The climate models suggested a high degree of uncertainty, varying seasonally, in both flow and nutrient loads; however, a decreasing trend was observed. Average monthly TN and TP load decreased up to − 55% and − 56% respectively and were found to be dependent on flow magnitude. The annual and seasonal water yield and nutrient loads may only slightly be affected by envisaged land uses, but significantly altered by intermediate and high emission scenarios, predominantly during the spring season. The combined scenarios indicated the possibility of declining flow in future but nutrient enrichment in summer months, originating mainly from the land use scenario, that may elevate the risk of algal blooms in downstream drinking water reservoir. Hence, careful planning of future water resources in a Mediterranean catchment requires the assessment of combined effects of multiple climate models and land use scenarios on both water quantity and quality.
Water resources globally are affected by a complex mixture of stressors resulting from a range of drivers, including urban and agricultural land use, hydropower generation and climate change. Understanding how stressors interfere and impact upon ecological status and ecosystem services is essential for developing effective River Basin Management Plans and shaping future environmental policy. This paper details the nature of these problems for Europe's water resources and the need to find solutions at a range of spatial scales. In terms of the latter, we describe the aims and approaches of the EU-funded project MARS (Managing Aquatic ecosystems and water Resources under multiple Stress) and the conceptual and analytical framework that it is adopting to provide this knowledge, understanding and tools needed to address multiple stressors. MARS is operating at three scales: At the water body scale, the mechanistic understanding of stressor interactions and their impact upon water resources, ecological status and ecosystem services will be examined through multi-factorial experiments and the analysis of long time-series. At the river basin scale, modelling and empirical approaches will be adopted to characterise relationships between multiple stressors and ecological responses, functions, services and water resources. The effects of future land use and mitigation scenarios in 16 European river basins will be assessed. At the European scale, large-scale spatial analysis will be carried out to identify the relationships amongst stress intensity, ecological status and service provision, with a special focus on large transboundary rivers, lakes and fish. The project will support managers and policy makers in the practical implementation of the Water Framework Directive (WFD), of related legislation and of the Blueprint to Safeguard Europe's Water Resources by advising the 3rd River Basin Management Planning cycle, the revision of the WFD and by developing new tools for diagnosing and predicting multiple stressors.
Climate change may influence hydrologic processes of watersheds (IPCC, 2013) and increased runoff may cause flooding, eroded stream banks, widening of stream channels, increased pollutant loading, and consequently impairment of aquatic life. The goal of this study was to quantify the potential impacts of climate change on watershed hydrologic processes and to evaluate scale and effectiveness of management practices for adaptation. We simulate baseline watershed conditions using the Hydrological Simulation Program Fortran (HSPF) simulation model to examine the possible effects of changing climate on watershed processes. We also simulate the effects of adaptation and mitigation through specific best management strategies for various climatic scenarios. With continuing low-flow conditions and vulnerability to climate change, the Ipswich watershed is the focus of this study. We quantify fluxes in runoff, evapotranspiration, infiltration, sediment load, and nutrient concentrations under baseline and climate change scenarios (near and far future). We model adaptation options for mitigating climate effects on watershed processes using bioretention/raingarden Best Management Practices (BMPs). It was observed that climate change has a significant impact on watershed runoff and carefully designed and maintained BMPs at subwatershed scale can be effective in mitigating some of the problems related to stormwater runoff. Policy options include implementation of BMPs through education and incentives for scale-dependent and site specific bioretention units/raingardens to increase the resilience of the watershed system to current and future climate change.
The potential regional future changes in seasonal (winter and summer) temperature and precipitation are assessed for the greater area of Greece over the 21st century, under A2, A1B and B2 future emission scenarios of IPCC. Totally twenty-two simulations from various regional climate models (RCMs) were assessed; fourteen of them with a spatial grid resolution of 50km for the period 2071-2100 under A2 (9 simulations) and B2 (5 simulations) scenarios and eight of them with an even finer resolution of 25km under A1B scenario for both 2021-2050 and 2071-2100 time periods. The future changes in temperature and precipitation were calculated with respect to the control period (1961-1990). All the models estimated warmer and dryer conditions over the study area. The warming is more intense during the summer months, with the changes being larger in the continental than in the marine area of Greece. In terms of precipitation, the simulations of the RCMs estimate a decrease up to -60% (A2 scenario). Finally it is shown that the changes in the atmospheric circulation over Europe play a key role in the changes of the future precipitation and temperature characteristics over the domain of study in a consistent way for the different emission scenarios.
Global warming has accelerated in recent years with an increase of about 0.75°C during the past 100 years. The rate of temperature increase in the past 25 years has been over 0.18°C per decade. Global warming has been observed more over land than over the ocean. This rise in temperature is leading to a rise in sea levels, glacier melt, and changes in precipitation patterns. In addition to urbanisation where roads and buildings impact on the amount of groundwater percolation, large infrastructures such as dams are impacting on the microclimate cycle, which changes the evapotranspiration rate in the region leading to a change in the amount of precipitation. The focus of this chapter is on the impact of climate change on the water cycle, particularly in relation to freshwater, including how a change in the climate cycle is impacting on the water cycle, followed by the impacts of change on water quality and availability, health, agriculture (food security), biodiversity, and water security.
Assessment of future precipitation variations prevailing in an area is essential for the research regarding climate and climate change. The current paper focuses on 3 selected areas in Greece that present different climatic characteristics due to their location and aims to assess and compare the future variation of annual and seasonal precipitation. Future precipitation data from the ENSEMBLES anthropogenic climate-change (ACC) global simulations and the Climate Local Model (CLM) were obtained and analyzed. The climate simulations were performed for the future periods 2021-2050 and 2071-2100 under the A1B and B1 scenarios. Mann-Kendall test was applied to investigate possible trends. Spatial distribution of precipitation was performed using a combination of dynamic and statistical downscaling technique and Kriging method within ArcGIS 10.2.1. The results indicated that for both scenarios, reference periods and study areas, precipitation is expected to be critically decreased. Additionally, Mann-Kendall test application showed a strong downward trend for every study area. Furthermore, the decrease in precipitation for the Ardas River basin characterised by the continental climate will be tempered, while in the Sperchios River basin it will be smoother due to the influence of some minor climatic variations in the basins' springs in the highlands where milder conditions occur. Precipitation decrease in the Geropotamos River basin which is characterized by Mediterranean climate will be more vigorous. B1 scenario is appeared more optimistic for the Ardas and Sperchios River basins, while in the Geropotamos River basin, both applied scenarios brought similar results, in terms of future precipitation response.
Protecting the worlds freshwater resources requires diagnosing threats over a broad range of scales, from global to local. Here we present the first worldwide synthesis to jointly consider human and biodiversity perspectives on water security using a spatial framework that quantifies multiple stressors and accounts for downstream impacts. We find that nearly 80% of the worlds population is exposed to high levels of threat to water security. Massive investment in water technology enables rich nations to offset high stressor levels without remedying their underlying causes, whereas less wealthy nations remain vulnerable. A similar lack of precautionary investment jeopardizes biodiversity, with habitats associated with 65% of continental discharge classified as moderately to highly threatened. The cumulative threat framework offers a tool for prioritizing policy and management responses to this crisis, and underscores the necessity of limiting threats at their source instead of through costly remediation of symptoms in order to assure global water security for both humans and freshwater biodiversity.
Catchment flow regimes alteration is likely to be a prominent consequence of climate change projections in the Mediterranean. Here we explore the potential effects of climatic change on the flow regime of the Thau and the Chiba catchments which are located in Southern France and Northeastern Tunisia, respectively. The Soil and Water Assessment Tool (SWAT) hydrological model is forced with projections from an ensemble of 4 climate model (CM) to assess changes and uncertainty in relevant hydrological indicators related to water balance, magnitude, frequency and timing of the flow between a reference (1971-2000) and future (2041-2071) periods. Results indicate that both catchments are likely to experience a decrease in precipitation and increase in temperature in the future. Consequently, runoff and soil water content are projected to decrease whereas potential evapotranspiration is likely to increase in both catchments. Yet uncertain, the projected magnitudes of these changes are higher in the wet period than in the dry period. Analyses of extreme flow show similar trend in both catchments, projecting a decrease in both high flow and low flow magnitudes for various time durations. Further, significant increase in low flow frequency as a proxy for hydrological droughts is projected for both catchments but with higher uncertainty in the wet period than in the dry period. Although no changes in the average timing of maximum and minimum flow events for different flow durations are projected, substantial uncertainty remains in the hydrological projections. While the results in both catchments show consistent trend of change for most of the hydrologic indicators, the overall degree of alteration on the flow regime of the Chiba catchment is projected to be higher than that of the Thau catchment. The projected magnitudes of alteration as well as their associated uncertainty vary depending on the catchment characteristics and flow seasonality.
Climate variability due to the greenhouse effect has important implications on hydrological processes and water resources systems. Indeed, water availability, quality and streamflow are very sensitive to changes in temperature and precipitation regimes whose effects have to be fully considered in current water management and planning. International literature proposes several models, attempting to assess accurately the available water resources under stationary and changing climatic conditions at different spatial and temporal scales. In order to assess the potential impacts of climate change on surface and groundwater resources water availability in a Southern area of Italy, a conceptual hydrologic model, the TOPDM, was applied at daily scale to simulate the hydrological processes in the Belice river basin, located in Sicily and which feeds an artificial lake. The analysis of climatic forcings trend provided the parameters needed in order to generate synthetic climate forcing series through the use of the AWE-GEN, an hourly weather generator, able to reproduce the characteristics of hydro-climatic variables and their statistical properties. . The hydrological model was used to estimate the basin water balance components and the surface and groundwater availability, at annual and monthly scale, in a no trend scenario, representing the current climate conditions, and in three different groups of scenarios, in which a decrease of precipitation, an increase of temperature, and a combination of these effect were reproduced. The application of TOPDM to the test basin provided some important conclusions about the implications of climate change in the Southern part of Italy. Results showed that runoff and evapotranspiration reflect variations in precipitation and in temperature; in particular the negative trend in precipitation determines a decrease in surface and groundwater resources, and this effect is intensified in the scenarios that include an increase in potential evapotraspiration as well. The consequences of changes on water supply system were also analyzed through a simple balance evaluation of the lake water reservoir, in order to assess the possible impacts on the resource managements. Results indicated an exacerbation of the water resources stresses, in which water scarcity is already an important issue for water resource management. The analysis provides useful information about the quantification of the potential effects of climate change in the area of study, in order to develop new strategies to deal with these changes.
Streams and rivers in mediterranean-climate regions (med-rivers in med-regions) are ecologically unique, with flow regimes reflecting precipitation patterns. Although timing of drying and flooding is predictable, seasonal and annual intensity of these events is not. Sequential flooding and drying, coupled with anthropogenic influences make these med-rivers among the most stressed riverine habitat worldwide. Med-rivers are hotspots for biodiversity in all med-regions. Species in med-rivers require different, often opposing adaptive mechanisms to survive drought and flood conditions or recover from them. Thus, metacommunities undergo seasonal differences, reflecting cycles of river fragmentation and connectivity, which also affect ecosystem functioning. River conservation and management is challenging, and trade-offs between environmental and human uses are complex, especially under future climate change scenarios. This overview of a Special Issue on med-rivers synthesizes information presented in 21 articles covering the five med-regions worldwide: Mediterranean Basin, coastal California, central Chile, Cape region of South Africa, and southwest and southern Australia. Research programs to increase basic knowledge in less-developed med-regions should be prioritized to achieve increased abilities to better manage med-rivers.
Socio-economic scenarios constitute an important tool for exploring the long-term consequences of anthropogenic climate change and available response options. A more consistent use of socio-economic scenarios that would allow an integrated perspective on mitigation, adaptation and residual climate impacts remains a major challenge. We assert that the identification of a set of global narratives and socio-economic pathways offering scalability to different regional contexts, a reasonable coverage of key socio-economic dimensions and relevant futures, and a sophisticated approach to separating climate policy from counter-factual "no policy" scenarios would be an important step toward meeting this challenge. To this end, we introduce the concept of "shared socio-economic (reference) pathways". Sufficient coverage of the relevant socio-economic dimensions may be achieved by locating the pathways along the dimensions of challenges to mitigation and to adaptation. The pathways should be specified in an iterative manner and with close collaboration between integrated assessment modelers and impact, adaptation and vulnerability researchers to assure coverage of key dimensions, sufficient scalability and widespread adoption. They can be used not only as inputs to analyses, but also to collect the results of different climate change analyses in a matrix defined by two dimensions: climate exposure as characterized by a radiative forcing or temperature level and socio-economic development as classified by the pathways. For some applications, socio-economic pathways may have to be augmented by "shared climate policy assumptions" capturing global components of climate policies that some studies may require as inputs. We conclude that the development of shared socio-economic (reference) pathways, and integrated socio-economic scenarios more broadly, is a useful focal point for collaborative efforts between integrated assessment and impact, adaptation and vulnerability researchers.
Extensive degradation of ecosystems, combined with the increasing demands placed on the goods and services they provide, is a major driver of biodiversity loss on a global scale. In particular, the severe degradation of large rivers, their catchments, floodplains and lower estuarine reaches has been ongoing for many centuries, and the consequences are evident across Europe. River restoration is a relatively recent tool that has been brought to bear in attempts to reverse the effects of habitat simplification and ecosystem degradation, with a surge of projects undertaken in the 1990s in Europe and elsewhere, mainly North America. Here, we focus on restoration of the physical properties (e.g. substrate composition, bank and bed structure) of river ecosystems to ascertain what has, and what has not, been learned over the last 20 years.
A central aspect of the Water Framework Directive 2000/60/EC addressed to Member Countries is to proceed to type-specific ecological assessment and classification by establishing typology systems. Sixty-four permanent stream sites distributed throughout mainland Greece and islands were assessed with macroinvertebrate indicators to evaluate their ecological quality. Local and catchment scale parameters were determined and recorded to obtain an integrated assessment of the main factors affecting stream integrity and macroinvertebrate communities. Twenty-three sites were classified as reference or good status in terms of biological, chemical and hydromorphological quality with the use of various metrics. Multivariate statistical techniques were performed (MDS, BIOENV, correlation analysis and PCA) to investigate the main environmental factors structuring benthic macroinvertebrate communities and to select candidate environmental variables for establishing a biotic typology for Hellenic rivers. The results revealed relatively distinct macroinvertebrate communities within defined abiotic zones of the country. Assemblages of macroinvertebrate fauna were most strongly associated to differences in geographical position, altitude, slope, catchment area, current velocity, conductivity and water temperature. In view of the lack of sufficient data at the country level on the three last variables and after considering cause–effect relationships between large scale variables and the latter, it has been demonstrated that a number of catchment scale variables could be used as robust surrogates.
Two-dimensional hydrodynamic models are being used increasingly as alternatives to traditional one-dimensional instream flow methodologies for assessing adequacy of flow and associated faunal habitat. Two-dimensional modelling of habitat has focused primarily on fishes, but fish-based assessments may not model benthic macroinvertebrate habitat effectively. We extend two-dimensional techniques to a macroinvertebrate assemblage in a high-elevation stream in the Sierra Nevada (Dana Fork of the Tuolumne River, Yosemite National Park, CA, USA). This stream frequently flows at less than 0.03 m3 s−1 in late summer and is representative of a common water abstraction scenario: maximum water abstraction coinciding with seasonally low flows. We used two-dimensional modelling to predict invertebrate responses to reduced flows that might result from increased abstraction. We collected site-specific field data on the macroinvertebrate assemblage, bed topography and flow conditions and then coupled a two-dimensional hydrodynamic model with macroinvertebrate indices to evaluate habitat across a range of low flows. Macroinvertebrate indices were calculated for the wetted area at each flow. A surrogate flow record based on an adjacent watershed was used to evaluate frequency and duration of low flow events. Using surrogate historical records, we estimated that flow should fall below 0.071 m3 s−1 at least 1 day in 82 of 95 years and below 0.028 m3 s−1 in 48 of 95 years. Invertebrate metric means indicated minor losses in response to modelled discharge reductions, but wetted area decreased substantially. Responses of invertebrates to water abstraction will likely be a function of changing habitat quantity rather than quality. Copyright © 2011 John Wiley & Sons, Ltd.
Compared to other ecosystem types, a wide variety of biomonitoring methods are available for rivers. Few studies have, however, compared the response of bioindicators (i.e. different river inhabiting taxonomic groups) to different types of environmental stress.
We regressed diversity, taxonomic distinctness and assemblage composition of fish, invertebrates, macrophytes and benthic diatoms to multivariate gradients in nutrient enrichment and habitat degradation using data from 66 lowland and 77 mountain streams.
In lowland streams, the composition of benthic diatom assemblages, measured by Detrended Correspondence Analysis, showed the strongest response to elevated nutrient concentrations ( R ² = 0·830), followed by macrophytes (0·711), fish (0·443) and invertebrates (0·391). Macrophyte richness was slightly better correlated with the habitat gradient (0·253) than diatom richness (0·235) and both were better predictors than either fish (0·147) or invertebrate (0·140) assemblage composition.
For mountain streams, invertebrate assemblage composition was the best predictor of changes in nutrient concentrations ( R ² = 0·749), followed by macrophyte (0·396) and benthic diatom (0·325) assemblages and fish diversity (0·099). Invertebrate assemblage composition was also slightly better correlated with the habitat gradient (0·391) compared to macrophyte richness (0·323) and both were better than either benthic diatom assemblage composition (0·206) or fish abundance (0·161).
Macrophyte and benthic diatom assemblages in lowland streams and fish and invertebrate assemblages in mountain streams were correlated with the other taxonomic groups, implying that these taxonomic groups may be used as surrogates for indicating wholesale change in diversity.
Synthesis and applications . Our findings show that response trajectories differ between taxonomic groups and stressor, and even with stream type. For this reason, streams and other ecosystem type's response signatures and first and second principle relations should be considered in the selection of robust, complementary and cost‐effective measures for biomonitoring. For instance, our findings of asymmetric response to stress show how different taxonomic groups can be used to strengthen inference of change.
Key Words flooding, drying, human impact s Abstract Streams in mediterranean-climate regions (areas surrounding the Mediterranean Sea, parts of western North America, parts of west and south Australia, southwestern South Africa and parts of central Chile) are physically, chemically, and biologically shaped by sequential, predictable, seasonal events of flooding and drying over an annual cycle. Correspondingly, aquatic communities undergo a yearly cycle whereby abiotic (environmental) controls that dominate during floods are reduced when the discharge declines, which is also a time when biotic controls (e.g. predation, compe-tition) can become important. As the dry season progresses, habitat conditions become harsher; environmental pressures may again become the more important regulators of stream populations and community structure. In contrast to the synchronous input of autumn litterfall in forested temperate streams, riparian input to mediterranean-type streams is more protracted, with fall and possibly spring peaks occurring in streams in the Northern Hemisphere and a summer peak existing in their Southern Hemisphere counterparts. We present 25 testable hypotheses that relate to the influence of the stream hydrograph on faunal richness, abundance, and diversity; species coexistence; seasonal changes in the relative importance of abiotic and biotic controls on the bi-otic structure; riparian inputs and the relative importance of heterotrophy compared to autotrophy; and the impact of human activities on these seasonally water-stressed streams. Population increases in mediterranean-climate regions (particularly in fer-tile regions) result in an intensification of the competition for water among different users; consequently, water abstraction, flow regulation, increased salinity, and pollu-tion severely limit the ability of the streams to survive as sustainable, self-regulated systems.
Two types of modification of the hydrological system are present in the same regulated segment of the Lima River (NW Portugal): (a) a reduced and constant flow from hypolimnetic release; (b) an intense irregular flow (daily and seasonal). Using multivariate techniques it was possible to compare the effects of these two kinds of disturbance on the macroinvertebrate communities. The communities colonizing both sites exhibited a higher variation in composition and diversity when compared to undisturbed sites. However, such variability was even more evident in the first case, in spite of the stability of the environmental conditions. Such temporal replacement of species is linked to the dominance of tolerant taxa with short life cycles. In the regulated segment the poor water quality and the lack of litter input impacted mainly on the shredders group. This work shows the failure of the practice of releasing constant flows as an attempt to mitigate regulation impacts.
1. This study investigated the relation of benthic macroinvertebrates to environmental gradients in Central European lowland rivers. Taxonomic structure (taxa) and functional composition (metrics) were related to gradients at four different spatial scales (ecoregion, catchment, reach and site). The environmental variables at the catchment‐, reach‐ and site scales reflected the intensity of human impact: catchment and floodplain land use, riparian and floodplain degradation, flow regulation and river bank and bed modification.
2. Field surveys and GIS yielded 130 parameters characterising the hydromorphology and land use of 75 river sections in Sweden, the Netherlands, Germany and Poland. Two hundred and forty‐four macroinvertebrate taxa and 84 derived community metrics and biotic indices such as functional guilds, diversity and composition measures were included in the analysis.
3. Canonical Correspondence Analysis (CCA) and Redundancy Analysis (RDA) showed that hydromorphological and land use variables explained 11.4%, 22.1% and 15.8% of the taxa variance at the catchment (‘macro’), reach (‘meso’) and site (‘micro’) scales, respectively, compared with 14.9%, 33.2% and 21.5% of the variance associated with the derived metrics. Ecoregion and season accounted for 10.9% and 20.5% of the variance of the taxonomic structure and functional composition, respectively.
4. Partial CCA (pCCA) and RDA (pRDA) showed that the unique variance explained was slightly higher for taxa than for metrics. By contrast, the joint variance explained for metrics was much higher at all spatial scales and largest at the reach scale. Environmental variables explained 46.8% of metric variance and 32.4% of taxonomic structure.
5. Canonical Correspondence Analysis and RDA identified clear environmental gradients along the two main ordination axes, namely, land use and hydromorphological degradation. The impact of catchment land use on benthic macroinvertebrates was mainly revealed by the proportion of urban areas. At the reach scale, riparian and floodplain attributes (bank fixation, riparian wooded vegetation, shading) and the proportion of large woody debris were strong predictors of the taxonomic structure and functional composition of benthic macroinvertebrates. At the site scale, artificial substrata indicated human impact, particularly the proportion of macro‐ and mesolithal used for bank enforcement (rip–rap).
6. Our study revealed the importance of benthic macroinvertebrate functional measures (functional guilds, composition and abundance measures, sensitivity and tolerance measures, diversity measures) for detecting the impact of hydromorphological stress at different spatial scales.
Recent and potential future increases in global temperatures are likely to be associated with impacts on the hydrologic cycle,
including changes to precipitation and increases in extreme events such as droughts. We analyze changes in drought occurrence
using soil moisture data for the SRES B1, A1B and A2 future climate scenarios relative to the PICNTRL pre-industrial control
and 20C3M twentieth century simulations from eight AOGCMs that participated in the IPCC AR4. Comparison with observation forced
land surface model estimates indicates that the models do reasonably well at replicating our best estimates of twentieth century,
large scale drought occurrence, although the frequency of long-term (more than 12-month duration) droughts are over-estimated.
Under the future projections, the models show decreases in soil moisture globally for all scenarios with a corresponding doubling
of the spatial extent of severe soil moisture deficits and frequency of short-term (4–6-month duration) droughts from the
mid-twentieth century to the end of the twenty-first. Long-term droughts become three times more common. Regionally, the Mediterranean,
west African, central Asian and central American regions show large increases most notably for long-term frequencies as do
mid-latitude North American regions but with larger variation between scenarios. In general, changes under the higher emission
scenarios, A1B and A2 are the greatest, and despite following a reduced emissions pathway relative to the present day, the
B1 scenario shows smaller but still substantial increases in drought, globally and for most regions. Increases in drought
are driven primarily by reductions in precipitation with increased evaporation from higher temperatures modulating the changes.
In some regions, increases in precipitation are offset by increased evaporation. Although the predicted future changes in
drought occurrence are essentially monotonic increasing globally and in many regions, they are generally not statistically
different from contemporary climate (as estimated from the 1961–1990 period of the 20C3M simulations) or natural variability
(as estimated from the PICNTRL simulations) for multiple decades, in contrast to primary climate variables, such as global
mean surface air temperature and precipitation. On the other hand, changes in annual and seasonal means of terrestrial hydrologic
variables, such as evaporation and soil moisture, are essentially undetectable within the twenty-first century. Changes in
the extremes of climate and their hydrological impacts may therefore be more detectable than changes in their means.