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Water shortages worsened by reservoir effects
Abstract
The expansion of reservoirs to cope with droughts and water shortages is hotly debated in many places around the world. We argue that there are two counterintuitive dynamics that should be considered in this debate: supply–demand cycles and reservoir effects. Supply–demand cycles describe instances where increasing water supply enables higher water demand, which can quickly offset the initial benefits of reservoirs. Reservoir effects refer to cases where over-reliance on reservoirs increases vulnerability, and therefore increases the potential damage caused by droughts. Here we illustrate these counterintuitive dynamics with global and local examples, and discuss policy and research implications.
... This is a vicious circle. As water demands are met, new ones are generated in anticipation of new water resources (Molle 2008;Gohari et al. 2013;Wanders and Wada 2015;Di Baldassarre et al. 2018). The construction of dams, reservoirs and major diversion projects, the exploitation of groundwater or the use of cutting-edge irrigation technologies such as saltwater desalination or brackish groundwater desalination, have been unable to close the gap between available water and current and future water needs (Paul et al. 2019). ...
... Globally, although developing countries still have prime locations for building new dams (Gray and Sadoff 2006), the best sites on which to build dams have already been tapped as shown by the S-shaped curve of the evolution of water storage (Di Baldassarre et al. 2018). The reservoir capacity grew at a very good rate during the 1960s compared to demand growth (300% versus 15%, respectively), but in more recent decades the dynamics have reversed, and demand has grown faster (20%) than storage capacity (2%) (Di Baldassarre et al. 2018). ...
... Globally, although developing countries still have prime locations for building new dams (Gray and Sadoff 2006), the best sites on which to build dams have already been tapped as shown by the S-shaped curve of the evolution of water storage (Di Baldassarre et al. 2018). The reservoir capacity grew at a very good rate during the 1960s compared to demand growth (300% versus 15%, respectively), but in more recent decades the dynamics have reversed, and demand has grown faster (20%) than storage capacity (2%) (Di Baldassarre et al. 2018). ...
The divergence between agricultural water use and the annual supply of water resources (water gap) has been increasing for decades. The forecast is that this water gap will continue to widen, compromising the water security of a large share of the global population. On the one hand, the increase in demand is attributed to an ever-growing population that, in addition, is adopting a high-water consumption per capita lifestyle (e.g., meat-rich diet, increased use of biofuels and of irrigated agriculture). On the other hand, climate change is increasing aridification and the spatio-temporal heterogeneity of precipitation worldwide. The water gap is particularly acute in drylands, where development and food security has been based on the massive exploitation of water resources, particularly groundwater. Here we analyze the mechanisms underlying this water gap, which is mainly driven by water use in agriculture, and suggest suitable solutions that can help to close it. Using causal diagrams, we show how population generates different demands that create a water gap that prevailing supply-side solutions cannot close. Indeed, it has been widening over the years because water consumption has grown exponentially. This behaviour is explained by a series of mechanisms that it is necessary to understand to realize the complexity of water scarcity problems. For solving the water gap, we propose and exemplify eight lines of action that can be combined and tailored to each territory. Our analyses corroborate the urgent need to plan an integral management of water resources to avoid widespread scenarios of water scarcity under future climatic conditions.
... Moreover, negative feedback loops such as the supply-demand cycle, where increased water supply accelerates water use, can offset the initial benefits of reservoirs. Such negative feedback loops complicate drought adaptation and risk management (Di Baldassarre et al., 2018). However, two-way feedbacks between hydrological dynamics and human adaptive behavior are often neglected in drought analysis (Montanari et al., 2013;Bierkens, 2015;Van Loon et al., 2016;Wens et al., 2019). ...
... Studies have also found that risk appraisal is primarily shaped by recent harmful events (Gbetibouo, 2009;Rao et al., 2011). However, this awareness decreases over time (Di Baldassarre et al., 2018). Therefore, risk appraisal increases in relation to the relative damage experienced due to drought but decreases if no drought damage occurs. ...
... Most studies focus on the positive sides of adaptation, and how drought adaptation (e.g., irrigation) reduces drought risk. However, this research shows there can be negative unintended consequences from implementing drought adaptation measures that can emerge from the coevolution between water and human systems (Di Baldassarre et al., 2018;Ward et al., 2020). Alam et al. (2022) categorizes these unintended consequences into negative hydrological externalities and unexpected social feedbacks. ...
Drought is a persistent hazard that impacts the environment, people's livelihoods, access to education and food security. Adaptation choices made by people can influence the propagation of this drought hazard. However, few drought models incorporate adaptive behavior and feedbacks between adaptations and drought. In this research, we present a dynamic drought adaptation modeling framework, ADOPT-AP, which combines socio-hydrological and agent-based modeling approaches. This approach is applied to agropastoral communities in dryland regions in Kenya. We couple the spatially explicit hydrological Dryland Water Partitioning (DRYP) model with a behavioral model capable of simulating different bounded rational behavioral theories (ADOPT). The results demonstrate that agropastoralists respond differently to drought due to differences in (perceptions of) their hydrological environment. Downstream communities are impacted more heavily and implement more short-term adaptation measures than upstream communities in the same catchment. Additional drivers of drought adaptation concern socio-economic factors such as wealth and distance to wells. We show that the uptake of drought adaptation influences soil moisture (positively through irrigation) and groundwater (negatively through abstraction) and, thus, the drought propagation through the hydrological cycle.
... (Lehner et al., 2011). Large dam operations and resilience 25 to climate extremes have been studied at both the regional and national level (Adusumilli, Borsa, Fish, McMillan, & Silverii, 2019;Di Baldassarre et al., 2018). However, existing reservoir studies have been greatly limited by the lack of historical data. ...
... By regulating the flow of rivers, dams provide reliable water supplies, enable year-round navigation, protect communities against damaging floods, and support regional economic development (Benson, 2017;Boulange, Hanasaki, Yamazaki, & Pokhrel, 2021;Ho et al., 2017;Ortiz-Partida, Lane, & Sandoval-Solis, 2016;Patterson & Doyle, 2018). In fact, Finally, there is a strong reliance on reservoir systems to provide water supply, hydropower, and irrigation uses especially in more arid regions (Di Baldassarre et al., 2018). 50 ...
... Also, in recent years studies have begun to question the conventional wisdom that dams provide more reliable systems 65 particularly as we start to see climate extremes that fall outside what these systems were engineered for. It has been argued that large storage reservoirs in the western United States have actually increased regional sensitivity to climatic variabilities (particularly droughts) and has locked the region into potentially unsustainable water use (Adusumilli et al., 2019;Di Baldassarre et al., 2018). In part because the region is now reliant on a cumulative storage capacity that is one third of the total storage capacity in CONUS and has seen a large increase in water usage to support agriculture and population growth (Di 70 Baldassarre et al., 2018). ...
All major river systems in the Contiguous United States (CONUS) are impacted by dams. Many regional and global studies have looked at reservoir resilience to extreme events and quantified static characteristics, yet analysis of historical reservoir operations has been limited by a lack of data. Here we use the first national dataset of historical reservoir operations in CONUS, ResOpsUS, to analyze reservoir storage trends and operations over the last 40 years. We characterized seasonal operating patterns and show clear regional trends. In the eastern US which is dominated by flood control storage we see that storage peaks in the winter months with sharper decreases in operational range in the summer. While in the more arid western US where storage is predominantly for irrigation, we find that storage peaks during the spring and summer with increases in the operational range during the summer months. The Lower Colorado region is an outlier because it is arid and dominate by irrigation, but its seasonal storage dynamics more closely mirrored that of flood control basins. Consistent with previous studies we show that reservoir storage has decreased over the past 40 years, although our national fraction filled decreases are 50 % less than those shown previously. We also find that declines are occurring faster in more arid regions. Operational ranges (i.e. the difference between monthly max and min storage) have been increasing over time in more arid regions and decreasing in more humid regions. We also quantified hydrologic drought using the standardized streamflow index (SSI) and compared time it took for reservoir storage (expressed as anomalies in fraction filled) and SSI to recover. As would be expected, we see longer drought periods and more prolonged negative reservoir storage anomalies in the more arid basins. That said, nearly all regions have we show that the reservoir storage takes longer to recover from drought that the streamflow.
... Apart from mismanagement, some reservoirs induce downstream riverbank erosion, causing more severe flood peaks (Mei et al., 2018). In many cases, over-reliance on reservoirs also reduces communities' incentive for adaptive actions, increasing their vulnerability and potential damages caused by socioeconomic droughts (Di Baldassarre et al., 2018). ...
... On the one hand, reservoir operation can attenuate flood and drought events by smoothing streamflow, with lower flood peaks and higher baseflows (e.g., Lee et al., 2017;Wu et al., 2018;Gai et al., 2019). On the other hand, hydrological extremes can be intensified by ineffective management of reservoir water, which in some cases had greater influence than climate change (e.g., Graf, 2006;Mittal et al., 2016;He et al., 2017;Di Baldassarre et al., 2018). Since SEA has an increasing number of dammed reservoirs while being highly exposed to hydrological hazards (Trenberth et al., 2014;Arnell & Gosling, 2016), there is an urgent need to evaluate effects of reservoir operation on streamflow in specific contexts of this region. ...
... Affordability ratios are a commonly used metric for quantifying water affordability in which water droughts often increase water rates 32 , but household affordability is typically not included in these planning models. In the area of sociohydrology, recent work has focused on developing a process-based understanding of coupled human water systems with the aim of identifying critical components, nonlinear interactions and feedback [33][34][35][36] . Recent studies have investigated the connections between human behaviour and flood 34,37 , agricultural irrigation 36,38 and drought 39 . ...
... In the area of sociohydrology, recent work has focused on developing a process-based understanding of coupled human water systems with the aim of identifying critical components, nonlinear interactions and feedback [33][34][35][36] . Recent studies have investigated the connections between human behaviour and flood 34,37 , agricultural irrigation 36,38 and drought 39 . In both decision support modelling and socio-hydrology, existing approaches have focused on aggregate indicators at the city, watershed or regional scale, aligned with the scale of decision-making rather than impact, where household-level affordability is typically addressed separately from water-supply decisions via rate setting and low-income assistance programmes 40 . ...
In water-stressed regions, droughts pose a critical challenge to urban water security for low-income households. Droughts reduce water availability, forcing water providers to invest in additional supplies or enact expensive, short-term emergency measures. These costs are frequently passed on to households through increased rates and surcharges, driving up water bills for low-income households and altering patterns of water consumption. Here we have developed a socio-hydrological modelling approach that integrates hydrology, water infrastructure, utility decision-making and household behaviour to understand the impacts of droughts on household water affordability. We present here an application based on Santa Cruz, California and show that many drought resilience strategies raise water bills for low-income households and lower them for high-income households. We also found that low-income households are most vulnerable to both changing drought characteristics and infrastructure lock-in. Unaffordable water prices pose a threat to human health and well-being. A socio-hydrological modelling approach that integrates hydrology, water infrastructure, utility decision-making and household behaviour can be used to understand the impacts of droughts on household water affordability
... Water storage for irrigation can be provided through water harvesting with small dams (32), managed aquifer recharge (33), and better management of soil moisture (34). Yet, existing irrigation systems often rely on gray infrastructure in the form of dammed reservoirs (30,31) to provide water storage (30,(35)(36)(37). ...
... In basins with existing irrigation storage, maintenance of catchments and reservoirs, and thus reducing the amount of storage lost to sedimentation, is crucial to ensure that existing infrastructure can contribute to future storage-fed irrigation in the long-term (56). In the past more storage often led to inefficient water use and increased hydrologic extremes (57,58), rather than fueling an increase in crop productivity (35,36), which highlights that any increase in irrigation, and associated storage, needs to be embedded in demand management to avoid rebound effects (59). For example, demand for storage depends on biophysical water demands of crops but also on how much of the releases from storage are available to crops on the field. ...
Providing affordable and nutritious food to a growing and increasingly affluent global population requires multifaceted approaches to target supply and demand aspects. On the supply side, expanding irrigation is key to increase future food production, yet associated needs for storing water and implications of providing that water storage, remain unknown. Here, we quantify biophysical potentials for storage-fed sustainable irrigation—irrigation that neither depletes freshwater resources nor expands croplands but requires water to be stored before use—and study implications for food security and infrastructure. We find that water storage is crucial for future food systems because 460 km3/yr of sustainable blue water, enough to grow food for 1.15 billion people, can only be used for irrigation after storage. Even if all identified future dams were to contribute water to irrigation, water stored in dammed reservoirs could only supply 209 ± 50 km3/yr to irrigation and grow food for 631 ± 145 million people. In the face of this gap and the major socioecologic externalities from future dams, our results highlight limits of gray infrastructure for future irrigation and urge to increase irrigation efficiency, change to less water-intensive cropping systems, and deploy alternative storage solutions at scale.
... Water storage for irrigation can be provided through water harvesting with small dams (32), managed aquifer recharge (33), and better management of soil moisture (34). Yet, existing irrigation systems often rely on gray infrastructure in the form of dammed reservoirs (30,31) to provide water storage (30,(35)(36)(37). ...
... In the past more storage often led to inefficient water use and increased hydrologic extremes (57,58), rather than fueling an increase in crop productivity (35,36), which highlights that any increase in irrigation, and associated storage, needs to be embedded in demand management to avoid rebound effects (59). For example, demand for storage depends on biophysical water demands of crops but also on how much of the releases from storage are available to crops on the field. ...
Providing affordable and nutritious food to a growing and increasingly affluent global population requires multifaceted approaches to target supply and demand aspects. On the supply side, expanding irrigation is key to increase future food production, yet associated needs for storing water and implications of providing that water storage, remain unknown. Here, we quantify biophysical potentials for storage-fed sustainable irrigation—irrigation that neither depletes freshwater resources nor expands croplands but requires water to be stored before use—and study implications for food security and infrastructure. We find that water storage is crucial for future food systems because 460 km ³ /yr of sustainable blue water, enough to grow food for 1.15 billion people, can only be used for irrigation after storage. Even if all identified future dams were to contribute water to irrigation, water stored in dammed reservoirs could only supply 209 ± 50 km ³ /yr to irrigation and grow food for 631 ± 145 million people. In the face of this gap and the major socioecologic externalities from future dams, our results highlight limits of gray infrastructure for future irrigation and urge to increase irrigation efficiency, change to less water-intensive cropping systems, and deploy alternative storage solutions at scale.
... Hess et al. (Eekhout et al., 2018) highlighted the mechanisms by which increased precipitations can threaten water security supporting their findings through a hydrological analysis. While a lack of datasets and analytical tools may prevent a full investigation of this (Di Baldassarre et al., 2018), detrimental feedback can be identified that involve relying on reservoirs to mitigate water shortages. Two of these are. ...
... • the spiralling up of the supply-demand cycle, where increasing water supply enables the development of economical activities and urbanisation relying on freshwater supplies (Kallis, 2010) and • the reservoir effect (Di Baldassarre et al., 2018), by which the perceived water security given by the presence of water reservoirs disincentives parallel adaptation actions. This means that the reservoir needed for everyday life as opposed to a device meant for mitigating exceptional droughts and/or provide buffer for floods. ...
The cyber-physical nature of engineering systems requires the smooth integration of decision making across soft and hard infrastructure. This need is common to any systems where decision making considers multiple complex systems such as the climate, the natural and built environment, and the dynamics of large organisations. As an example, in the Anthropocene, acute droughts and floods cannot only be imputed to more extreme variations of the climate patterns, but also to the alteration of the habitable environment and of the resources that support it, hence to their governance and management. In this discussion paper we present arguments about the extent to which the natural environment is modified to support urbanisation. We expose the cyber-physical nature of large infrastructure systems taking as an example the events of the 2011 Brisbane flood and the operations of the damming system of the river Brisbane. Using literature resources and data, we show how flood defence devices had to provide for a population of almost 2 million people, while being engineered when the population was less than one million, with increase in water withdrawal mainly due to residential utilities. We show how the cyber-physical aspects of the problem materialised in moth-long delays in the governance and management structure and made the flood event transcend the boundary of a purely climatic or engineering incident. Looking beyond the Brisbane example, our conclusions point at overcoming the discontinuity between operation, management and political layers when operating on cyber-physical systems such as freshwater networks.
... On the other hand, most of the time, the building of small reservoirs occurs without technical supervision, lacking hydrological studies and disregarding the potential impacts on the availability of water for downstream regions [1,6]. Usually, small reservoirs represent risks to the population downstream in the rainy season, since many of these reservoirs do not have well-sized structures for flood control, with the risk of a dam break during periods of more intense floods. ...
... Recent studies have been carried out to assess the cumulative impact of small reservoirs, such as the increase in evaporation losses [13,14] and the decrease in runoff generated in the catchment [1,4,[15][16][17][18]. In addition, other studies have investigated the effect of small reservoirs on sediment retention dynamics [19][20][21], the reduction of energy demand for water pumping [22], and the evolution and intensification of drought events [3,6,23]. ...
Small reservoirs play an important role in providing water to rural communities. Increased construction of small reservoirs to mitigate the effects of droughts leads to a High-density Reservoirs Network (HdRN) of small reservoirs, which can potentially modify the streamflows both in dry and wet periods. However, there is a lack of understanding of the interannual behavior of flow retention and the impact of future increases in the number of small reservoirs, mainly for HdRN in dryland catchments. This research aims to determine the possible impact of the increase in the number of small reservoirs on dry hydrological networks, evaluating the annual flows generated at the outlet of a dryland watershed for scenarios with different densities of small reservoirs (number of reservoirs per area). The study area was the Conceição river catchment (3347 km²) in the semiarid of Brazil. The hydrological model of the study area was developed in SWAT. The model obtained appropriate results for daily streamflows, with values of 0.63, 0.81, and 0.53% for NSE, KGE, and PBIAS, respectively. The current density of small reservoirs in the region was estimated at 0.068 reservoirs per square kilometer (res/km²). Eight expansion scenarios were defined for densities between 0.1 res/km² and 3.0 res/km². The results showed that the influence of the HdRN on runoff reduction mostly occurs for a probability of exceedance between 1% and 10% of month flows and is very small for months with very high peaks of flow. The reduction in the outlet flow due to the increase in the number of small reservoirs was stronger during dry years (up to 30%) than during wet years (up to 8%), and it tended to increase in years with a consecutive lack of rain (from about 7% in the first year to about 20% in the last year and in the worst scenario), which may intensify the period of extended droughts. This research provides insights about the impact of the increase in the number of small reservoirs on the interannual variability of flow retention, and the understanding of the influence of small reservoirs on runoff reduction may help water resources agencies better prepare for hydrologic extremes (droughts and floods).
... The aforementioned studies have investigated the feasibility of reservoir expansion in different regions of the United States [12,17]. However, there is a lack of nationwide studies to provide insight regarding the national scale picture of reservoir expansion potential [18]. ...
... First, although reservoirs aimed to maintain a balance between water supply and water demand and increase the reliability of water supply systems, there is ongoing discussion that expanding and building the reservoirs may increase long-term water use and lead to more severe drought conditions. For instance, Baldassarre et al., (2018) [17] found that increasing reservoir storage over the last decades has affected downstream flows and highlighted that reservoir expansion can worsen the water shortage conditions if other aspects are not given enough attention. ...
Reservoir expansion is commonly considered an adaptation strategy to attenuate water shortage conditions. In many locations in the United States, there are ongoing discussions about the effectiveness and feasibility of reservoir expansion with regard to the growing drought conditions and a consequent significant decrease in surface water. This study investigates if the expansion of the existing Unites States reservoirs should be still considered an effective and adequate management solution to cope with water shortages. To this end, we have defined three reservoir expansion metrics to assess the efficiency, feasibility, and usefulness of increasing the storage capacity of 304 reservoirs across the conterminous United States (CONUS). The efficiency metric is defined as the ratio of reservoir average storage to maximum active storage. The feasibility metric is defined as the ratio of reservoir average annual inflow to maximum active storage and the usefulness metric is described as the ratio of the reservoir average annual excess inflow (average annual inflow–maximum active storage) to the average intensity of water shortages. The finding indicates that most reservoirs in Colorado and Utah currently have high or very high efficiency metrics meaning that these reservoirs are, on average, more than half full while most reservoirs in Texas have low or medium efficiency metrics indicating that these reservoirs are, on average, less than half full. Additionally, the feasibility metrics indicate that reservoir expansion in most western and southern states may not be fruitful because the average annual inflow to reservoirs is less than their maximum active storage over the historical period. Nevertheless, the usefulness metrics show that reservoir expansion can be a useful adaptation strategy to mitigate or attenuate water shortages for some reservoirs in California and Colorado while it cannot considerably decrease the intensity of water shortages in Texas. Findings from this study highlight the utility of the assessment of reservoir expansion at a regional scale considering both available freshwater as an input to reservoirs and the potential water shortage conditions as the main trigger.
... "Lessons from the past" or variations thereupon (e.g. Di Baldassarre et al., 2021Baldassarre et al., , 2018Holt, 2017;Kaptijn, 2017;Koutsoyiannis et al., 2008) is becoming more popular as water management experiences from the past can inform nowadays. In another word, understanding how water management efforts in the past were able to remain sustainable in the face of changes (e.g., climate change and increased demographic pressure), or why they failed to do so, can bring valuable information for water stakeholders and managers nowadays. ...
... How reservoir systems can be adapted to future changes requires not only a far-sighted view of possible changes in water supply and water demand but also a thorough understanding of the socio-hydrology relationship (Di Baldassarre et al., 2018;Kellner, 2021;Sivapalan and Blöschl, 2015). Adapting to global change must reject stationary practice that hinges on historical conditions, and embrace non-stationary planning and management. ...
Understanding the vulnerability of water management under global change is the premise for designing adaptation actions. A comprehensive assessment of current water management vulnerability to future changes hinges on new tools that are able to represent human impact on water resources and innovative frameworks that are able to generate new insights to inform adaptation designing. Therefore, this dissertation sets out to (1) develop and improve models to represent water resources, water demand, and water management in an integrated hydrological modelling framework; (2) apply a "scenario-neutral" bottom-up framework and a "scenario-led" top-down framework to identify and investigate plausible vulnerability and impact under global change. These developments and applications are demonstrated by taking the Neste water system in French Pyrenees as a case study.
... While the availability of dam sites is limited in post-industrial countries, existing dams can be enhanced; projects such as increasing dam height or installing pumped storage power stations are being implemented (Pittock, 2010;Pittock and Hartmann, 2011;Ehsani et al., 2017). Recent papers in the environmental sciences, however, have demonstrated that dams are not always an advantageous option in times of climate change in that reliance on reservoirs can worsen water and energy shortages (Di Baldassarre et al., 2018) and the impact of climate change on impounded rivers can be greater than on free-flowing ones (Palmer et al., 2008). A second discussion relates to the reoperation of dam reservoirs. ...
In the context of climate change, hydropower dams and reservoirs are being promoted as mitigation and adaptation tools. The reoperation of dam reservoirs is also being considered, particularly in countries where dams are currently undergoing relicensing procedures. In Switzerland, a country that is often considered to be the water tower of Europe, concerns are being expressed about the future of water resources. These concerns are reinforced by the fact that the country's water system is heavily impounded by hydropower dams whose licenses are about to expire. Discussions are emerging on future hydropower production and on multipurpose projects in the context of hydropower dam reservoir reoperation. Building on previous studies in political ecologies of water and on studies of environmental and sociotechnical imaginaries, and relying on policy documents and interviews with water and energy stakeholders, we investigate the way in which multiple use of hydropower dam reservoirs is envisioned in Switzerland and in the Valais canton. At the moment in Switzerland, the idea of multiple use of dam reservoirs is far from being recognised as a water and energy management paradigm; it is, however, strongly associated with climate-related socio-environmental changes in the water sector and with changes in ideas about water, dam futures, energy and the social structure. We highlight the coexistence of three different environmental and sociotechnical imaginaries and connect these imaginaries with ongoing and future hydrosocial change.
... In natural sciences, recent research has contributed to the understanding of long-term unintended consequences of large grey infrastructure in societies such as reservoirs, drainage networks and levees. The 'reservoir effect' emerges when societies over-rely on large water transfers for their water supply, an unintended consequence of the long-term dependency of societies to reservoirs and their increasing vulnerability to hydro-climatic events (Di Baldassarre et al. 2018). The 'levee effect' emerges when levees are built to protect societies from flooding, but in turn diminishes social memory over larger periods of time by giving a sense of unfounded sense of security that can backfire with an extreme hydro-climatic event (Di Baldassarre et al. 2013). ...
This chapter provides the context of water security for ecosystem-based approaches, notably nature-based solutions (NBS) operationalized in natural assurance schemes (NAS). The huge potential and value of nature-based solutions to both mitigate the effect of water while providing large and important co-benefits is addressed in this book and for this a deeper understanding is needed on how this contributes to water security and how barriers to implementation of NBS and NAS can be overcome. Firstly, relevant concepts and approaches of water security are introduced and reviewed; secondly, the assurance and insurance value is elaborated upon as distinct properties of ecosystem-based approaches; thirdly, the concepts of readiness levels for technology and knowledge, socio-institutionality and investment are introduced to address barriers for the operationalization of the value of ecosystem-based schemes to develop and harvest the full potential of climate resilient investments while addressing EU policies, including the Green Deal, Climate Adaptation Strategy and Strategy for Biodiversity. Finally, based on this chapter, overarching questions are posed which are addressed and discussed in the course of this book.
... Water is an essential resource for human beings and performs important functions in ecosystems (Huggins et al., 2022) and sustainable development (Sheffield et al., 2018). The current regional allocation of water resources is extremely unbalanced (Yao et al., 2019), and many regions are experiencing water shortages (Di Baldassarre et al., 2018), while water resources in many places are too concentrated (Dile et al., 2018). The uneven spatial and temporal distribution of water resources is the basis for the occurrence of droughts and floods (He et al., 2020). ...
Quantifying uncertainty in runoff changes has profound implications for future runoff investigations and will support global climate model improvement. We analyze the runoff changes from model outputs of the 5th and 6th Coupled Model Intercomparison Projects (CMIP5 and CMIP6) and decompose the uncertainty of projected runoff changes into three main sources: internal variability, model uncertainty, and scenario uncertainty. The results indicate that 73% and 72% of the global land area, respectively, shows an increase in runoff for CMIP5 and CMIP6 under the high‐emissions scenarios in the long term (2070–2099) relative to 1970–1999, and runoff across all global land increases by 10.8% under the RCP8.5 scenario and 16.1% under SSP5–8.5 during 2070–2099 relative to 1970–1999. Regions with increasing runoff are mainly in Southeast Asia, eastern Africa, the Qinghai‐Tibet Plateau and the high latitudes of the Northern Hemisphere. Model agreement during 2070–2099 for runoff changes under the high‐emissions scenarios is greater than under the low‐emissions scenarios. For uncertainty of relative changes in runoff (RRC) in CMIP6, the contribution from internal variability gradually decreases over time (from 49.2% to 2.0%) while the contribution from scenario uncertainty increases (from 0.6% to 30.0%); this result is similar in CMIP5. Spatially, model uncertainty in RRC has been a major source of uncertainty for CMIP5 and CMIP6, accounting for more than 60% of total uncertainty in most regions. The results of this study help us to better understand the uncertainty in runoff changes and also provide a theoretical basis for developing mitigation measures for future changes.
... 54 By legitimising a doing what I want attitude, privileged emotions reinforce elites' neoliberal merits thereby producing hydrosocial reconfigurations that are both unjust and unsustainable. Specifically, the increasing use of private boreholes risks triggering what ecological economists and sociohydrologists define as the supply-demand cycle i.e. an unforeseen increase in water demand as a result of the expansion or construction of additional water infrastructure (Di Baldassarre et al., 2018;Kallis, 2010). In this case, the development of private boreholes by elites could produce a supply-demand cycle which in the longerterm, would deplete the local aquifers and in turn, reduce the future water available for the entire population. ...
Political ecology has already engaged with emotions in order to reveal the intimate, unconscious and unexplored power dynamics which characterise patterns of water use and control. Similar explorations have mostly focused on the emotional struggles of structurally disadvantaged people rather than on the emotions of those with privilege: the elite. This oversight becomes problematic when it conceals disproportionate shares of power and the implications that such power has on the sustainable use and just distribution of water resources. The 2018 water crisis which affected Cape Town's metropolitan area constitutes the empirical context of this paper, which sets out to address the aforementioned research gap. Focusing on the elite's emotional responses to Cape Town's drought and subsequent water crisis, this paper seeks to advance political ecology's understanding of urban water crises by retracing the emotional geography of Cape Town's most privileged urban dwellers. In particular, this work leverages the concept of subjectivity to explain the way emotions are constructed and come to materially and discursively reproduce historical power dynamics. These findings reveal that fear, anger, and a sense of pride felt by wealthier Capetonians results from and perpetuates the privileged conditions of those elite. Rooted in colonial and apartheid past, Capetonians' privileged emotions end up perpetuating the main causes of the water crisis and eventually excluding the most disadvantaged inhabitants from future use and control of water resources. Ultimately, by connecting with privileged emotions, it is possible to challenge certain sub-jectivities and create space for more just and sustainable urban-water imaginaries.
... In both the Northern and the Southern hemispheres, metropolitan areas experience extreme droughts and unsustainable levels of water consumption 6 (Fig. 1). In the face of fluctuating supplies, meeting the growing urban water demands and finding a sustainable balance among the city, its rural hinterland and environmental flow requirements is becoming increasingly challenging 4,7,8 . ...
Over the past two decades, more than 80 metropolitan cities across the world have faced severe water shortages due to droughts and unsustainable water use. Future projections are even more alarming, since urban water crises are expected to escalate and most heavily affect those who are socially, economically and politically disadvantaged. Here we show how social inequalities across different groups or individuals play a major role in the production and manifestation of such crises. Specifically, due to stark socioeconomic inequalities, urban elites are able to overconsume water while excluding less-privileged populations from basic access. Through an interdisciplinary approach, we model the uneven domestic water use across urban spaces and estimate water consumption trends for different social groups. The highly unequal metropolitan area of Cape Town serves as a case in point to illustrate how unsustainable water use by the elite can exacerbate urban water crises at least as much as climate change or population growth.
... Os reservatórios também podem ter impactos negativos na disponibilidade de água (Di Baldassarre et al., 2018). Enquanto os reservatórios aumentam inicialmente a oferta de água, isso também pode resultar no aumento da demanda, causando a escassez hídrica (Van Loon and Lanen, 2013;Van Loon et al., 2016). ...
... These considerations, which lead us to more elaborate phases of the SD model, are what explain the counter-intuitive nature of the system in the face of certain solutions that try to alleviate water scarcity. Thus, for example, improving the efficiency of irrigation systems often leads to higher water consumption [30,31]. ...
... Os reservatórios também podem ter impactos negativos na disponibilidade de água (Di Baldassarre et al., 2018). Enquanto os reservatórios aumentam inicialmente a oferta de água, isso também pode resultar no aumento da demanda, causando a escassez hídrica (Van Loon and Lanen, 2013;Van Loon et al., 2016). ...
... While technology can increase the efficiency of freshwater exploitation, for example, through more efficient irrigation practices, such interventions might negatively affect the existing water scarcity issue [13]. In addition, drought vulnerability can be increased due to intervention to raise water resources levels, such as dams [14]. ...
Date production and consumption is mostly diffused in Middle East and Northern African countries. Date production is linked to the land and water footprint in countries where agricultural land and freshwater are scarce. We estimate the global land, green water, blue water, and water scarcity footprint at the country scale from a production perspective. We show that production trends are increasingly driven by foreign demand. By tracking the international trade dynamics of dates, we map the shift of environmental footprint from the producing to the consuming countries. We find that dates production and consumption are not yet decoupled from the associated environmental burden. Global dates consumption accounted for 1.4 million hectares of agricultural land, 5.8 Gm3 of green water, 7.5 Gm3 of blue water, and the related impact on water scarcity reached 358 Gm3 world equivalent in 2019. The primacy of the economic driver is revealed, indicating that in the case of dates, the environmental sustainability aspects are currently overlooked for the sake of the economic benefit. The time-series analysis provides informative results to support policymakers in the design of mitigation strategies that can help the achievement of the SDGs.
... However, despite their benefits, reservoirs remain controversial due to their potentially negative impacts by altering the natural flow regime Mittal et al., 2016). Furthermore, hydrological extremes can be intensified by ineffective management of reservoir water, which can sometimes have an impact greater than climate change (Di Baldassarre et al., 2018;Vu et al., 2017). Therefore, there is a need to evaluate the effects of reservoir operations on streamflow in specific multi-basin catchments. ...
Hydraulic infrastructures, such as reservoirs and water diversion channels, cause altered streamflow worldwide. Therefore, this study aimed to assess the coupled impacts of reservoir operations and water transfer on downstream streamflow over 42 years (1979–2020) for a tropical river in Vietnam, the Vu Gia Thu Bon (VGTB). We also quantified variations in the multi-sub-basin contributions to the water budget associated with hydraulic structure development. Therefore, a semi-distributed hydrological model, SWAT (Soil and Water Assessment Tool), was developed for the entire VGTB basin considering two plausible scenarios: with a dam and without a dam. In this study, reservoirs substantially affected the streamflow during the 2011–2020 period when 12 cascading hydropower dams were constructed in the Vu Gia sub-basins. The cascading reservoirs across the Vu Gia River reduced the annual average streamflow by 28.1% during this period, whereas their influence was augmented by 13.9% at reaches further downstream. In contrast, the local reservoir and flow diversions created on the Thu Bon River resulted in a 6.5% increase in streamflow. The upstream reservoir operation significantly increased streamflow at the midstream stations by 27.8% compared to the no-dam period. The streamflow decreased in the dry season by 5.6% in the Vu Gia sub-basins and increased by 61.7% in the Thu Bon sub-basins. However, the impacts decreased in the wet season by 41.3% due to the operation of reservoirs, in which Dak Mi 4 had the most significant influence. It was found that the water diverted to the Thu Bon River was governed and reduced by the cascading hydropower dams. Therefore, the operation of 11 reservoirs has partially compensated for the lost water in the Vu Gia sub-basins, to which the Dak Mi 4 plant has transferred 19.7 m3/s (14%). Our findings classify the impact of cascading dams and diversion structures and their interaction with climate change.
... For example, filling the Grand Ethiopian Renaissance Dam (GERD, 74 km 3 capacity) could greatly reduce reservoir levels in the High Aswan Dam reservoir downstream, and management of both reservoirs will be required to address multiyear droughts 148 . Based on the Jevons paradox, as with respect to irrigation efficiency, increasing water supplies can increase demands and make systems more vulnerable to shortages 149 . ...
Water is a critical resource, but ensuring its availability faces challenges from climate extremes and human intervention. In this Review, we evaluate the current and historical evolution of water resources, considering surface water and groundwater as a single, interconnected resource. Total water storage trends have varied across regions over the past century. Satellite data from the Gravity Recovery and Climate Experiment (GRACE) show declining, stable and rising trends in total water storage over the past two decades in various regions globally. Groundwater monitoring provides longer-term context over the past century, showing rising water storage in northwest India, central Pakistan and the northwest United States, and declining water storage in the US High Plains and Central Valley. Climate variability causes some changes in water storage, but human intervention, particularly irrigation, is a major driver. Water-resource resilience can be increased by diversifying management strategies. These approaches include green solutions, such as forest and wetland preservation, and grey solutions, such as increasing supplies (desalination, wastewater reuse), enhancing storage in surface reservoirs and depleted aquifers, and transporting water. A diverse portfolio of these solutions, in tandem with managing groundwater and surface water as a single resource, can address human and ecosystem needs while building a resilient water system.
... For example, filling the Grand Ethiopian Renaissance Dam (GERD, 74 km 3 capacity) could greatly reduce reservoir levels in the High Aswan Dam reservoir downstream, and management of both reservoirs will be required to address multiyear droughts 148 . Based on the Jevons paradox, as with respect to irrigation efficiency, increasing water supplies can increase demands and make systems more vulnerable to shortages 149 . ...
Water is a critical resource, but ensuring its availability faces challenges from climate extremes and human intervention. In this Review, we evaluate the current and historical evolution of water resources, considering surface water and groundwater as a single, interconnected resource. Total water storage trends have varied across regions over the past century. Satellite data from the Gravity Recovery and Climate Experiment (GRACE) show declining, stable and rising trends in total water storage over the past two decades in various regions globally. Groundwater monitoring provides longer-term context over the past century, showing rising water storage in northwest India, central Pakistan and the northwest United States, and declining water storage in the US High Plains and Central Valley. Climate variability causes some changes in water storage, but human intervention, particularly irrigation, is a major driver. Water-resource resilience can be increased by diversifying management strategies. These approaches include green solutions, such as forest and wetland preservation, and grey solutions, such as increasing supplies (desalination, wastewater reuse), enhancing storage in surface reservoirs and depleted aquifers, and transporting water. A diverse portfolio of these solutions, in tandem with managing groundwater and surface water as a single resource, can address human and ecosystem needs while building a resilient water system.
... This shows the existence of supply-demand feedbacks where increased supply (from RWH or another supply measure) leads to more demand, offsetting the benefits from the increased supply (Glendenning et al., 2012;Scott et al., 2014;Di Baldassarre et al., 2018). The increase in demand, associated with increased irrigation and cropping intensity may lead to greater shocks in dry years when water availability remains low and CDs are less effective. ...
Rainwater harvesting systems (RWHs) are implemented globally to bridge the frequent water supply-demand gaps. This study explores, through farmer household surveys ( n = 492), how farmers perceived the benefits of RWHs, the equitability of benefits, and the role of contextual and psychological factors towards the behaviour of maintaining such systems. The study is carried out in a semi-arid catchment in the Indian state of Gujarat where RWHs, in the form of Check dams (CDs), have been implemented extensively. Results show that the benefits of CDs are perceived in good rainfall years through enhanced availability of water for expanding crops and irrigated areas. Farmers reported limited benefits of CDs in dry years. This is because of limited runoff and no carryover of stored groundwater, due to underlying shallow hard rock aquifer with little primary porosity, from wet years to dry years. Overall, ∼ 40%–50% of sampled farmers reported no benefits from CDs and the benefits decreased with distance. This reflects a spatially inequitable distribution of benefits skewed towards the farmers nearest to the CDs. The sustainability of CDs is a challenge with already ∼40% of CDs reportedly not working and 72.8% of farmers reported doing no maintenance activity. This is because 91.2% of farmers reported playing no role in its construction. The results show contextual (participation during construction, economic indicators) and sociopsychological factors (attention to CD condition, maintenance effort) significantly affect the behaviour towards maintaining the CDs. This highlights the need to complement RWHs with wider drought management and water demand management interventions to achieve drought resilience, and adherence to project exit protocols to secure the sustainability of investments.
... Approximately, one-third of the world's population now relies on groundwater resources to meet their drinking water needs (Jain and Vaid 2018). Groundwater pollution as a result of natural environmental changes and human activity such as agricultural and industrial actions is continuously reducing the quality of groundwater, resulting in water contamination in many areas of the world (Adimalla and Qian 2021;Di Baldassarre et al. 2018). The situation in India is even more critical as the country ranks second in the world in terms of population and it is difficult to meet the drinking water needs of such a large population. ...
The quality of groundwater in the Jaunpur district of Uttar Pradesh is poorly studied despite the fact that it is the only supply of water for both drinking and irrigation and people use it without any pre-treatment. The evaluation of groundwater quality and suitability for drinking and irrigation is presented in this study. Groundwater samples were collected and analysed by standard neutralisation and atomic emission spectrophotometry for major anions (HCO3⁻, SO4²⁻, Cl⁻, F⁻, NO3⁻), cations (Ca²⁺, Mg²⁺, Na⁺, K⁺), and heavy metals (Cd, Mn, Zn, Cu, and Pb). The geographic information system (GIS) and statistical inferences were utilised for the spatial mapping of the groundwater’s parameters. The potential water abstraction (i.e. taking water from sources such as rivers, streams, canals, and underground) for irrigation was assessed using the sodium absorption ratio (SAR), permeability index (PI), residual sodium carbonate (RSC), and Na percentage. According to the findings, the majority of the samples had higher EC, TDS, and TH levels, indicating that they should be avoided for drinking and irrigation. The positive correlation coefficient between chemical variability shows that the water chemistry of the studied region is influenced by geochemical and biological causes. According to the USSL (United States Salinity Laboratory) diagram, most of the samples fall under the C2-S1 and C3-S1 moderate to high salt categories. Some groundwater samples were classified as C4-S3 class which is unfit for irrigation and drinking. This study suggests that the groundwater in the study area is unfit for drinking without treatment. However, the majority of the samples were suitable for irrigation.
... This issue is also further complicated by the predicted increase in urban population, which is estimated to reach up to 6.7 billion by 2050, with the consequent increase in both wastewater produced and freshwater water resources needed (He et al., 2021;United Nations/DESA, 2019). Since other freshwater sources such as desalinization processes or rainfall collection face important technical challenges (Ayaz et al., 2022;He et al., 2021;Oki and Quiocho, 2020), this will create a negative feedback loop that perpetuates the cycle of resource depletion (Di Baldassarre et al., 2018;Greve et al., 2018). Thus, it is fundamental to develop new technologies for managing, treating, and reusing water and wastewater (Fan et al., 2019). ...
Cavitation-based technologies have emerged as a sustainable and effective way to treat natural waters and wastewater, considering their increasing scarcity due to pollution and climate change. For this reason, this work aimed to conduct a scientometric analysis on the topic of cavitation for water and wastewater treatment during the last 20 years, from 2001 to August 2022. We focused on hydrodynamic and ultrasonic cavitation as the prevalent methods of inducing cavitation. Furthermore, an in-depth study on the main trends regarding the number of publications and citations, keywords co-occurrence and evolution, and countries' publication trends was carried out to investigate the future direction of this research topic. The data was gathered from the Web of Science database and analyzed by the Visualization Of Similarities software. This work focused on: i) publication and citation trends, ii) scientific categories, iii) countries' contribution to the topic of cavitation, iv) prominent journals, v) keyword co-occurrence and cluster analysis, and vi) keyword evolution analysis. Results showed a significant increase in publications during the past 5 years. The scientific categories with the highest number of publications were “environmental sciences” and “environmental engineering,” with a combined share of 19.4 % of publications. Keywords evolution analysis showed that limited focus was given to topics related to “energy” and “energy efficiency” in the field of cavitation, but with the rising importance of each process's sustainability, the attention given to these concepts will increase in the future.
Future directions for the topic of cavitation-related water and wastewater treatments will shift towards more environmentally friendly applications of hydrodynamic and ultrasonic cavitation as well as towards more green and sustainable approaches to address the increasing water pollution problems and shortage. Moreover, it will include other uses besides water treatment such as manufacturing nanomaterials food production and medicine.
... We then identify basins exposed to snowmelt risks as those snow-dependent ones which are simultaneously subjected to decreases in snowmelt consumption ratio (share of surface irrigation demand met by snowmelt runoff) and increases in alternative water demand ratio (share of irrigation surface-water demand met by alternative water supply) under the 2 °C and 4 °C warming scenario, respectively ( Supplementary Fig. 10), as defined in an earlier study 16 . Alternative water sources can come from interbasin water transfer, more groundwater pumping or expanding reservoir storage; however, such strategies may have unintended side effects resulting from expanding water storage and reservoir reliance 66,67 , as well as unsustainable groundwater use 68 . ...
Climate change is altering the timing and magnitude of snowmelt, which may either directly or indirectly via global trade affect agriculture and livelihoods dependent on snowmelt. Here, we integrate subannual irrigation and snowmelt dynamics and a model of international trade to assess the global redistribution of snowmelt dependencies and risks under climate change. We estimate that 16% of snowmelt used for irrigation is for agricultural products traded globally, of which over 70% is from five countries. Globally, we observe a prodigious snowmelt dependence and risk diffusion, with particularly evident importing of products at risk in western Europe. In Germany and the UK, local fraction of surface-water-irrigated agriculture supply exposed to snowmelt risks could increase from negligible to 16% and 10%, respectively, under a 2 °C warming. Our results reveal the trade-exposure of agricultural supplies, highlighting regions and crops whose consumption may be vulnerable to changing snowmelt even if their domestic production is not.
... PDQ exposure) through management actions, such as stormwater capture and irrigation. Irrigation, nonetheless, may not be a sustainable solution in many places where water is increasingly scarce (Di Baldassarre et al., 2018;Hoekstra and Mekonnen, 2012). ...
Urban tree inventories are useful tools to assess the environmental and socio-economic services provided by urban forests. These inventories enable the evaluation of the climate change risk to urban forests, and governments rely on such inventories for urban planning and management. Here, we assessed the future climate risk of Australia and the state of urban tree inventories across 116 local government areas (LGAs), representing 21% of the country’s LGAs and encompassing 55% of the national human population. We evaluated projected changes in temperature and precipitation by 2050 for each LGA and conducted a survey to obtain information on the extent and types of data available in existing urban tree inventories. Additionally, we compiled demographic, socio-economic, and geographical data for all LGAs to explore correlates with tree inventory status. Temperature increases in 2050 were predicted in all LGAs, with higher latitude and smaller LGAs identified to undergo greater increases in temperature compared to larger and lower latitude LGAs. Decreases in seasonal precipitation were predicted for 97 LGAs. Seventy-six (66%) of surveyed LGAs had urban tree inventories, which most commonly included trees along streets and in parks. Sixty-one LGAs record information on tree mortality, while 31 LGAs dynamically update their inventories. The presence of an inventory and the area it covered were positively associated with human population density. More than 30 years ago, in 1988, John Gray wrote that “insufficient statistics were available in Australia to provide an accurate picture of the urban forest estate”. Our research shows there has not been a significant advance in the adoption and use of urban forest inventories over the past three decades. Long-term, dynamically updated inventories are crucial for urban forest management to inform planting choices to support sustainable and resilient cities.
... Human beings are facing the serious issue of freshwater shortage (Baldassarre et al., 2018;Li et al., 2018a;Tang et al., 2020). Most of water resource cannot be directly reached though water covers about 70 % of Earth (Byers et al., 2020;Zhu et al., 2021a). ...
Herein, inspired by desert beetles, we fabricated a multifunctional heterogeneous superwettable coating (MHSC) for water collection and oily wastewater cleanup. The selective modifications of 1-octadecanethiol (ODT) treated CoO and P25 TiO2 nanoparticles (NPs) were prepared, so hydrophobic CoO NPs and superhydrophilic P25 NPs were combined on the MHSC, showing the water contact angle (WCA) of 156.5° and rolling-off angle (RA) of 6.4°. With the aid of waterborne polyurethane (WPU), five kinds of substrates (i.e., glass slide, dish, wood, fabric, sponge) spray-coated by MHSC displayed high-efficiency water collection rates (WCRs) of 18.1 ± 0.7 mg min-1 cm-2. Moreover, MHSC coated fabric manifested robust oil/water separations with separation efficiencies (SEs) > 99.7 % and fluxes ranged from 9.7 to 11.0 L m-2 s-1. Efficient oil sorption from oily water was obtained by MHSC coated sponge with oil absorption capacities (OACs) of 6.5-29.5 g g-1. Further, even dealt with the treatments of mechanical destructions, extreme temperature and UV illumination, the coated materials remained stable performances.
... For example, increases in irrigation efficiency can reduce streamflow and groundwater recharge because run off is reduced as water is increasingly allo cated to evapotranspiration, often eliminating expected increases in total water availability 250 . Similarly, reliance on reservoir storage can create situations of higher demand and over reliance, increasing vulnerability to droughts 251 . ...
Exceptional drought events, known as megadroughts, have occurred on every continent outside Antarctica over the past ~2,000 years, causing major ecological and societal disturbances. In this Review, we discuss shared causes and features of Common Era (Year 1–present) and future megadroughts. Decadal variations in sea surface temperatures are the primary driver of megadroughts, with secondary contributions from radiative forcing and land–atmosphere interactions. Anthropogenic climate change has intensified ongoing megadroughts in south-western North America and across Chile and Argentina. Future megadroughts will be substantially warmer than past events, with this warming driving projected increases in megadrought risk and severity across many regions, including western North America, Central America, Europe and the Mediterranean, extratropical South America, and Australia. However, several knowledge gaps currently undermine confidence in understanding past and future megadroughts. These gaps include a paucity of high-resolution palaeoclimate information over Africa, tropical South America and other regions; incomplete representations of internal variability and land surface processes in climate models; and the undetermined capacity of water-resource management systems to mitigate megadrought impacts. Addressing these deficiencies will be crucial for increasing confidence in projections of future megadrought risk and for resiliency planning. © 2022, This is a U.S. Government work and not under copyright protection in the US; foreign
... Environment pollution and social development have exacerbated the shortage of global water resources and clean water supplies Science of the Total Environment 856 (2023) 159027 (Baldassarre et al., 2018;Kummu et al., 2010;Yang et al., 2015). Reducing the discharge of produced wastewater is an effective method to control water pollution and improves drinking water production efficiency at drinking water treatment plants (DWTPs) (L. ...
Organic matter reacts with chlorine forming disinfection byproducts (DBPs) including trihalomethanes (THMs), haloacetamides (HAMs), haloacetic acids (HAAs), and haloacetonitriles (HANs). Filter backwash water (FBW) is either released back to the environment or recycled to the head of the treatment plant after solids settling and the remaining dissolved organic matter is a significant pool of DBP precursors that are not well understood. We characterized dissolved organic matter in FBW from 10 treatment plants and low molecular weight (MW < 1 kDa) organic matter contributed the most to DBP formation. We demonstrated overall similarity of the molecular composition (e.g., elemental ratios, m/z, DBE) of the 10 samples of FBW by Fourier transform ion cyclotron resonance mass spectrometry. Aromatic and more highly oxidized compounds preferentially reacted with chlorine, forming DBPs. Low MW (<450 Da) aliphatic compounds, and highly unsaturated and phenolic compounds were the primary precursors of THMs, HANs, and HAMs, and the formation potentials (FPs) of these groups of DBPs were correlated with multiple individual molecular formulae. HAA FPs were correlated with low MW, highly unsaturated and phenolic compounds. These advances in the understanding of the molecular composition of DBP precursors in FBW may develop the effective strategies to control DBP formation and limit impacts on the quality of finished water, and can be expanded to understanding DBP precursors in drinking water sources.
... Likewise, the minimal physical assets the poor have are often highly exposed, subjecting them to disaster-driven poverty traps (Borgomeo et al., 2017). There is increasing demand for management solutions to disaster risk, given the potential adverse effects of physical infrastructure and the relatively low capital costs (Di Baldassarre et al., 2018;Kelman, 2013). Early warning systems are one such solution, requiring minimal physical capital investments, and are increasingly popular in disaster-prone areas. ...
Globally, the direct cost of natural disasters stands in the hundreds of billions of USD per year, at a time when water resources are under increasing stress and variability. Much of this burden rests on low- and middle-income countries that, despite their relative lack of wealth, exhibit considerable vulnerability such that losses measurably impact GDP. Within these countries, a growing middle class retains much of its wealth in property that may be increasingly exposed, while the few assets the poor may possess are often highly exposed. Vulnerability to extreme events is thus heterogeneous at both the global and subnational level. Moreover, the distribution and predictability of extreme events is also heterogeneous. Disaster managers and relief organizations are increasingly consulting operational climate information services as a way to mitigate the risks of extreme events, but appropriately targeting vulnerable communities remains a challenge. The advent of forecast-based anticipatory action has added to the suite of opportunities—and complexity—of operationalizing such services given varying prediction skill. Forecasts, including those at the subseasonal-to-seasonal (S2S) scale, may allow disaster managers to shift effort and therefore some risk from post-disaster response to pre-disaster preparedness; however, given the recent emergence of such programs, only a few, specific case studies have been evaluated. We therefore conduct a country-scale analysis pairing S2S forecast skill for monthly and seasonal lead times with flood and drought disaster risk to explore the potential for forecast-based anticipatory action programs broadly. To investigate subnational heterogeneity in risk and predictability, we also evaluate focused outcomes for the Greater Horn of Africa and Peru. Results suggest that forecast skill plays a large part in determining suitability for early action, and that skill itself varies considerably by disaster type, lead time, and location. Moreover, the physical and socioeconomic factors of risk can vary greatly between national and subnational levels, such that finer scale evaluations may considerably improve the effectiveness of early action protocols. By considering vulnerability at multiple spatial scales and forecast skill at multiple temporal scales, this analysis provides a first identification of promising locations for anticipatory action protocol development.
... Management actions, such as irrigation or stormwater capture, can aid in mitigating the effects of low precipitation by providing supplemental water during periods of severe climate stress 35 evapotranspiration (local cooling effect), which will be crucial to mitigate heatwaves in cities 36 . However, it may become increasingly difficult to mitigate the adverse effects of climate change through management actions to offset soil water deficits, particularly under limited urban water supply and in places where water is increasingly scarce 37,38 . These types of costly management actions may explain why so many tree species are currently present in cities with climates that already exceed their current safety margins at the dry margin for precipitation. ...
Climate change threatens the health and survival of urban trees and the various benefits they deliver to urban inhabitants. Here, we show that 56% and 65% of species in 164 cities across 78 countries are currently exceeding temperature and precipitation conditions experienced in their geographic range, respectively. We assessed 3,129 tree and shrub species, using three metrics related to climate vulnerability: exposure, safety margin and risk. By 2050 under Representative Concentration Pathway 6.0, 2,387 (76%) and 2,220 (70%) species will be at risk from projected changes in mean annual temperature and annual precipitation, respectively. Risk is predicted to be greatest in cities at low latitudes—such as New Delhi and Singapore—where all urban tree species are vulnerable to climate change. These findings aid the evaluation of the impacts of climate change to secure long-term benefits provided by urban forests
... Cumulatively, these threats put the sustainability of south Texas water resources at risk, escalating pressure on agricultural stakeholders to minimize water losses, which often requires investments or tradeoffs too costly for many irrigation districts or producers to consider (e.g., relining ditches or replacing failing pipe systems in the irrigated areas, or investing in alternative nutrient management or cropping systems in the dryland areas). Research from similar contexts around the world has shown that attempting to solve any one of these issues in isolation has led to far-reaching, unintended ecologic, hydrologic, or economic consequences (e.g., reduced ecosystem services as result of effort to minimize conveyance loses; greater per capita water use in the face of water rationing policy; increasing investment in agricultural land and therefore irrigation demand as a result of investment in maximizing irrigation efficiency) (Gohari et al. 2013;Breyer et al. 2018;Di Baldassarre et al. 2018;Grafton et al. 2018). ...
The Coastal Bend (CB), Lower Rio Grande Valley (LRGV), and Wintergarden (WG) subregions of south Texas co-exist in similar socioeconomic contexts but rely on markedly different water sources (CB: precipitation; LRGV: surface water; WG: groundwater). This has led to unique agricultural practices and municipal policies and reinforced mental models adapted specifically to each subregion, both of which are critical to understanding structural causes behind current water use and future water sustainability. To better stakeholder mental models in each subregion, semi-structured interviews were conducted with individuals with a significant stake in water resource use and management. Results indicated near unanimous consensus among farmers and other stakeholders that water supply is limited and will be increasingly stressed under continued urban population growth. Farmers expressed concern that it will become more difficult to continue farming if additional water resources are not available, while each subregion expressed their own unique concerns: growing bureaucratic oversight and growing population problems (CB), lack of inflows, poor water quality, and international disputes with Mexico (LRGV), and political subdivision, declining groundwater levels, and information technology costs (WG). Mental models were synthesized based on dominant themes expressed by respondents; we synthesized these into two systems thinking archetypes: Tragedy of the Commons and Success to the Successful. Though it is unreasonable to create blanket region-wide policies, the adoption of under-utilized conservation practices coupled to stakeholder outreach remains unexplored leverage points, given most stakeholders are unaware of the feedback processes continuing to threaten south Texas water resources.
Drinking water supply in rural areas remains a substantial challenge due to complex natural, technical and economic conditions. To provide safe and affordable drinking water to all, as targeted in the UN Sustainable Development Goals (2030 Agenda), low-cost, efficient water treatment processes suitable for rural areas need to be developed. In this study, a bubbleless aeration BAC (termed ABAC) process is proposed and evaluated, involving the incorporation of a hollow fiber membrane (HFM) assembly within a slow-rate BAC filter, to provide dissolved oxygen (DO) throughout the BAC filter and an increased DOM removal efficiency. The results showed that after a 210-day period of operation, the ABAC increased the DOC removal by 54%, and decreased the disinfection byproduct formation potential (DBPFP) by 41%, compared to a comparable BAC filter without aeration (termed NBAC). The elevated DO (> 4 mg/L) not only reduced secreted extracellular polymer, but also modified the microbial community with a stronger degradation ability. The HFM-based aeration showed comparable performance to 3 mg/L pre-ozonation, and the DOC removal efficiency was four times greater than that of a conventional coagulation process. The proposed ABAC treatment, with its various advantages (e.g., high stability, avoidance of chemicals, ease of operation and maintenance), is well-suited to be integrated as a prefabricated device, for decentralized drinking water systems in rural areas.
Taking sustainable solar energy for efficient rapid clean water production is eagerly desired to overcome the water shortage issue. However, great challenges remain in constructing short water transport channels and enhancing sunlight utilization efficiency. Herein, a biomimetic solar-driven interfacial evaporator with rapid water transport and high photothermal conversion efficiency inspired by natural-trees was successfully developed, via engineer vertically aligned hydrophilic sodium alginate (SA) aerogels while hierarchically assembled MXene interwoven carbon nanotube (CNT) networks as micro/nano light absorb layer. Due to the synergistic photothermal effect between 2D MXene nanosheets and 1D CNT with multiple reflective nanostructure and strong light-absorption over a broad spectrum, and super-hydrophilic SA with highly oriented water transport channels, which enables fast water/vapor transport while utilizing solar energy efficiently. Vertically aligned aerogel exhibits an excellent water evaporation performance which as high as 2.416 kg m⁻² h⁻¹ (deducting dark conditions) and remarkable solar energy utilizing efficiency of 90.56 %, which are extremely higher than that of most reported desalination devices. Furthermore, the solar-driven evaporator also exhibits strong antibacterial properties and long-term operation stability. The biomimetic vertically aligned aerogel with excellent water evaporation and light utilization efficiency holds great promise for high-performance water purification and desalination applications. Synopsis statement: Research on the rapid clean water production from wastewater/seawater with high solar energy utilization efficiency has become a hot topic, and solar-driven desalination offers a sustainable solution to meet water demands. This study reports a biomimetic solar-driven interfacial evaporator with oriented water transport nanochannel and multi-reflective solar absorber for efficient clean water production.
This paper shares an early-career perspective on potential themes for the upcoming International Association of Hydrological Sciences (IAHS) scientific decade (SD). This opinion paper synthesizes six discussion sessions in western Europe identifying three themes that all offer a different perspective on the hydrological threats the world faces and could serve to direct the broader hydrological community: “Tipping points and thresholds in hydrology”, “Intensification of the water cycle”, and “Water services under pressure”. Additionally, four trends were distinguished concerning the way in which hydrological research is conducted: big data, bridging science and practice, open science, and inter- and multidisciplinarity. These themes and trends will provide valuable input for future discussions on the theme for the next IAHS SD. We encourage other Early-Career Scientists to voice their opinion by organizing their own discussion sessions and commenting on this paper to make this initiative grow from a regional initiative to a global movement.
Dams and reservoirs are human-made infrastructures that have attracted increasing attentions because of their societal and environmental significance. Towards better management and conservation of reservoirs, a dataset of reservoir-catchment characteristics is needed, considering that the amount water and material flowing into and out of reservoirs depends on their locations on the river network and the properties of upstream catchment. To date, no dataset exists for reservoir-catchment characteristics. The aim of this study is to develop the first database featuring reservoir-catchment characteristics for 3254 reservoirs with storage capacity totaling 682,595 km3 (73.2% reservoir water storage capacity in China), to support the management and conservation of reservoirs in the context of catchment level. To ensure a more representative and accurate mapping of local variables of large reservoirs, reservoir catchments are delineated into full catchments (their full upstream contributing areas) and intermediate catchments (subtracting the area contributed by upstream reservoirs from full upstream of the current reservoir). Using both full catchments and intermediate catchments, characteristics of reservoir catchments were extracted, with a total of 512 attributes in six categories (i.e., reservoir catchment, topography, climate, soil and geology, land cover and use, and anthropogenic activity). Besides these static attributes, time series of 15 meteorological variables of catchments were extracted to support hydrological simulations for a better understanding of drivers of reservoir environment change. Moreover, we provide a comprehensive and extensive reservoir data set on water level (data available for 20% of 3,254 reservoirs), water area (99%), storage anomaly (92%), and evaporation (98%) from multisource satellites such as radar and laser altimeters and images from Landsat and Sentinel satellites. These products significantly enhance spatial and temporal coverage in comparison to existing similar products (e.g., 67% increase in spatial resolution of water level and 225% increase in storage anomaly) and contribute to our understanding of reservoir properties and functions within the Earth system by incorporated national or global hydrological modeling. In situ data of 138 reservoirs are employed in this study as a valuable reference for evaluation, thus enhancing our confidence in the data quality and enhancing our understanding of accuracy of current satellite datasets. Along with its extensive attributes, the Reservoir dataset in China (Res-CN) can support a broad range of applications such as water resources, hydrologic/hydrodynamic modeling, and energy planning. Res-CN is on Zenodo through https://doi.org/10.5281/zenodo.7390715 (Shen et al., 2022a).
The massive discharge of oily wastewater and oil spills are causing serious pollution to water resources. It is urgent to require clean and efficient method of purifying oily emulsions. Although the separation membranes with selective wettability have been widely used in the efficient purification of oil/water emulsions. It is still very challenging to develop functional films that are environmentally friendly, fouling resistant, inexpensive, easy to prepare, easy to scale, and highly efficient. Cellulose nanocrystalline-based composite membranes (CCM) were prepared by surface-initiated atom transfer radical polymerization (SATRP) and vacuum self-assembly. The prepared CCM is superhydrophilic and superoleophobic underwater due to the hydrophilic nature of the modified cellulose-nanocrystalline and the micro-nano surface structure. The CCM shows high separation efficiency (> 99.9 %), high flux (16,692 L-1·m-2·h-1·bar-1) for surfactant-stabilized oil-in-water emulsions, good cycle stability and anti-fouling performance. This biomass-derived membrane is green, cheap, easy to manufacture, scalable, super-wettability, and durability, it promises to be an alternative to separation membranes in today's market.
In situations of fluctuating water availability, the optimal reservoir operation policy, resulting from classical models, fails to be implemented for political reasons. This paper proposes a collaborative modeling approach to define the hedging rules of a two-basin reservoir system, in which the acceptable risks, rationing ratio, and reasonable transfer values are defined by the water allocation agents for different phases/drought states. An optimization algorithm is then applied to determine a politically viable hedging operation policy. The methodology showed good results for the Jaguaribe–Metropolitan system in Brazil, and the resulting policy could be applied to the real operation, as the simulated rationing frequencies were close to those defined by the managers’ consensus. The proposed methodology guarantees a politically viable alternative with conflict management possibilities. However, the performance of the resulting hedging rules depends on the negotiation capacity and tacit knowledge of the stakeholders. The proposed approach is a good alternative when the implementation of the mathematically optimum policy fails.
La primera usina de generación hidroeléctrica conocida como represa "Dr. Gabriel Terra", que se instaló sobre el Río Negro (Río Hum para los indígenas) en 1945, inundó las zonas más bajas a su alrededor y modificó el paisaje natural del Paso Polanco en el Departamento de Tacuarembó. Desde entonces, el Hum se ensanchó formando un gran lago de aproximadamente 120 mil hectáreas y transformó al pueblo allí establecido en el hoy reconocido balneario turístico San Gregorio de Polanco. De esa forma, la obra transformó el paisaje natural que allí existía en un ambiente modificado por el hombre y dejó una huella ambiental and socioeconómica que no sólo sería irreversible sino que daría lugar a cambios comparativamente más severos que impactaron aún más el ecosistema del río, y produjeron una gradual contaminación de sus aguas. El embalse del Río Hum estuvo inicialmente dirigido a la producción de energía hidroeléctrica, pero es también utilizado como fuente de agua para el consumo humano, para abastecer al turismo y a sectores como la pesca y la cría artificial de peces para exportación, en general aspectos que pueden considerarse como positivos para la comunidad. No obstante, la construcción de esta obra afectó considerablemente el monte ribereño, impactó el hábitat de muchas especies de la fauna autóctona tanto acuática como terrestre y produjo el desplazamiento obligado de gran parte de la población que tenía un proyecto de vida y perspectivas de prosperidad en su pueblo natal. Evidentemente, estas consecuencias representan el impacto negativo inmediato que dejó la represa para Rincón de Bonete, pero en la percepción de la población actual parecen ser, quizás por desconocimiento, poco significativas. El gran embalse ha atraído inversiones para desarrollar proyectos que se proponen como importantes para la economía de la región y del país como la producción de pasta de celulosa. Pero las derivaciones ambientales de estas actividades para con la preservación del ecosistema, son aún inciertas. El objeto de este trabajo es mostrar un panorama general del ecosistema del Río Hum y la población que se desarrollaba a su alrededor previo a la construcción de la represa en Rincón de Bonete, de manera de disponer de esa información en torno a la evaluación de la naturaleza de los cambios, tanto ambientales como sociales que están reflejados en el paisaje actual de la zona. Asimismo, se discuten las implicancias de la nueva dinámica hidráulica del río Hum post embalse, particularmente los procesos geomorfológicos del flujo que generaron un cambio en los patrones de erosión y depositación que influyeron en la geología del lugar, dejando al descubierto yacimientos paleozoicos portadores de importantes fósiles para nuestro patrimonio cultural que son descritos por primera vez en este trabajo.
We examined the effects of hydrological variables such as irrigation area, irrigation efficiency and water storage on the resilience of (mostly commercial) irrigated agriculture to drought in a semi-arid catchment in South Africa. We formulated a conceptual framework termed ‘Water, Efficiency, Resilience, Drought’ (WERD) and an accompanying spreadsheet model. These allow the resilience of irrigated agriculture to drought to be analysed via water accounts and a key resilience indicator termed Days to Day Zero (DDZ). This represents the number of days that a pre- and within-drought supply of catchment water available to irrigation is withdrawn down to zero in the face of a prolonged drought. A higher DDZ (e.g. >300 days) indicates greater resilience whilst a lower DDZ (e.g. <150 days) signals lower resilience. Drought resilience arises through land and water management decisions underpinned by four types of resilience capacities; absorptive, adaptive, anticipative and transformative. For the case study, analyses showed that irrigators, with currently approximately 23,000 ha under irrigation, have historically absorbed and adapted to drought events through construction of water storage and adoption of more efficient irrigation practices resulting in a DDZ of 260 days. However, by not fully anticipating future climate and water-related risks, irrigators are arguably on a maladaptive pathway resulting in water supply gains, efficiency and other practices being used to increase irrigation command areas to 28,000 ha or more, decreasing their capacity to absorb future droughts. This areal growth increases water withdrawals and consumption, further stresses the catchment and reduces future DDZs to approximately 130 days indicating much lower drought resilience. Our approach, supported by supplementary material, allows stakeholders to better understand the resilience consequences of future drought in order to; reconcile competition between rising water demands, consider new water storage; improve agricultural and irrigation planning; and enhance catchment governance.
Changes in the mountain cryosphere impact the water security of downstream societies and the resilience of water-dependent ecosystems and their services. However, assessing mountain water security requires better understanding of the complex interaction between glacial meltwater and coupled human–natural systems. In this context, we call for a refocusing from glacio-hydrological monitoring and modelling to a more integrated social ecological perspective of the wider catchment hydrology. This shift requires locally relevant knowledge-production strategies and the integration of such knowledge into a collaborative science–policy–community framework. This approach, combined with hydrological risk assessment, can support the development of robust, locally tailored and transformational adaptation strategies.
With exacerbating climate change, the current reservoir storage capacity in South Korea is insufficient to meet the future scheduled water demand. No study has yet evaluated the effects of applying the water supply adjustment standard (Standard) and activating the reservoir emergency storage in response to extreme drought. The main objective is to assess the effects of applying Standard and activating emergency storage in meeting the water demand under extreme drought at six multipurpose reservoirs (Andong, Gimcheon-Buhang, Gunwi, Hapcheon, Imha, and Milyang) in the Nakdong River Basin, South Korea. We built a reservoir simulation model (HEC-ResSim), determined the extreme drought scenarios, and emergency storage capacity. We evaluated three reservoir operation cases (general operation, regular Standard, and revised Standard) from 2011 to 2100. The results show that applying the Standard and activating the emergency storage are effective in meeting the future water demand during extreme drought. In conclusion, we need to secure 110 million cubic meters (MCM) (Hapcheon reservoir) and 8 MCM (Gunwi reservoir) of water to reduce the number of days in the emergency stage. This research serves as a fundamental study that can help establish Standard and emergency storage activation criteria for other multipurpose reservoirs in preparation for extreme drought.
Water diversion projects are an effective measure to mitigate water shortages in water-limited areas. Understanding the risk of such projects increasing concurrent drought between the water intake and receiving regions is essential for sustainable water management. This study calculates concurrent drought probability between the water intake and receiving regions of the Hanjiang to Weihe River Water Diversion Project using Standardized Precipitation Index and Copula functions. Results showed an increasing trend in drought probability across both the water intake and receiving regions from 2.67% and 8.38% to 12.47% and 14.18%, respectively, during 1969–2018. The return period of concurrent drought decreased from 111.11 to 13.05 years, indicating larger risk of simultaneous drought between the two regions. Projections from CMIP6 suggested that under the SSP 2–4.5 and 5–8.5 scenarios, concurrent drought probability would increase by 2.40% and 7.72% in 2019–2050 compared to that in 1969–1990, respectively. Although increases in precipitation during 2019–2050 could potentially alleviate drought conditions relative to those during 1991–2018, high precipitation variability adds to the uncertainty about future concurrent drought. These findings provide a basis for better understanding concurrent drought and its impact on water diversion projects in a changing climate, and facilitate the establishment of adaptation countermeasures to ensure sustainable water availability.
Increased variability of the water cycle manifested by climate change is a growing global threat to agriculture with strong implications for food and livelihood security. Thus, there is an urgent need for adaptation in agriculture. Agricultural water management (AWM) interventions, interventions for managing water supply and demand, are extensively promoted and implemented as adaptation measures in multiple development programs globally. Studies assessing these adaptation measures overwhelmingly focus on positive impacts, however, there is a concern that these studies may be biased towards well-managed and successful projects and often miss out on reporting negative externalities. These externalities result from coevolutionary dynamics of human-water systems as AWM interventions impact hydrological flows and their use and adoption is shaped by the societal response. We review the documented externalities of AWM interventions and present a conceptual framework classifying negative externalities linked to water and human systems into negative hydrological externalities and unexpected societal feedbacks. We show that these externalities can lead to long term unsustainable and inequitable outcomes. Understanding how the externalities lead to undesirable outcomes demands rigorous modeling of the feedbacks between human and water systems, for which we discuss the key criteria that such models should meet. Based on these criteria, we showcase that differentiated and limited inclusion of key feedbacks in current water modeling approaches (e.g., hydrological models, hydro-economic, and water resource models) is a critical limitation and bottleneck to understanding and predicting negative externalities of AWM interventions. To account for the key feedback, we find Agent Based Modeling (ABM) as the method that has the potential to meet the key criteria. Yet there are gaps that need to be addressed in the context of ABM as a tool to unravel the negative externalities of AWM interventions. We carry out a systemic review of ABM application to agricultural systems, capturing how it is currently being applied and identifying the knowledge gaps that need to be bridged to unravel the negative externalities of AWM interventions. We find that ABM has been extensively used to model agricultural systems and, in many cases, the resulting externalities with unsustainable and inequitable outcomes. However, gaps remain in terms of limited use of integrated surface-groundwater hydrological models, inadequate representation of farmers' behavior with heavy reliance on rational choice or simple heuristics and ignoring heterogeneity of farmers' characteristics within a population.
The rapid shrinkage of Lake Urmia, one of the world's largest saline lakes located in northwestern Iran, is a tragic wake-up call to revisit the principles of water resources management based on the socio-economic and environmental dimensions of sustainable development. The overarching goal of this paper is to set a framework for deriving dynamic, climate-informed environmental inflows for drying lakes considering both meteorological/climatic and anthropogenic conditions. We report on the compounding effects of meteorological drought and unsustainable water resource management that contributed to Lake Urmia's contemporary environmental catastrophe. Using rich datasets of hydrologic attributes, water demands and withdrawals, as well as water management infrastructure (i.e. reservoir capacity and operating policies), we provide a quantitative assessment of the basin's water resources, demonstrating that Lake Urmia reached a tipping point in the early 2000s. The lake level failed to rebound to its designated ecological threshold (1274 m above sea level) during a relatively normal hydro-period immediately after the drought of record (1998-2002). The collapse was caused by a marked overshoot of the basin's hydrologic capacity due to growing anthropogenic drought in the face of extreme climatological stressors. We offer a dynamic environmental inflow plan for different climate conditions (dry, wet and near normal), combined with three representative water withdrawal scenarios. Assuming effective implementation of the proposed 40% reduction in the current water withdrawals, the required environmental inflows range from 2900 million cubic meters per year (mcm yr⁻¹) during dry conditions to 5400 mcm yr⁻¹ during wet periods with the average being 4100 mcm yr⁻¹. Finally, for different environmental inflow scenarios, we estimate the expected recovery time for re-establishing the ecological level of Lake Urmia.
Urban water demand will increase by 80% by 2050, while climate change will alter the timing and distribution of water. Here we quantify the magnitude of these twin challenges to urban water security, combining a dataset of urban water sources of 482 of the world’s largest cities with estimates of future water demand, based on the Intergovernmental Panel on Climate Change (IPCC)’s Fifth Assessment scenarios, and predictions of future water availability, using the WaterGAP3 modelling framework. We project an urban surface-water deficit of 1,386–6,764 million m³. More than 27% of cities studied, containing 233 million people, will have water demands that exceed surface-water availability. An additional 19% of cities, which are dependent on surface-water transfers, have a high potential for conflict between the urban and agricultural sectors, since both sectors cannot obtain their estimated future water demands. In 80% of these high-conflict watersheds, improvements in agricultural water-use efficiency could free up enough water for urban use. Investments in improving agricultural water use could thus serve as an important global change adaptation strategy. Rising population and changes in water supply under climate change affect cities globally. This study finds that in 27% of cities studied, water demand is likely to exceed availability by 2050, with many other cities competing with agriculture on water needs.
This study explores a general framework for quantifying anthropogenic influences on groundwater budget based on normalized human outflow (hout) and inflow (hin). The framework is useful for sustainability assessment of groundwater systems and allows investigating the effects of different human water abstraction scenarios on the overall aquifer regime (e.g., depleted, natural flow-dominated, and human flow-dominated). We apply this approach to selected regions in the USA, Germany and Iran to evaluate the current aquifer regime. We subsequently present two scenarios of changes in human water withdrawals and return flow to the system (individually and combined). Results show that approximately one-third of the selected aquifers in the USA, and half of the selected aquifers in Iran are dominated by human activities, while the selected aquifers in Germany are natural flow-dominated. The scenario analysis results also show that reduced human withdrawals could help with regime change in some aquifers. For instance, in two of the selected USA aquifers, a decrease in anthropogenic influences by ~20% may change the condition of depleted regime to natural flow-dominated regime. We specifically highlight a trending threat to the sustainability of groundwater in northwest Iran and California, and the need for more careful assessment and monitoring practices as well as strict regulations to mitigate the negative impacts of groundwater overexploitation.
Hydropower is the most important renewable energy source to date, providing over 72% of all renewable electricity globally. Yet, only limited information is available on the global potential supply of hydropower and the associated costs. Here we provide a high-resolution assessment of the technical and economic potential of hydropower at a near-global scale. Using 15”×15” discharge and 3”×3” digital elevation maps, we built virtual hydropower installations at >3.8 million sites across the globe and calculated their potential using cost optimization methods. This way we identified over 60,000 suitable sites, which together represent a remaining global potential of 9.49 PWh yr⁻¹ below US$0.50 kWh⁻¹. The largest remaining potential is found in Asia Pacific (39%), South America (25%) and Africa (24%), of which a large part can be produced at low cost (<US$0.10 kWh⁻¹). In an ecological scenario, this potential is reduced to 5.67 PWh yr⁻¹.
Observed changes in precipitation patterns, rising surface temperature, increases in frequency and intensity of floods and droughts, widespread melting of ice, and reduced snow cover are some of the documented hydrologic changes associated with global climate change. Climate change is therefore expected to affect the water supply-demand balance in the Northeast United States and challenge existing water management strategies. The hydrological implications of future climate will affect the design capacity and operating characteristics of dams. The vulnerability of water resources systems to floods and droughts will increase, and the trade-offs between reservoir releases to maintain flood control storage, drought resilience, ecological flow, human water demand, and energy production should be reconsidered. We used a Neural Networks based General Reservoir Operation Scheme to estimate the implications of climate change for dams on a regional scale. This dynamic daily reservoir module automatically adapts to changes in climate and re-adjusts the operation of dams based on water storage level, timing, and magnitude of incoming flows. Our findings suggest that the importance of dams in providing water security in the region will increase. We create an indicator of the Effective Degree of Regulation (EDR) by dams on water resources and show that it is expected to increase, particularly during drier months of year, simply as a consequence of projected climate change. The results also indicate that increasing the size and number of dams, in addition to modifying their operations, may become necessary to offset the vulnerabilities of water resources systems to future climate uncertainties. This is the case even without considering the likely increase in future water demand, especially in the most densely populated regions of the Northeast.
Water scarcity is rapidly increasing in many regions. In a novel, multi-model assessment, we examine how human interventions (HI: land use and land cover change, man-made reservoirs and human water use) affected monthly river water availability and water scarcity over the period 1971–2010. Here we show that HI drastically change the critical dimensions of water scarcity, aggravating water scarcity for 8.8% (7.4–16.5%) of the global population but alleviating it for another 8.3% (6.4–15.8%). Positive impacts of HI mostly occur upstream, whereas HI aggravate water scarcity downstream; HI cause water scarcity to travel downstream. Attribution of water scarcity changes to HI components is complex and varies among the hydrological models. Seasonal variation in impacts and dominant HI components is also substantial. A thorough consideration of the spatially and temporally varying interactions among HI components and of uncertainties is therefore crucial for the success of water scarcity adaptation by HI.
More than a hundred hydropower dams have already been built in the Amazon basin and numerous proposals for further dam constructions are under consideration. The accumulated negative environmental effects of existing dams and proposed dams, if constructed, will trigger massive hydrophysical and biotic disturbances that will affect the Amazon basin’s floodplains, estuary and sediment plume. We introduce a Dam Environmental Vulnerability Index to quantify the current and potential impacts of dams in the basin. The scale of foreseeable environmental degradation indicates the need for collective action among nations and states to avoid cumulative, far-reaching impacts. We suggest institutional innovations to assess and avoid the likely impoverishment of Amazon rivers.
Over the last few decades, numerous studies have
investigated human impacts on drought and flood events, while conversely
other studies have explored human responses to hydrological extremes. Yet,
there is still little understanding about the dynamics resulting from their
interplay, i.e. both impacts and responses. Current quantitative methods
therefore can fail to assess future risk dynamics and, as a result, while
risk reduction strategies built on these methods often work in the short
term, they tend to lead to unintended consequences in the long term. In this
paper, we review the puzzles and dynamics resulting from the interplay of
society and hydrological extremes, and describe an initial effort to model
hydrological extremes in the Anthropocene. In particular, we first discuss
the need for a novel approach to explicitly account for human interactions
with both drought and flood events, and then present a stylized model
simulating the reciprocal effects between hydrological extremes and changing
reservoir operation rules. Lastly, we highlight the unprecedented
opportunity offered by the current proliferation of big data to unravel the
coevolution of hydrological extremes and society across scales and along
gradients of social and hydrological conditions.
With population growth, increasing water demands and climate change the need to understand the current and future pathways to water security is becoming more pressing. To contribute to addressing this challenge, we examine the link between water stress and society through socio-hydrological modeling. We conceptualize the interactions between an agricultural society with its environment in a stylized way. We apply the model to the case of the ancient Maya, a population that experienced a peak during the Classic Period (AD 600-830) and then declined during the ninth century. The hypothesis that modest drought periods played a major role in the society's collapse is explored. Simulating plausible feedbacks between water and society we show that a modest reduction in rainfall may lead to an 80% population collapse.Population density and crop sensitivity to droughts, however, may play an equally important role. The simulations indicate that construction of reservoirs results in less frequent drought impacts, but if the reservoirs run dry, drought impact may be more severe and the population drop may be larger. Index terms: 1812 Drought (4303) 1834 Human impacts (4323) 4330 Vulnerability. Keywords: socio-hydrology, Ancient Maya, drought, vulnerability. This article is protected by copyright. All rights reserved.
The global water cycle has been profoundly affected by human land?water management. As the changes in the water cycle on land can affect the functioning of a wide range of biophysical and biogeochemical processes of the Earth system, it is essential to represent human land?water management in Earth system models (ESMs). During the recent past, noteworthy progress has been made in large-scale modeling of human impacts on the water cycle but sufficient advancements have not yet been made in integrating the newly developed schemes into ESMs. This study reviews the progresses made in incorporating human factors in large-scale hydrological models and their integration into ESMs. The study focuses primarily on the recent advancements and existing challenges in incorporating human impacts in global land surface models (LSMs) as a way forward to the development of ESMs with humans as integral components, but a brief review of global hydrological models (GHMs) is also provided. The study begins with the general overview of human impacts on the water cycle. Then, the algorithms currently employed to represent irrigation, reservoir operation, and groundwater pumping are discussed. Next, methodological deficiencies in current modeling approaches and existing challenges are identified. Furthermore, light is shed on the sources of uncertainties associated with model parameterizations, grid resolution, and datasets used for forcing and validation. Finally, representing human land?water management in LSMs is highlighted as an important research direction toward developing integrated models using ESM frameworks for the holistic study of human?water interactions within the Earths system. WIREs Water 2016, 3:548?574. doi: 10.1002/wat2.1150 For further resources related to this article, please visit the WIREs website.
Drought management is inefficient because feedbacks between drought and people are not fully understood. In this human-influenced era, we need to rethink the concept of drought to include the human role in mitigating and enhancing drought.
Flow regulation and irrigation alter local freshwater conditions, but their global effects are highly uncertain. We investigated these global effects from 1901 to 2008, using hydroclimatic observations in 100 large hydrological basins. Globally, we find consistent and dominant effects of increasing relative evapotranspiration from both activities, and decreasing temporal runoff variability from flow regulation. The evapotranspiration effect increases the long-term average human consumption of fresh water by 3563 ± 979 km3/year from 1901–1954 to 1955–2008. This increase raises a recent estimate of the current global water footprint of humanity by around 18%, to 10,688 ± 979 km3/year. The results highlight the global impact of local water-use activities and call for their relevant account in
Earth system modeling.
http://www.su.se/profiles/fjara-1.188044
Societies and economies are challenged by variable water supplies. Water storage infrastructure, on a range of scales, can help to mitigate hydrological variability. This study uses a water balance model to investigate how storage capacity can improve water security in the world's 403 most important river basins, by substituting water from wet months to dry months. We construct a new water balance model for 676 'basin-country units' (BCUs), which simulates runoff, water use (from surface and groundwater), evaporation and trans-boundary discharges. When hydrological variability and net withdrawals are taken into account, along with existing storage capacity, we find risks of water shortages in the Indian subcontinent, Northern China, Spain, the West of the US, Australia and several basins in Africa. Dividing basins into BCUs enabled assessment of upstream dependency in transboundary rivers. Including Environmental Water Requirements into the model, we find that in many basins in India, Northern China, South Africa, the US West Coast, the East of Brazil, Spain and in the Murray basin in Australia human water demand leads to over-abstraction of water resources important to the ecosystem. Then, a Sequent Peak Analysis is conducted to estimate how much storage would be needed to satisfy human water demand whilst not jeopardizing environmental flows. The results are consistent with the water balance model in that basins in India, Northern China, Western Australia, Spain, the US West Coast and several basins in Africa would need more storage to mitigate water supply variability and to meet water demand.
Energy Policy, 69 + (2014) 43-56. doi:10.1016/j.enpol.2013.10.069
California's current extreme drought must be a lesson for managing water in a warmer, more densely populated world, say Amir AghaKouchak and colleagues.
Over the past few decades, urban areas of the American West have experienced some of the highest population growth rates in the country. To manage the attendant impacts on housing, transportation, and quality of life, some cities have diverged from the low-density “sprawl” model of postwar urban development, and instead have attempted to manage spatial growth, increase density in downtown cores, use alternative transportation options, and protect the natural environment. These cities, in contrast to their counterparts in the Southwest and Sun Belt, could provide critical lessons for urban theorists and planners on how cities can adapt and thrive in a century that may be dominated by economic and, increasingly, ecological concerns. Using demographic data and journalistic reportage to address both macro- and micro-scale shifts in these cities, this article seeks to use and supplement the growing literature on smart growth and sustainable development by examining four cities in the American West—Seattle, Portland (Oregon), Salt Lake City, and Denver—to gauge how transit, smart growth, and an emphasis on quality of life, outdoor recreation, and environmental health can lead to sustainable population and economic growth.
Water availability and use are inherently regional concerns. However, a global-scale approach to evaluating strategies to reduce water stress can help maximize mitigation.
Climate change very likely impacts future hydrological drought
characteristics across the world. Here, we quantify the impact of
climate change on future low flows and associated hydrological
drought characteristics on a global scale using an alternative
drought identification approach that considers adaptation to future
changes in hydrological regime. The global hydrological model
PCR-GLOBWB was used to simulate daily discharge at 0.5°
globally for 1971–2099. The model was forced with CMIP5 climate
projections taken from five global circulation models (GCMs) and four emission scenarios (representative concentration pathways, RCPs),
from the Inter-Sectoral Impact Model Intercomparison Project.
Drought events occur when discharge is below a threshold. The
conventional variable threshold (VTM) was calculated by deriving the
threshold from the period 1971–2000. The transient variable
threshold (VTMt) is a non-stationary approach,
where the threshold is based on the discharge values of the previous
30 years implying the threshold to vary every year during the 21st
century. The VTMt adjusts to gradual changes in
the hydrological regime as response to climate change.
Results show a significant negative trend in the low flow regime
over the 21st century for large parts of South America, southern
Africa, Australia and the Mediterranean. In 40–52% of the
world reduced low flows are projected, while increased low flows are
found in the snow-dominated climates.
In 27% of the global area both the drought duration and the
deficit volume are expected to increase when applying the
VTMt. However, this area will significantly
increase to 62% when the VTM is applied. The mean global area
in drought, with the VTMt, remains rather
constant (11.7 to 13.4%), compared to the substantial
increase when the VTM is applied (11.7 to 20%).
The study illustrates that an alternative drought identification
that considers adaptation to an altered hydrological regime has
a substantial influence on future hydrological drought characteristics.
Lake Urmia, one of the largest saltwater lakes on earth and a highly endangered ecosystem, is on the brink of a major environmental disaster similar to the catastrophic death of the Aral Sea. With a new composite of multi-spectral high resolution satellite observations, we show that the area of this Iranian lake has decreased by around 88% in the past decades, far more than previously reported (~ 25% to 50%). The lake's shoreline has been receding severely with no sign of recovery, which has been partly blamed on prolonged droughts. We use the lake basin's satellite-based gauge-adjusted climate record of the Standardized Precipitation Index data to demonstrate that the on-going shoreline retreat is not solely an artifact of prolonged droughts alone. Drastic changes to lake health are primarily consequences of aggressive regional water resources development plans, intensive agricultural activities, anthropogenic changes to the system, and upstream competition over water. This commentary is a call for action to both develop sustainable restoration ideas and to put new visions and strategies into practice before Lake Urmia falls victim to the Aral Sea syndrome.
The hypothesis of a rebound effect as a consequence of water saving investments is taken analogically from the Jevons paradox models in energy economics. The European Commission (EC) alert about the consequences in water stressed regions that are investing heavily in modernization of irrigation networks and systems. This paper reviews the literature, linking water savings with water diversion and water depletion, both from theoretical models and empirical evidence from the published
research. In order to increase knowledge of this phenomenon, a new empirical case study is presented based on a survey of 36,000 ha of recently modernized irrigated areas in the Guadalquivir basin (southern Spain). The results of the case study illustrates the conditions that may avoid rebound effect, although the results of the available empirical evidence and the published theoretical research are diverse and lead to contradictory results. Further research is therefore needed to determine the causes and solutions of water saving investment impacts and the possible speculative rebound effect.
Improving the efficiency of water use is usually presented as an opportunity for large water savings, particularly in the agricultural sector. Warnings that this may not translate into reduced consumption is sometimes associated with the rebound effect or Jevons paradox, an appealing concept that can be used to analyse and prevent unde ired consequences in the rush for efficiency gains. This article, based on the energy sector, shows that the concept helps to identify possible unintended consequences of increasing efficiency and shows how efficiency gains are shared in society. However, it might be conceptually misleading when applied to water since it reinforces a myth on the consideration of water savings and efficiency, and may be also too restrictive. The recent modernisation of irrigation practices in Spain highlights that the rebound effect is only one of many possible consequences of efficiency improvements.
High social, environmental and financial costs of dam construction during the past century provide valuable lessons for improving large infrastructure governance and enhancing dam safety. The Italian Vajont dam tragedy in 1963, for example, where the urgency to boost post-war economic development overruled cautionary site selection and reservoir filling, led to improved safety regulations. Today, Afghanistan is facing similar pressure to spur economic development. Revisiting Afghanistan’s own dam history may inform decision-making over large scale dam development. For this, we refer to dam development in Afghanistan during the Cold War institutional constellation, which combined with the discourse on the role of dams in state formation, modernisation and development, profoundly shaped Afghanistan’s landscape. Current dam development shows little evidence that any historic reflection is taking place; instead the discourse of infrastructure-as-prerequisite-for-development is consistently repeated. We argue that four factors compromise dam development in Afghanistan today: (1) lack of security; (2) an institutional context under transition; (3) absence of transboundary dialogue and agreements and (4) uncertain and fragmented aid provision. The complexity of dam development and operation is exacerbated by the extended temporal and spatial scale of their impact, thus placing a heavy burden on management- and planning capacity. Given these conditions, these dam development plans are built on fragile institutional foundations. To address their feasibility under such circumstances this paper links lessons from the past with the criticalities in future Afghan dam development.
A brisk building boom of hydropower mega-dams is underway from China to Brazil. Whether benefits of new dams will outweigh costs remains unresolved despite contentious debates. We investigate this question with the “outside view” or “reference class forecasting” based on literature on decision-making under uncertainty in psychology. We find overwhelming evidence that budgets are systematically biased below actual costs of large hydropower dams—excluding inflation, substantial debt servicing, en-vironmental, and social costs. Using the largest and most reliable reference data of its kind and multilevel statistical techniques applied to large dams for the first time, we were successful in fitting parsimonious models to pre-dict cost and schedule overruns. The outside view suggests that in most countries large hydropower dams will be too costly in absolute terms and take too long to build to deliver a positive risk-adjusted return unless suita-ble risk management measures outlined in this paper can be affordably pro-vided. Policymakers, particularly in developing countries, are advised to prefer agile energy alternatives that can be built over shorter time horizons to energy megaprojects.
Risks from extreme weather events are mediated through state, civil
society and individual action. We propose evolving social contracts as a
primary mechanism by which adaptation to climate change proceeds. We use
a natural experiment of policy and social contexts of the UK and Ireland
affected by the same meteorological event and resultant flooding in
November 2009. We analyse data from policy documents and from household
surveys of 356 residents in western Ireland and northwest England. We
find significant differences between perceptions of individual
responsibility for protection across the jurisdictions and between
perceptions of future risk from populations directly affected by
flooding events. These explain differences in stated willingness to take
individual adaptive actions when state support retrenches. We therefore
show that expectations for state protection are critical in mediating
impacts and promoting longer-term adaptation. We argue that making
social contracts explicit may smooth pathways to effective and
legitimate adaptation.
As the world's largest distributed store of fresh water, ground water
plays a central part in sustaining ecosystems and enabling human
adaptation to climate variability and change. The strategic importance
of ground water for global water and food security will probably
intensify under climate change as more frequent and intense climate
extremes (droughts and floods) increase variability in precipitation,
soil moisture and surface water. Here we critically review recent
research assessing the impacts of climate on ground water through
natural and human-induced processes as well as through
groundwater-driven feedbacks on the climate system. Furthermore, we
examine the possible opportunities and challenges of using and
sustaining groundwater resources in climate adaptation strategies, and
highlight the lack of groundwater observations, which, at present,
limits our understanding of the dynamic relationship between ground
water and climate.
Freshwater scarcity has been cited as the major crisis of the 21st
century, but it is surprisingly hard to describe the nature of the
global water crisis. We conducted a meta-analysis of 22 coupled
human-water system case studies, using qualitative comparison analysis
(QCA) to identify water resource system outcomes and the factors that
drive them. The cases exhibited different outcomes for human wellbeing
that could be grouped into a six "syndromes": groundwater depletion,
ecological destruction, drought-driven conflicts, unmet subsistence
needs, resource capture by elite, and water reallocation to nature. For
syndromes that were not successful adaptations, three characteristics
gave cause for concern: (1) unsustainability—a decline in the
water stock or ecosystem function that could result in a long-term steep
decline in future human wellbeing; (2) vulnerability—high
variability in water resource availability combined with inadequate
coping capacity, leading to temporary drops in human wellbeing; (3)
chronic scarcity—persistent inadequate access and hence low
conditions of human wellbeing. All syndromes could be explained by a
limited set of causal factors that fell into four categories: demand
changes, supply changes, governance systems, and
infrastructure/technology. By considering basins as members of syndrome
classes and tracing common causal pathways of water crises, water
resource analysts and planners might develop improved water policies
aimed at reducing vulnerability, inequity, and unsustainability of
freshwater systems.