Article

Re-Thinking Environmental Flows: From Allocations and Reserves to Sustainability Boundaries

Authors:
To read the full-text of this research, you can request a copy directly from the author.

Abstract

Attempts to implement environmental flows have encountered many obstacles. Many water allocation systems include a system of prioritization among water uses that generally does not favor environmental flow protection, or do not allow for protection of high flow events for ecological purposes. It has proven very difficult to implement complicated environmental flow prescriptions that attempt to mimic natural flow variability within water allocation systems. Additionally, many water allocation systems do not adequately address interconnections between surface water and groundwater, or releases from dams. It is time to re-think our approaches to protecting environmental flows. As with water quality protection, environmental flows should be viewed not as an “allocation” of water, but rather as a desirable outcome of integrated management of water and land resources for long-term sustainability. In this sense, environmental flows should be managed in a manner similar to water quality protection, in which the influences of diverse land and water use activities are regulated to ensure that the ecological and social values of water are optimized. Both water quality and environmental flow management protect a vast array of important social benefits that are sustained by managing for healthy freshwater ecosystems. In this paper I offer a definition of sustainable water management that explicitly recognizes the fact that society derives substantial benefits both from out-of-stream extractions of water as well as by maintaining adequate flows of water within freshwater ecosystems. To help facilitate sustainable water management, a ”Sustainability Boundary Approach“ is described for use in setting quantitative water management goals. When the cumulative hydrologic impacts of water and land uses are managed within these sustainability boundaries, the full array of values associated with water can be more fully realized. Copyright © 2009 John Wiley & Sons, Ltd.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the author.

... Such methodologies are recommended in rivers with scarce development of water infrastructure for preventive flow protection (i.e. preventive or precautionary environmental water allocation), and to keep the regime's main ecological components and attributes within sustainable limits before that development takes place (Richter 2010, Richter et al. 2012, Acreman et al. 2014a, Poff et al. 2017, Opperman et al. 2018. ...
... It is based on the analysis of the characteristic pattern of a river's flow quantity, timing and variability. These are key hydrological features for regulating ecological processes in flow-dependent ecosystems and for building practical flow-ecology relationships in eflow assessments (Poff et al. 1997, Richter et al. 1997, Richter 2010, Postel and Richter 2003, Mathews and Richter 2007, Poff and Zimmerman 2010, Stone and Menendez 2011, Poff et al. 2017. ...
... This hydrology-based approach to eflow determination and further implementation was developed grounded in the opportunity, from a water management public policy context, to limit the flow alteration and unsustainable water abstraction through preventive water allocation in low-impacted systems (Poff et al. 2017, Salinas-Rodríguez et al. 2018. This scope has been an emerging trend in the last decade and aims to ensure a sustainable balance between water use and the conservation of aquatic ecosystems in river basins with unregulated or impaired flow (Postel and Richter 2003, Le Quesne et al. 2010, Richter 2010, Richter et al. 2012, Acreman et al. 2014a, Arthington et al. 2018a, 2018b, Opperman et al. 2018. The method aims to deliver "quick," science-based water volume requirements for ecosystems maintenance and sustainability, while fulfilling the two management requirements (discussed below) for feasible implementation under the Mexican system for allocating water. ...
Article
Full-text available
Hydrological methodologies are the most efficient approaches for environmental flow (eflow) assessments. This paper presents a hydrological methodology for determining eflows in rivers with scarce development to promote proactive environmental water allocations that limit flow alteration and unsustainable water use. The analysis includes the natural intra-annual and inter-annual ranges of flow variability. Eflows are determined based on four hydrological low-flow conditions and a flood regime. The main contribution is that the flow regime components are adjusted to a four-tiered environmental objective class system based on a novel ‘frequency-of-occurrence’ approach. The method is applied in three highly variable flow regime rivers in western Mexico. The eflows are largely (96%) within the central range from previous implementations and the outcomes reveal an overall good and acceptable level of the method’s performance (83% of the cases R ² ≥ 0.84, slope = 1 ± ≤ 0.2), consistent with supporting indices of flow variability.
... Under the ELOHA framework, the scientific and testable relationships between the hydrologic alteration and the ecological responses were established and used to develop the regional flow management standards. Even though ELOHA has balanced the scientific rigor and the application cost of many rivers in setting environmental flow standards, many governments could not (or would not) afford to apply ELOHA (typically ranging from $100,000 to $2 million) [2]. In addition, ELOHA could not be applied to many areas with low spatial coverage of biological data. ...
... In addition, ELOHA could not be applied to many areas with low spatial coverage of biological data. Therefore, Richter et al. [2,3] proposed the sustainable boundary approach (SBA) as a reference for the ecological flow management of these areas. The SBA, which is extended from the "percent-of-flow" approaches, proposes to set an allowable variation range called sustainable boundaries around the natural flow conditions as an approach to express the requirements of environmental flow management. ...
... Richter [2,3] suggested that the protection of environmental flows should be viewed as an integrated management of water resources for long-term sustainability, not as water distribution. From this point of view, the sustainable boundaries of ecological flow were established to protect the hydrological regime of rivers, and the ecological target is to maintain the flow within the sustainable boundaries. ...
Article
Full-text available
In this study, a model was proposed based on the sustainable boundary approach, to provide decision support for reservoir ecological operation with the dynamic Bayesian network. The proposed model was developed in four steps: (1) calculating and verifying the sustainable boundaries in combination with the ecological objectives of the study area, (2) generating the learning samples by establishing an optimal operation model and a Monte Carlo simulation model, (3) establishing and training a dynamic Bayesian network by learning the examples and (4) calculating the probability of the economic and ecological targets exceeding the set threshold from time to time with the trained dynamic Bayesian network model. Using the proposed model, the water drawing of the reservoir can be adjusted dynamically according to the probability of the economic and ecological targets exceeding the set threshold during reservoir operation. In this study, the proposed model was applied to the middle reaches of Heihe River, the effect of water supply proportion on the probability of the economic target exceeding the set threshold was analyzed, and the response of the reservoir water storage in each period to the probability of the target exceeding the set threshold was calculated. The results show that the risks can be analyzed with the proposed model. Compared with the existing studies, the proposed model provides guidance for the ecological operation of the reservoir from time to time and technical support for the formulation of reservoir operation chart. Compared with the operation model based on the designed guaranteed rate, the reservoir operation model based on uncertainty reduces the variation range of ecological flow shortage or the overflow rate and the economic loss rate by 5% and 6%, respectively. Thus, it can be seen that the decision support model based on the dynamic Bayesian network can effectively reduce the influence of water inflow and rainfall uncertainties on reservoir operation.
... The question then becomes whether flow regulations could revert this anthropogenic alteration and at the same time maintaining sufficient income streams to plant operators to finance their assets. To satisfy the need for specific targets in the development towards such a trade-off, ecologists developed the "Sustainability Boundary Approach" (SBA) as defined by ref. [39]. The SBA serves as a framework within which flow alterations are acceptable with the premise of securing the river's ecological integrity as much as possible. ...
... As the resulting flow patterns tend to lose their natural character, the question becomes whether flow regulations could revert this anthropogenic alteration and at the same time maintain sufficient income streams to plant operators to finance their assets. To satisfy the need for quantifiable targets in the development towards such a trade-off, ecologists developed so-called sustainability boundaries (SDB) and the concept of environmental flows [39,41]. SDBs serve as a framework within which flow alterations are acceptable with the premise of securing the river's ecological integrity as much as possible. ...
... SDBs serve as a framework within which flow alterations are acceptable with the premise of securing the river's ecological integrity as much as possible. SDBs are allowable percentages of deviation from the natural magnitude of flow [39]. To facilitate the cooperation with water managers SDBs were conceived as a hydrologically oversimplified but tangible parameter that can be specifically adapted to any given river [39]. ...
Article
Full-text available
The global energy system changes towards renewables-dominated and liberalized markets. This requires making novel trade-offs between the profitable development of hydropower and its environmental effects on the natural flow regime. Here, we used a pristine river as a model for how these future changes will affect the natural flow regime and identify future changes on previously overlooked levels. We found that damming and discharging based on market prices leads to first- and second-level deviation from natural flows. Beyond these effects, we identified a third level of distance from natural flow. This third level is created by the transition towards a renewables-dominated energy system. The volatile energy input from renewables incentivizes hydropower plant operators to discharge based on more flexible trading behavior. We conclude that novel economic models be combined with tailored implementations of environmental flows. This will allow to find novel solutions for the trade-off between market liberalization and sustainable hydropower development.
... Ultimately, a change in the rules of water abstraction was realized, where media campaigns were instrumental to enhance political awareness (Harwood et al., 2017). Other experiences have also highlighted the need for an action-oriented dialogue among policy makers, water managers, water users and researchers about the necessity and dire consequences of failure to integrate environmental flows and ways of balancing critical trade-offs (Dore, Lebel, & Molle, 2012;Claudia Pahl-Wostl et al., 2013;Richter, 2010). Collaboration and buy-in across all responsible stakeholders has been the main factor in the process of determining and successfully implementing and monitoring environmental flows in different regions of the world such as India, South Africa, China, USA, Mexico where structural decision making was employed in order to create a platform for dialogues in reviewing available information, defining objectives, dealing with uncertainties and trade-offs between competing demands (Harwood et al., 2017;Harwood et al., 2018). ...
... Collaboration and buy-in across all responsible stakeholders has been the main factor in the process of determining and successfully implementing and monitoring environmental flows in different regions of the world such as India, South Africa, China, USA, Mexico where structural decision making was employed in order to create a platform for dialogues in reviewing available information, defining objectives, dealing with uncertainties and trade-offs between competing demands (Harwood et al., 2017;Harwood et al., 2018). Richter (2010) emphasized that fostering an inclusive and transparent stakeholder 74 dialogue is the only way to realize a high degree of satisfaction, and hence sustainability, in water management in general. ...
... Moreover, hydrological EFR methods often set only a minimum discharge boundary, disregarding the potentially adverse effects of flows increasing significantly above natural levels especially in floodplain ecosystems (Hayes et al., 2018;Junk et al., 1989;Schneider et al., 2017;Talbot et al., 2018). Although reviews of EFs have recognised this threat of excessive flows (Acreman et al., 2014;Poff 95 and Zimmerman, 2010;Richter, 2010), no global scale methodology exists yet to quantify it. ...
... The key assumption behind our results is that violating the EFE, either by insufficient or excessive streamflow, is a potential threat to riverine ecosystems. The simple correlation between a discharge proxy variable and ecosystem well-being is, however, a view that has been challenged in the past (Poff and Zimmerman, 2010;Richter, 2010), and the practical allocation of EFs based on insufficient methods has even been argued to potentially cause further degradation of riverine ecosystems Shenton et al., 2012). This is because of the multifaceted biodiversity response to altered flow regimes 380 including variation across spatial scales and distinct parts of the riverine ecosystem, as well as the adaptation of species to flow regime changes over long timespans (Biggs et al., 2005;Poff et al., 1997;Rolls et al., 2018). ...
Preprint
Full-text available
Human actions and climate change have drastically altered river flows across the world, resulting in adverse effects on riverine ecosystems. Environmental flows (EFs) have emerged as a prominent tool for safeguarding riverine ecosystems. However, at the global scale, the assessment of EFs is associated with significant uncertainty. Here, we present a novel method to determine EFs by Environmental Flow Envelopes (EFE), which is an envelope of variability bounded by discharge limits within which riverine ecosystems are not seriously compromised. The EFE is defined globally in approximately 4,400 sub–basins at monthly time resolution, considering also the methodological uncertainties related with global EF studies. In addition to a lower bound of discharge, the EFE introduces an upper bound of discharge, identifying areas where streamflow has increased substantially. Further, instead of only showing whether EFs are violated, as commonly done, we quantify, for the first time, the frequency, severity, and trends of EFE violations, which can be considered as potential threats to riverine ecosystems. We use pre–industrial (1801–1860) quasi-natural discharge and a suite of hydrological EFR methods and global hydrological models to estimate EFE, applying data from the ISIMIP 2b ensemble. We then compare the EFEs to recent past (1976–2005) discharge to assess the violations of the EFE. We found that the EFE violations most commonly manifest themselves by insufficient streamflow during the low flow season, with less violations during intermediate flow season, and only few violations during high flow season. These violations are widespread: discharge in half of the sub–basins of the world has violated the EFE during more than 5 % of the months between 1976 and 2005. The trends in EFE violations have mainly been increasing during the past decades and will likely remain problematic with projected increases in anthropogenic water use and hydroclimatic changes. Indications of excessive streamflow through EFE upper bound violations are relatively scarce and spatially distributed, although signs of increasing trends can be identified and potentially attributed to climate change. While the EFE provides a quick and globally robust way of determining environmental flow allocations at the sub–basin scale, local fine–tuning is necessary for practical applications and further research on the coupling between quantitative discharge and riverine ecosystem responses is required.
... Ultimately, a change in the rules of water abstraction was realized, where media campaigns were instrumental to enhance political awareness (Harwood et al., 2017). Other experiences have also highlighted the need for an action-oriented dialogue among policy makers, water managers, water users and researchers about the necessity and dire consequences of failure to integrate environmental flows and ways of balancing critical trade-offs (Richter, 2010;Dore et al., 2012;Pahl-Wostl et al., 2013). Collaboration and buy-in across all responsible stakeholders has been the main factor in the process of determining and successfully implementing and monitoring environmental flows in different regions of the world such as India, South Africa, China, USA and Mexico where structural decision making was employed in order to create a platform for dialogues in reviewing available information, defining objectives, dealing with uncertainties and trade-offs between competing demands (Harwood et al., 2017;Harwood et al., 2018). ...
... Collaboration and buy-in across all responsible stakeholders has been the main factor in the process of determining and successfully implementing and monitoring environmental flows in different regions of the world such as India, South Africa, China, USA and Mexico where structural decision making was employed in order to create a platform for dialogues in reviewing available information, defining objectives, dealing with uncertainties and trade-offs between competing demands (Harwood et al., 2017;Harwood et al., 2018). Richter (2010) emphasized that fostering an inclusive and transparent stakeholder dialogue is the only way to realize a high degree of satisfaction, and hence sustainability, in water management in general. ...
Article
Environmental flows allocation is an intrinsic part of Integrated Water Resources Management (IWRM). This paper analyses socio‐political issues and effects of environmental flows integration on water availability under the context of increased agricultural intensification in an effort to tackle food insecurity. Lack of appropriate framework comprising the procedural requirements and strategic directions as well as prevalence of politically motivated ad hoc development programmes are among major challenges identified. Introducing environmental flows to a perceived satisfactory level would result in a significant increase of unmet irrigation water demand, yet, “productivity first” norm overtakes. This is presumed to be due to skewed focus on irrigation expansion and low awareness on the possible consequences. The particular challenges highlighted generally unveil the inherent contradictions in the IWRM concept putting its claim that the set of principles and entire course stand universally accepted as a means to balance socio‐economic and environmental outcomes under question.
... Ultimately, a change in the rules of water abstraction was realized, where media campaigns were instrumental to enhance political awareness (Harwood et al., 2017). Other experiences have also highlighted the need for an action-oriented dialogue among policy makers, water managers, water users and researchers about the necessity and dire consequences of failure to integrate environmental flows and ways of balancing critical trade-offs (Dore, Lebel, & Molle, 2012;Claudia Pahl-Wostl et al., 2013;Richter, 2010). Collaboration and buy-in across all responsible stakeholders has been the main factor in the process of determining and successfully implementing and monitoring environmental flows in different regions of the world such as India, South Africa, China, USA, Mexico where structural decision making was employed in order to create a platform for dialogues in reviewing available information, defining objectives, dealing with uncertainties and trade-offs between competing demands (Harwood et al., 2017;Harwood et al., 2018). ...
... Collaboration and buy-in across all responsible stakeholders has been the main factor in the process of determining and successfully implementing and monitoring environmental flows in different regions of the world such as India, South Africa, China, USA, Mexico where structural decision making was employed in order to create a platform for dialogues in reviewing available information, defining objectives, dealing with uncertainties and trade-offs between competing demands (Harwood et al., 2017;Harwood et al., 2018). Richter (2010) emphasized that fostering an inclusive and transparent stakeholder 74 dialogue is the only way to realize a high degree of satisfaction, and hence sustainability, in water management in general. ...
... The allocation of water for environmental purposes is an increasingly active area of river management [2]. However, environmental flows are being implemented in only a small fraction of the world's rivers and in the vast majority of these cases, environmental flow management is focused only on low flows [3]. ...
... There is no (scientifically credible) rule for defining the amount of water that should remain in a river to satisfy environmental flow needs. Decisions about which of the socioeconomic impacts are acceptable, and how much water should remain as environmental flow in a river, involve complex trade-offs among human values and environmental benefits [3]. ...
Article
Full-text available
This article studies the interaction between two environmental objectives actively pursued in water governance. On the one hand, the convenience of establishing or raising a minimum circulating flow in surface water bodies so to improve their quantitative and qualitative status. On the other hand, the need to carry out an intelligent management of aquifers avoiding their overexploitation. In the case study, the proposal consisting of increasing the minimum flow rate on a non-permanent river by means of discharging reclaimed water is studied. Such strategy jeopardizes the recovery of a number of overexploited aquifers since reclaimed water is currently being used for farming under the condition to proportionally reduce groundwater withdrawals. The aim is to discuss whether it is reasonable and rational to ensure continuous flows in water courses which do not have that pattern according to their natural dynamics to the detriment of other environmental or socioeconomic goals. In order to help decision makers to make a right choice, a set of criteria based on legal principles is proposed. According to the principles of minimum intervention, rationality and reasonableness, proportionality, and water economy, it is concluded that the use of reclaimed water to set higher environmental flows in discontinuous and ephemeral streams should only have a minor role in water policies, especially whether it may jeopardize other critical environmental goals.
... Even in these conditions, the hydrological regimes must not be significantly altered in terms of quantity and dynamics. In this sense, the ecological flow was defined for the aim "to protect or restore the integrity and health of river ecosystems (functions and processes)" [4,5]. The recommendations for the computation of ecological flows have been grounded in the relationships among the flow variables and ecological responses to natural flow variability and flow alterations from the natural or historic baseline [6,7]. ...
... It contains the multiannual monthly average discharge (Q m month. a j ) and the multiannual average discharge (Q m a ) as input data for the computation of the monthly ecological flows (Q eco,j ) using Equations (4) and (5). The Q 95% value input in Equation (6) is also mentioned within the table. ...
Article
Full-text available
The overall purpose of the research is to develop a method to compute ecological flows in line with the EU Water Framework Directive (Directive 2000/60/EC) for the whole Romanian territory, for a variety of hydrological, morphological and ecological conditions. The method has three components: a Quantity component, a Dynamic component, and a Real-time operation component. The Quantity component is a hydrological method with elements of the aquatic fauna habitat indirectly linked to biological organisms based on the current Romanian knowledge on the linkages between hydrology and aquatic biology. The Dynamic and Real-time operation components are related to the hydrological forecast. The method is practical, robust and easy to apply. The concept and the ideas use the hydrological forecast to ensure the water dynamics required by the Water Framework Directive, and to develop the quantitative component, keeping in mind that putting it into practice might have importance for a broader audience. In order to better highlight the concept, the paper shows three practical examples of the RoEflow method’s application.
... The flows generated by Q90, 7Q2, and 7Q10 are lower instream flow compared with the Q50 and 25% MAF methods and suggested not to use especially for small streams [44] . Richter et al. (2010) highlighted that used of sustainable boundary approach (SBA) for calculating desired environmental flow outcome will foster sustainable water management [45] . Dong et al. (2012) observed that the modified frequency computation method can be used to calculate optimal ecological flow in complex river system [46] . ...
... The flows generated by Q90, 7Q2, and 7Q10 are lower instream flow compared with the Q50 and 25% MAF methods and suggested not to use especially for small streams [44] . Richter et al. (2010) highlighted that used of sustainable boundary approach (SBA) for calculating desired environmental flow outcome will foster sustainable water management [45] . Dong et al. (2012) observed that the modified frequency computation method can be used to calculate optimal ecological flow in complex river system [46] . ...
Thesis
Full-text available
Ever-increasing population, economic advancement, and climate change have forced to build water conservancy projects such as dam and reservoirs more than ever to secure the water needs and energy needs of the humankind. The water conservancy projects act as a physical barrier in the river system, which limited the flow of the river. As flow regime is of utmost importance in a river system to maintain ecological integrity and health of the riverine ecosystem, those projects have been degrading the health of the riverine ecosystem. The reservoirs facilitate humankind economically and socially. However, the operation of reservoirs gave priority to economic and social benefit and neglected the health of the downstream river ecosystem, which summoned several irreversible impacts on the river ecosystem. Meanwhile, many studies have been done in reservoir operation considering the ecological benefit and concluded that with little improvement and adjustment in the present reservoir operation mode both economic and ecological benefits can be achieved without affecting each other hugely. Therefore, how to optimize the existing operation mode of hydropower station and reservoirs in order to harmonize the trade-off between economic and ecological benefit, which eventually restores the pristine state of the river, and maintain the health of riverine ecosystem achieving maximum comprehensive benefits is the main core of the research. Presently, there is a plethora of research going on ecological dispatching of the reservoir at China and abroad, and many valuable viewpoints and research output have been put forward which strengthen the research on ecological dispatching of the reservoir. Based on those research outputs, firstly the study assesses the degree of hydrologic regime alteration of Erdu River due to Liujiaping hydropower station using histogram comparison approach. Calculation on Hydrologic regime alteration showed the overall alteration value of 80.49% in the severe alteration category. Furthermore, the use of the principal component analysis removed the statistical redundancy involved in the hydrological indicators. The four indicators namely, 3-day minimum, 7-day minimum, 30-day minimum, and high pulse count are suggested as a representative indicator for calculation of the degree of hydrologic regime alteration for the Erdu River. Secondly, the study reviews the ecological flow assessment methodologies. The hydrological method such as an annual distribution method and modified Tennant method is used to calculate monthly minimum flow. The monthly suitable flow is calculated using the month-by-month frequency calculation method. Thirdly, the multi-objective cascade reservoir dispatching model for Liujiaping-Yumitan cascade reservoir is constructed. The maximum economic benefit and minimization of ecological needs in the river for two cases that is a minimum need and suitable need are considered as an objective of the model. The model is solved using NSGA-II algorithm. Moreover, the results provide a set of well distributed optimal solutions along the Pareto front, which is still not enough to make a decision. Finally, the Projection Pursuit Cluster (PPC) model is used for optimal sequencing of the compromise optimal solutions, which has a certain guiding significance for production practice maintaining the health of the river. The analysis results show that the ecological benefits and economic benefits are contradictory, but a reasonable way of dispatching can achieve the maximum comprehensive benefits within a certain range of acceptance. The study has shed light on the impacts of the hydropower station on hydrological regimes of the river by assessing the degree of hydrologic alteration. The study has developed a multi-objective cascade reservoir scheduling model considering the ecological needs and solve the model using NSGA-II algorithm. The results of this study provide guidance for decision makers to improve the comprehensive benefits of the Liujiaping-Yumitan cascade hydropower station along with the protection of the health of the river ecosystem. Keywords: hydrological alteration, histogram comparison approach, principal component analysis, ecological flow, cascade reservoir, non-sorting dominating algorithm, Projection Pursuit.
... Recent policy changes from California's State Water Resources Control Board suggest that environmental flow prioritization, rather than optimization of multi-objectives, is a likely pathway for regulation. Modifying flow regimes to prioritize environmental objectives is commonly viewed as unfeasible because of the cost to other objectives (Richter, 2010;Lessard et al., 2013). However, when environmental flows are designed to achieve specific ecological goals and potentially managed in conjunction with other policy objectives, new opportunities arise (Richter, 2010). ...
... Modifying flow regimes to prioritize environmental objectives is commonly viewed as unfeasible because of the cost to other objectives (Richter, 2010;Lessard et al., 2013). However, when environmental flows are designed to achieve specific ecological goals and potentially managed in conjunction with other policy objectives, new opportunities arise (Richter, 2010). ...
Article
Full-text available
Environmental flow management in watersheds with multi-objective reservoirs is often presented as an additional constraint to an already strained and over-allocated stream system. Nevertheless, environmental flow legislation and regulatory policies are increasingly being developed and implemented globally. In California, USA, recent legislative and regulatory policies place environmental flows at the forefront of the state's water management objectives; however, the increased reliance on hydropower to support climate change mitigation goals may complicate efforts on both issues. This study modelled alternative environmental flow strategies in the major tributaries to the San Joaquin River in California. Strategies included detailed water management rules for hydropower production, flood control, and water deliveries, and three methodological approaches to environmental flow releases: minimum instream flows ("baseline") year-round, 40% of full natural flow (FNF) during the spring runoff season and minimum releases the remainder of the year, and functional flows year-round. Results show that environmental flow strategies affect downstream flow releases in each of the San Joaquin's four sub-basins differently depending on infrastructure capacity, water management objectives, and hydrologic year types. While hydropower production was comparable or declined in the Stanislaus, Tuolumne, and Merced basins, functional flow and 40% FNF strategies increased hydropower production in the Upper San Joaquin basin by 11%. Uncontrolled spill of high flow events decreased when high flow releases were based on hydrologic cues rather than exclusively on flood storage capacity. Water deliveries were reduced in all years regardless of environmental flow strategy. The 40% FNF and functional flow strategies both increased water released to the river relative to baseline, but in different ways. The functional flow strategy allocated water in a holistic approach that enhanced ecological functions in all years, but particularly in moderate and wet years. In contrast, the 40% FNF strategy provided increased flows relative to baseline and some ecological benefit in dry years, but less ecological benefit in other years. This study shows that alternative environmental flow strategies will have different and important trade-offs for integrated water management, and may mutually benefit seemingly conflicting objectives.
... Some refer to ecosystem functions and processes as well. Frequent targets are also ecosystem services offered by free-flowing rivers and maintained through e-flow releases (Auerbach et al., 2014;Richter, 2010). An e-flow regime that restores the integrity and health of a river system will also facilitate the provisioning of social and economic services (e.g., Jorda-Capdevila and Rodríguez-Labajos, 2017) and assist in achieving ecological objectives such as those of the EU Water Framework Directive (EC, 2015). ...
Thesis
Full-text available
Free-flowing rivers support diverse, complex and dynamic ecosystems, as well as provide societal and economic services. Globally, however, the water flow of many rivers has been regulated by hydropower or other sources. Flow modification affects crucial ecosystem functions and processes, and organism’s capacity to fulfil its life cycle requirements. In light of these widespread effects, it is urgent to mitigate ecological impacts caused by existing water infrastructures. To achieve environmental objectives, as well as to manage water uses in a sustainable way, a thorough understanding of ecological responses to hydrological alterations on different temporal levels (e.g., environmental flow, hydropeaking) is essential. This work aims to establish holistic approaches for restoring flows in modified rivers, and to develop environmental flows able to sufficiently mitigate the ecological effects of short-term and annual flow modifications in fluvial ecosystems. This thesis disentangles the effects of multiple stressors and shows that flow regulation is a primary predictor of fish populations. Moreover, by assessing flow-ecology relationships on annual, seasonal, and sub-daily levels, this work identifies fundamental principles to implement flow restoration measures in rivers affected by water abstraction and hydropeaking. While more dynamic flows are generally recommended as environmental flows, flow restrictions are needed for hydropeaking mitigation. Regarding the latter, a seasonal framework for hydrological mitigation based on fish life-history stages is established, and thresholds are synthesized. Overall, this thesis advances the establishment of guidelines for successful flow restoration in river systems affected by competing water uses by establishing holistic flow restoration schemes and by subsuming quantitative and qualitative hydropeaking thresholds. Moreover, this thesis sets the topic of flow restoration into the broader context of hydromorphological river rehabilitation. Hence, this work contributes to a more balanced discussion on trade-offs between societal and environmental water uses.
... However, addressing the challenges of climate change and increasing demand will require a range of strategic actions, including those that directly protect and restore the environment (Pittock and Lankford, 2010;Thompson et al., 2014;Liu, Liu and Yang, 2016;Salik et al., 2016). Failing to adequately incorporate ecosystem values and underestimating the potential cross-scale impacts of water use and climate change on freshwater ecosystems (McCluney et al., 2014) fails to acknowledge the benefits that freshwater systems generate for the wider community (Richter, 2009). ...
Article
Full-text available
A key issue in optimization model development is the selection of spatial and temporal scale representing the system. This study proposes a framework for reasoning about scale in this context, drawing on a review of studies applying multi-objective optimization for water management involving environmental flows. We suggest that scale is determined by the management problem, constrained by data availability, computational, and model capabilities. There is therefore an inherent trade-off between problem perception and available modelling capability, which can either be resolved by obtaining data needed or tailoring analysis to the data available. In the interest of fostering transparency in this trade-off process, this paper outlines phases of model development, associated decisions, and available options, and scale implications of each decision. The problem perception phase collects system information about objectives, limiting conditions, and management options. The problem formulation phase collects and uses data, information, and methods about system structure and behaviour.
... As a result, many countries worldwide have endeavoured to protect river ecosystems after provision has been made for basic human needs (eg Rowlston and Palmer, 2002). However, the implementation of river protection has been problematic (Richter, 2010), because many river courses and flow regimes have been severely altered due to socio-economic development. Previously, river health problems were thought to be only a result of low-flow conditions and therefore, if minimum flows were kept above a critical level, the river's ecosystem would be protected (Poff et al., 1997). ...
Thesis
Full-text available
For effective management of groundwater resources, recharge rates and baseflow volumes need to be quantified to determine sustainable abstraction regimes and to quantify the ecological reserve, the amount of water needed to maintain the natural environment. While a variety of methods have been used to estimate groundwater recharge, estimates vary due to method, temporal and spatial resolution used. In rainfall/runoff modelling where potential recharge is determined by calculating the amount of water that percolates through the unsaturated zone, aquifer components are usually lumped resulting in over or under estimation of recharge. In contrast, groundwater models which include distributive aquifer components are commonly setup to lump climate and surface variables, thereby neglecting seasonal and climatic variability. In this study, a combined rainfall/runoff and groundwater modelling approach was used to determine the net recharge and baseflow in the RAMSAR-listed Verlorenvlei sub-catchment on the west coast of South Africa. This sub- catchment is an important biodiversity hotspot but is also an important agricultural region, hence there is competition for water resources. To understand the water dynamics within the catchment a four-phase approach was taken to determine the baseflow and ecological reserve requirements. This involved firstly, determining the limits of the sub-catchment boundary. Although the Verlorenvlei lake is supported by the Verlorenvlei sub-catchment which is itself fed by four main tributaries (the Hol, Krom Antonies, Kruismans, and Bergvallei), previous research has indicated that only one of these tributaries (the Krom Antonies) played an important role in the delivery of fresh water to the lake system. Initially the catchment boundary was thus modelled on the Krom Antonies tributary, although the understanding gained by the delineation was applied to the entire sub-catchment. To include spatial and temporal variability in groundwater recharge estimates, a rainfall runoff model was used to determine potential recharge using regionalised climate and assumptions regarding aquifer hydraulic conductivity. The potential recharge estimates within the sub-catchment exceeded previous studies (30 % higher), with the daily timestep nature of the J2000 model (Krause, 2001) assumed to account for this difference. To determine whether aquifer hydraulic conductivity could impact groundwater recharge rates, a groundwater model (MODFLOW) was constructed for the main assumed freshwater source of the Verlorenvlei, the Krom Antonies. The groundwater model included distributive aquifer hydraulic conductivity, although the input recharge was lumped which reduced climate seasonality and daily variability. The resultant output from the groundwater model was net recharge (0.3- 11.4 % of rainfall) and average baseflow (14, 000 - 19, 000 m3.d-1), with the model suggesting that the baseflow from the Krom Antonies was not enough to meet evaporation demands (90, 000 m3.d- 1) and that there must be another much larger source. To incorporate daily climatic fluctuations and seasonality in baseflow estimates, the groundwater components of the J2000 were distributed using the net recharge and aquifer hydraulic conductivity from the Krom Antonies. By distributing the groundwater components within the J2000 model, the proportion of interflow to recharge was improved allowing for comprehensive estimates of runoff and baseflow from each tributary. While the model was calibrated using streamflow measurements from the gauging structure on the Kruismans, the measurements were particularly hindered by the DT limit (discharge table) of the station (3.675 m3.s-1), which resulted in reduced confidence in modelling high flow events. To incorporate the limited resolution of the station as well as limited length, an Empirical Mode Decomposition (EMD) was applied to the runoff data and water levels measured at the sub-catchment outlet. The results of the model adaption was that the Krom Antonies was not in fact the main freshwater source, with the Bergvallei supplying the majority of groundwater (49 %) as well as a large contributor of streamflow (29%). While the Hol was initially believed to be a minor contributor, the tributary had the largest ratio of baseflow (0.56), which acted to reduce its flow variability. While the Krom Antonies and Bergvallei is comprised of highly conductive sandstones and quaternary sediments, the Hol which is mainly comprised of shales, resulted in a larger groundwater flow attenuation which reduces its susceptibility to drought and climatic variability. The results of this study highlighted that on average the streamflow (20, 500 m3.d-1) from the feeding tributaries was not able to meet the evaporative demand of the Verlorenvlei and that the lake was mainly supplied by low occurrence high flow events. With the Verlorenvlei under threat due to continued agricultural expansion, it is likely that the lake will dry up more frequently in the future, especially if flows are hampered during wet cycles, when ecosystems regenerate.
... series and ungauged rivers for which regional statistical analyses would be required were not taken into account. Those limits are discussed in Caissie and El-Jabi (1995), Richter (2010), as well as their adaptation to altered flow regimes (Richter et al. 1996;Poff and Zimmerman 2010). The main questions that triggered this hydrological study were: should environmental flow guidelines vary temporally and spatially to improve the management of water withdrawals in Southern Quebec rivers? ...
Article
Faced with increasing demands for water withdrawals and a changing climate, the Quebec Department of Environment and Fight Against Climate Change is reviewing its water withdrawal guidelines to protect riverine ecosystems. For Southern Quebec, guidelines currently limit water withdrawals to a maximum of 15% of the 7Q2 (mean 7-day low flow with a return period of two years) during low flow periods. In this context, one of the issues raised is to investigate measures that help to preserve riverine ecosystems during low flow periods by establishing cut-off flow restrictions. This study compared eight low flow metrics to investigate which can be considered useful metrics to assess environmental flow in Southern Quebec rivers. Using 98 hydrometrics stations with a minimum of 20 years of daily flow data from eight hydrological regions, those low flow metrics were compared to three thresholds based on Tennant Method for monthly and annual temporal scales. The relevance of current hydrological regions delineation was investigated by looking at results within these regions, compared to six groups of stations defined using multivariate analyses. This study emphasizes that assessing environmental flows is linked to the hydrological context of the area of interest, the temporal scale of the historical data available, and the catchment size. The results showed that (1) winter low flows were lower than summer low flows; (2) 23% to 26% of the values were under the conservative thresholds for all the metrics depending of the time scale; and (3) the 7Q2, 7Q10 (mean 7-day low flow with a return period of ten years), Q95 and Q90 (95th and 90th percentile on the flow duration curve) are the less conservative for rivers having a low regime flow. To conclude, assessing several regionally adapted environmental flow metrics is recommended rather than systematically using the 7Q2 for Southern Quebec.
... Second, in river basins where e-flows policies may be appropriate, what socio-political barriers constrain their implementation? The main obstacles to successful e-flows implementation are largely socio-political (Pahl-Wostl et al. 2013;Le Quesne et al. 2010;Richter 2010;Horne et al. 2017aHorne et al. , 2017bMezger et al. 2019). These include a lack of communication, support, and political will among stakeholders; insufficient funds, capacity, and expertise; and institutional and regulatory mandates that present conflicts of interest (Moore 2004;Hirji and Davis 2009;Opperman et al. 2018). ...
Article
Policies that mandate environmental flows (e-flows) can be powerful tools for freshwater conservation, but implementation of these policies faces many hurdles. To better understand these challenges, we explored two key questions: (1) What additional data are needed to implement e-flows? and (2) What are the major socio-political barriers to implementing e-flows? We surveyed water and natural resource decision makers in the semi-arid Red River basin, Texas-Oklahoma, USA, and used social network analysis to analyze their communication patterns. Most respondents agreed that e-flows can provide important benefits and identified the same data needs. However, respondents sharply in their beliefs on other issues, and a clustering analysis revealed two distinct groups of decision makers. One cluster of decision makers tended to be bearish, or pessimistic, and believed that: current flow conditions are not adequate, there are many serious socio-political barriers to implementation, water conflicts will likely increase in the future, and climate change is likely to exacerbate these issues. The other cluster of respondents was bullish, or optimistic: they foresaw fewer future water conflicts and fewer socio-political barriers to implementation. Despite these differences, both clusters largely identified the same data needs and barriers to e-flows implementation. Our social network analysis revealed that the frequency of communication between clusters was not significantly different than the frequency of communication within clusters. Overall, our results suggest that the different perspectives of decision-makers could complicate efforts to implement e-flows and proactively plan for climate change. However, there are opportunities for collaboration on addressing common data needs and barriers to implementation. Overall, our study provides a key socio-environmental perspective on e-flows implementation from a semi-arid and socio-politically complex river basin and contextualizes the many challenges facing e-flows implementation in river basins globally.
... The concept of EFlows evolved from a growing global concern over degrading rivers and estuaries and a need to mitigate the effects of human development by managing water resources for long-term sustainability (Richter, 2009 Western Indian Ocean Ecosystem Guidelines and Toolkits mate change. The ecosystems can then continue to provide ecosystem services of value to people into the future (Figure 2). ...
Book
Full-text available
These Guidelines for the Assessment of Environmental Flows (EFlows) in the Western Indian Ocean (WIO) region form part of the deliverable for the project entitled Implementation of the Strategic Action Programme for the protection of the WIO from land-based sources and activities (WIOSAP). The Project is being implemented and executed through a Partnership Approach, with the United Nations Environmental Programme (UNEP) Nairobi Convention Secretariat as the Executing Agency. The participating countries include Comoros, Madagascar, Mauritius, Seychelles, Mozambique, Kenya, Tanzania, France, Somalia and South Africa. The goal of WIOSAP is to: ‘Improve and maintain the environmental health of the region’s coastal and marine ecosystems through improved management of land-based stresses’. The specific objective of WIOSAP is: ‘To reduce impacts from land-based sources and activities and sustainably manage critical coastal-riverine ecosystems through the implementation of the WIOSAP priorities with the support of partnerships at national and regional levels.’ There are four components to the Project: 1. Protection, restoration and management of critical coastal habitats and ecosystems; 2. Improvement of water quality; 3. Sustainable management of river flows, including building capacity for EFlows Assessments and implementation; and 4. Strengthening governance and awareness. This document Guidelines for the Assessment of EFlows in the WIO region is part of the activities of Component 3.
... The effect on a river system is mainly caused by the construction of various water conservancy projects. At present, more than 50,000 dams (heights greater than 15 m) exist worldwide (Lehner et al., 2011), which regulate the natural variability of the runoffs, leading to a change in the natural flow regime (Richter, 2010;Poff and Schmidt, 2016;Arthington et al., 2018;Liu et al., 2018;Li et al., 2020). For runoffs under regulated conditions and induced by climatic forces, time sequences cannot be accurately predicted and typically present statistical non-stationarity (Serinaldi and Kilsby, 2015;Poff, 2018;Ali et al., 2020b;Huang et al., 2020). ...
Article
Clearly, water conservancy projects are advantageous for human beings; however, they significantly change the streamflow variability of rivers. This change is a result of the complex and non-linear interactions between natural processes and human activities. Thus far, our understanding of these interactions is still inadequate. In this study, these interactions were evaluated for a large river basin (i.e. the Pearl River basin) with numerous reservoirs to identify reservoir operation scenarios for mitigating drought and flood impacts. To this end, first, the flow variability pattern was derived based on the concept of the admissible range of flow variability. Second, the moving average over shifting horizon method was used to evaluate the effects of the reservoirs on the streamflow variability. Finally, the network theory and data mining technology were applied to establish the streamflow relations between the upstream and downstream reservoirs. The results show that the cascade reservoirs reshape the streamflow variability patterns of the Pearl River in time and space and have a cumulative effect on the downstream runoff. The constructed networks and the identified operation scenarios present that this effect is mainly influenced by the upstream critical reservoirs having different inflows and storage capacities. This suggests the varied roles of the reservoirs for drought mitigation and flood control limiting the formulation and application of integrated operating strategies for the multi-reservoir system.
... [4]), 20% of the flow can be considered appropriate for withdrawal purposes (Richter, 2010;Richter et al., 2012;Veettil and Mishra, 2016). ...
... In addition to human water demands, environmental flow requirements (EFRs) maintaining the health of river ecosystem is also a key component in water scarcity assessment (Smakhtin et al 2004). However, EFRs often conflict with anthropological water use (Richter 2010, Pastor et al 2019, and the fulfillment of EFRs may impose large restrictions on the human appropriation of water resources from rivers , Hanasaki et al 2013, Wada et al 2016. EFRs are necessary for the calculation of the Sustainable Development Goal 6.4.2 indicator of water stress (FAO 2019). ...
Article
Full-text available
The inclusion of environmental flow requirements (EFRs) in global water scarcity assessments is essential to obtain a reasonable representation of the water scarcity status. However, at a global scale, the quantification of EFRs is subject to large uncertainties resulting from various methods. So far, it is unclear to what extent the uncertainties in EFRs affect global water scarcity assessments. In this study, we examined the differences between EFR estimation methods and quantified their effects on spatially explicit water scarcity assessments, based on reconstructed global water withdrawal data and naturalized streamflow simulations. The global mean EFRs estimated by different methods ranged from 129 m3/s to 572 m3/s. Consequently, with the fulfillment of the EFRs, the area under water scarcity ranged between 8 % and 52 % of the total global land area, and the affected population ranged between 28 % and 60 % of the total population. In India and Northern China, 44–66 % and 22–58 % of the country's land area, respectively, is affected by water scarcity; this percentage is higher than that found in other countries. The effects of different EFRs on water scarcity assessment are large in many regions, but relatively small in regions that experience intensive water use due to anthropological activities (such as Northern China and India). Through this study, we have put forth the need for the reconciliation of the estimates of EFRs to produce more reasonable and consistent water scarcity assessments.
... From 2010 until today, novel research is undertaken to move beyond the original concept of e-flows. As initial studies linked the concept of e-flows with the magnitude and timing of flow releases from dams by estimating the minimum amount of water that is left in rivers and sustains their natural riparian and hydromorphological features (Acreman, Arthington, et al., 2014;Poff et al., 2016;Richter & Thomas, 2007), numerous methods have emerged that attempt to assess the environmental water requirements by allocating the flow components in a manner that maintains the ecosystem functionality (Poff & Matthews, 2013;Richter, 2010). Depending on whether the method uses strictly hydrologic data, or hydraulic and habitat information or a more complete set of river components, including societal uses, e-flow methods can be categorized as hydrological, hydraulic/ habitat, and holistic [Directorate-General for Environment (European Commission), 2015] (Table 5.1). ...
... In comparison to the baseline, the adjustment of the frequency factors of occurrence is a significant improvement to the model because eflow implementation through water allocation systems (EWR) secures both high and low flow events in the short and long term, without underestimating such components in intermittent rivers and ephemeral streams, which are more dependent on wet conditions than perennial rivers [3,7,8,18,24,[33][34][35][36][37]40,41]. By examining river sites per streamflow type, common patterns with significant differences arise at a hydrological level [23,33]. ...
Article
Full-text available
Environmental flow (eflow) reference values play a key role in environmental water science and practice. In Mexico, eflow assessments are set by a norm in which the frequency of occurrence is the managing factor to integrate inter-annual and seasonal flow variability components into environmental water reserves. However, the frequency parameters have been used indistinctively between streamflow types. In this study, flow variability contributions in 40 rivers were evaluated based on hydrology, climate, and geography. Multivariate assessments were conducted based on a standardized contribution index for the river types grouping (principal components) and significant differences (one-way PERMANOVA). Eflow requirements for water allocation were calculated for different management objectives according to the frequency-of-occurrence baseline and an adjustment to reflect the differences between river types. Results reveal that there are significant differences in the flow variability between hydrological conditions and streamflow types (p-values < 0.05). The performance assessment reveals that the new frequency of occurrence delivers climate-smart reference values at least at an acceptable level (for 85–87% of the cases, r2 ≥ 0.8, slope ≤ 3.1), strengthening eflow assessments and implementations.
... These EF methods were mainly developed at river or basin scale, either in the context of flow restoration projects (Richter, Warner et al. 2006) or for assessing the ecological status of rivers at a regional, national, or continental level, as per, for instance, the Water Framework Directive 2000/60/EC (Council 2000). (Tennant 1976, Tessmann 1980, Richter, Baumgartner et al. 1997, Armstrong, Todd et al. 1999, Smakhtin, Shilpakar et al. 2006, Richter 2010, Babel, Dinh et al. 2012 Hydraulic Flow velocity, river crossing area R2Cross method (Armstrong, Todd et al. 1999) Habitatsimulation Flow velocity, river cross section, dataset of a fish specie PHABSIM, IFIM (Bovee 1986, Bovee, Lamb et al. 1998, Milhous 1999, Capra, Sabaton et al. 2003 (King and Louw 1998, Hughes 2001, Bunn and Arthington 2002, Arthington, Bunn et al. 2006) ...
Thesis
Freshwater ecosystems are among the most threatened ecosystems on Earth. At the same time, water demand for food is projected to increase with projected increase in population and diet shift putting part of the population under pressure in terms of food security. These projections are likely to be exacerbated by climate change. Over the past decades, irrigated areas have nearly tripled to meet actual human food requirements. Today, 40% of food production comes from irrigated production and about 30% from irrigated areas. This increasing share of irrigated production has come at the expense of freshwater ecosystems and river health. About half of the rivers have been fragmented and altered via the constructions of dams and reservoirs and via diversion of river flow to irrigated fields. Furthermore, water demand for industry, household and hydropower is predicted to increase and competition between water sectors will intensify. Under actual water competition, water availability for freshwater ecosystems has often been neglected.Over the past decade, awareness was given to define planetary boundaries for natural resources especially freshwater ones. While irrigation withdrawals and industries and household withdrawals already reach respectively about 2600 km3 yr-1 and 1000 km3 yr-1, planetary boundaries for freshwater have been defined to 4000 km3 yr-1. With the expected rise in water demand for food and industries, freshwater boundaries are likely to be exceeded in the coming decades and it is urgent to define global water availability and demand with accurate time and spatial resolutions. More specifically, it is necessary to develop a method that enables the calculation of water demand for freshwater ecosystems known as “Environment Flow Requirements” (EFRs). EFRs were often neglected in global assessments and/or defined with annual proxies.The overall objectives of this thesis were to redefine global water demand for freshwater ecosystems (EFRs) and set these last as a priority in global integrated assessments. For that, it was necessary to design a robust methodology that can be easily implemented in Global Hydrological Models (GHMs) and in global integrated assessments. In chapter 2, existing global and local Environmental Flow (EF) methods were reviewed. Three methods were selected among existing global methods, including the Smakhtin method, which is based on a combination of annual quantiles and proxies of annual flow, the Tennant method, which is based on annual proxies of flow, and the Tessman method, which is based on monthly proxies of flow. Two other methods were designed for this study: the Variable Monthly Flow (VMF) method, which is based on the allocation of the percentage of monthly flow to the environment and the Q90_Q50 method, which is based on the allocation of flow quantiles. These methods were compared with 11 local case studies from different ecoregions, for which EFRs have been defined locally with ecological and hydrological data collection. The VMF method showed the best performance against local case studies and demonstrated easiness of use and validation with different flow regime types. Among the five global EF methods, EFRs represent 20 to 50% of mean annual flow to maintain EFRs in “fair” ecological conditions.In chapter 3, the concept of “Environmental Flow (EF) deficit” was designed. It represents the lacking flow to meet EFRs. EF deficit was defined on a monthly basis at 0.5 deg. The originality of this study is that the origin of the deficit was characterized by the natural deficit and the anthropogenic deficit. Natural deficit is defined when EFRs are not met due to natural climate variability and anthropogenic deficit is defined when EFRs are not met due to water extractions for irrigation or other users. The frequency, timing and magnitude of each deficit were also calculated at global scale. The EF deficit was also studied for 23 river basins, which are located in different ecoregions, and it was shown that flow regime type, origin of deficit, magnitude of deficit and level of flow alteration were correlated. Perennial rivers such as the Congo River showed only natural deficit while very altered river such as the Godavari river showed high respective natural and anthropogenic deficit. In chapter 4, we set EFRs as a priority user in the global vegetation model LPJmL. It was shown that to sustain EFRs in “fair” ecological conditions, irrigation water use should be reduced by 30%, which would lead to 30% less food coming from irrigated area and a total of 5% loss in food production. Calorie loss per capita was really high in developing countries where population density is high such as in South-East Asia. This loss in food production can however be compensated by an increase of 50% in irrigation use efficiency.In chapter 5, we used an economic optimization model (GLOBIOM) to study future global change including different constrains of EFRs. It was shown that, under future climate change (RCP 8.5) and socio-economic development (SSP2), international trade should be increased by 15% to compensate for EFRs implementations compared to a business-as-usual scenario. The positive outcome is that it was demonstrated that food and water security for humans and ecosystems can be sustained with three levees: use of trade (+15%), conversion of irrigated land to rainfed land (60Mha) in South Asia and expansion of rainfed land into natural area in Latin America.In the chapter 6, we reviewed and analyzed each chapter as an ensemble. The new development of the VMF method is acknowledged thanks to its application in all chapters of this thesis and in many other global assessments. Among them, two studies redefined the freshwater planetary boundaries at 2,800 km3 yr-1 which is lower than previous estimates defined by Rockstrom et al. (2009). This thesis allowed the inclusion of EFRs in global integrated assessments with refined temporal and spatial scales and water demand for ecosystems are now recognized and acknowledged. The limitations of the VMF method are also discussed such as its weakness to be compatible with inter-annual studies considering extreme events such as floods and droughts. Further data collection on eco-hydrological relationships should be organized and harmonized at global scale to further improve EFRs at global scale. Characterization of EF deficit with differentiation of the anthropogenic and natural deficit can be used as a tool to prioritise actions in terms of river restoration/protection. In face of meeting future SDGs, we highlighted the complexity in meeting food and water security for humans and ecosystems. Competition between different water sectors already exist and require local, regional and international consensus to satisfy all water users while safeguarding water availability for freshwater ecosystems. For that, future improvement in agriculture and water management is fundamental to provide future sustainable water access to humanity.
... It is challenging because the interaction between a species' population dynamics and river flows are not well-understood in many regions of the world (Robins et al. 2005;Costa et al. 2007). Additionally, changes in river flows are often managed within the jurisdiction of catchment managers and hydrologists (Richter 2010). Allocations of water for use by industries downstream, such as coastal fisheries, may not be prioritised in the planning process (Poff et al. 2003). ...
Article
Full-text available
Around 36,000 km³ of freshwater flows through rivers and estuarine ecosystems and enter the world’s coastal fishing regions every year. The flow of freshwater and sediments creates regional changes in coastal circulation, stimulates marine productivity and helps define the hydrologic properties of estuarine and oceanic waters. These processes can affect different life stages of marine species either directly, through variations in salinity and temperature, or indirectly, due to changes in the availability of food and habitat. This paper reviews the relationship between freshwater flowing through estuarine and coastal ecosystems, and the variable productivity associated with global marine capture fisheries. The results of a global synthesis revealed that 72% of species representing 77% of the total catch (43 million tonnes) were linked to river flows for at least some part of their life cycle. Insights into how the relationship between flow and fishery production varies globally indicates wild capture fisheries and freshwater resources would benefit from an integrated planning and management approach.
... Sustainability management of short-lived iteroparous fish species in habitats periodically subject to flow intermittence depends on limiting out-of-channel uses of water (Richter et al., 2003) in ways that result in relatively robust rates of fish population growth and that incorporate consideration for financial, hydrologic, technical, and legal constraints that are inherent in contemporary water resource management Richter, 2010;Poff et al., 2010;. Selection of effective management strategies requires an interdisciplinary and integrated assessment (Arthington, 2021) to discover the mix of management elements that best address the plurality of needs (Oldekop et al., 2016) of the aquatic biota, in addition to the needs of water users that deplete or impair river ecosystems. ...
Article
Human perturbations affect many aquatic ecosystems globally. We use age‐structured matrix population models to explore how population growth rates in short‐lived freshwater fish are affected by recurrent environmental perturbations to river ecosystems. Simulations are summarized to reveal how species‐specific fitness characteristics contribute to population sustainability in habitats subject to recurrent perturbation. Deterministic calculations are used to estimate time to population recovery with successive years of intermittence disturbance, followed by post‐perturbation equilibrium conditions. Perturbation that reduces only juvenile survival has a shorter recovery time to initial population size and greater resilience of population growth than when adult survival is reduced. Consecutive occurrences of perturbation lengthen recovery time nonlinearly, more notably when adults experience perturbation mortality. We illustrate with an example how managers could identify multiple options to mitigate recurrent ecosystem perturbations by reducing perturbation frequency and/or mitigating perturbation mortality. Our simulations suggest parameter approximations for a hypothetical species provide a useful frame of reference for river restoration and conservation when life history data are lacking for a specific species of concern. This article is protected by copyright. All rights reserved.
... Maintaining this full spectrum of naturally occurring fl ows and their inherent pattern of variability in a river (or other water body) is, however, often not feasible given the various competing sectoral demands associated with water resources development (for domestic supply, irrigation, fl ood control, hydropower, navigation, etc.), as well as changes in catchment land use and climate. With increasing alteration of the water fl ow regime from its natural pattern comes increasing ecological risk (Richter, 2009;Poff et al., 2010). Hence, the higher the level and degree of assurance of ecosystem health and delivery of ecosystem services that are required, the more water will need to be reserved or allocated -as part of water resources planning -for maintaining ecosystem condition, and the more the system's fl ow magnitude, timing and pattern of variability will need to be preserved. ...
Book
Full-text available
The integrated, effi cient, equitable and sustainable management of water resources is of vital importance for securing ecosystem health and services to people, not least of which is food production. The challenges related to increasing water scarcity and ecosystem degradation, and the added complexities of climate change, highlight the need for countries to carefully manage their surface water and groundwater resources. Built upon the principles of economic effi ciency, equity and environmental sustainability, integrated water resources management (IWRM) can be shaped by local needs to maximize allocative effi ciency and better manage water for people, food, nature and industry. However, the fl exibility of the approach means that it is interpreted and applied in ways that prioritize and address immediate challenges created by demographic, economic and social drivers, often at the expense of environmental sustainability – and hence also of long-term food security. The need to more explicitly include ecosystems in water management practices and safeguard long-term food security can be addressed partly by refi ning the notion of ‘water for food’ in IWRM as ‘water for agroecosystems’. This would also serve to eliminate much of the current dichotomy between ‘water for food’ and ‘water for nature’, and deliver a more balanced approach to ecosystem services that explicitly considers the value and benefi ts to people of a healthy resource base. The adoption of an ecosystem services approach to IWRM, and incorporation of environmental fl ows as a key element, can contribute to long-term food security and ecosystem health by ensuring more effi cient and effective management of water for agroecosystems, natural systems and all its other uses.
... Therefore, EFR has a significant role in quantifying the accurate level of blue water scarcity of a region. Although different methodologies (e.g., low streamflow method, Adapted Smakhtin methodology) are developed to evaluate EFR, the presumptive standard method developed by Richter (2010), Richter et al. (2012) is widely used (Liang et al., 2021;Veettil and Mishra, 2018;Zeng et al., 2012). According to the presumptive standard method, water withdrawal from streamflow greater than 20% will cause degradation in ecosystem health, and this available water for withdrawal is termed blue water availability (Veettil and Mishra, 2016). ...
Article
Full-text available
Over the last four decades, water security assessment has attracted much political and economic attention. An improved understanding of the relationships between water demand and supply is needed to mitigate the impacts of diminishing water resources. This study provides an overview of water security assessment by focusing on the various water security indicators and the concept of water footprint (blue, green, and grey water). The water security indicators based on the water footprint concept is currently receiving more attention because it accounts for the return flow from the total water withdrawn from a watershed. We also investigate the application of different physically-based hydrological models, such as Soil and Water Assessment Tool (SWAT) and Variable Infiltration Capacity (VIC), on water security assessment at a regional to continental scale. However, hydrological/agricultural system models cannot quantify evapotranspiration from irrigation and rainwater separately. Therefore, independent quantification of blue and green water footprint from the irrigated field is challenging. For illustration purposes, we apply the fully distributed Agricultural Ecosystems Services (AgES) model in the Big Dry Creek Watershed (BDCW), an intensively managed and irrigated watershed located in semiarid Colorado. The results indicate that the blue water footprint is higher than the green water footprint in the watershed. In addition, the spatial distribution of grey water footprint is highly correlated with the amount of fertilizer application. The variation of grey water footprint in the irrigated fields is higher than blue and green water footprints. We conclude that applying a physically distributed model can provide useful insight into the impact of climate and anthropogenic activities on water security at different scales.
... In order to overcome these general issues, research and monitoring of e-flows' adjustments is often required (Richter, 2009;Zang et al., 2012), as well as, the synthesizing of knowledge and experience gained from individual case studies (Arthington et al., 2004;. In fact, regional and local approaches have a fundamental role in the understanding e-flow methods limitations. ...
Article
Full-text available
River ecosystems are characterised by a naturally high level of hydrodynamic perturbations which create aquatic-terrestrial habitats indispensable for many species, as well as for the human beings' welfare. Environmental degradation and habitat loss caused by increasing anthropogenic pressures and global change affect freshwater aquatic ecosystems worldwide and have caused changes in water flow regimes and channels morphologies. These, in turn, decreased the natural flow capacity and reduced habitat availability, thus causing severe degradation of rivers' ecological integrity. The ecological flow (e-flow) is commonly intended as the quantity, timing, duration, frequency and quality of water flows required to sustain freshwater, estuarine and near‐shore ecosystems and the human livelihoods and well‐being. Maintaining the e-flow represents a potential tool for restoring and managing river ecosystems, to preserve the autochthonous living communities, along with environmental services and cultural/societal values. In the last decade, methods for the determination of the e-flow in European rivers moved from a simply hydrological approach towards establishing a linkage between the hydrological regime and the good ecological status (GES) of the water bodies, as identified by the European Water Framework Directive (WFD; 2000/60/EC). Each Member State is required to implement and integrate into the River Basin Management Plans (RBMP) a methodology for the determination of the e-flow, ensuring that rivers can achieve and maintain the GES. The competent river basin authorities have thus to ascertain whether national methodologies to can be applied to different river typologies and basin environment characteristics. In this context, we narratively review the e-flow assessments in the heterogeneous Italian territory, in particular on a water scant region such as Sardinia, by analysing laws, guidelines and focusing on study cases conducted with micro and meso-scale hydraulic-habitat approaches. In the sight of a more ecological-based application of national e-flow policy, we suggest that meso-habitat methods provide a valuable tool to overcome several limitations of current e-flow implementation in the Italian territory. However, to face future challenges, such as climate change adaptation, we stress the need for further experimental studies to update water management plans with greater attention for nature conservation.
... Because of the limited ability for water to be allocated for environmental purposes in water-limited systems, leveraging the presence of threatened or endangered species or ecosystems often is the only legal and regulatory pathway for allocating water for e-flows (Harwood et al., 2018;Richter, 2010). In the US, for example, the Endangered Species Act (ESA) is the only authority or mechanism to implement e-flows. ...
Article
Full-text available
Environmental flows (e‐flows) are powerful tools for sustaining freshwater biodiversity and ecosystem services, but their widespread implementation faces numerous social, political, and economic barriers. These barriers are amplified in water‐limited systems where strong trade‐offs exist between human water needs and freshwater ecosystem protection. We synthesize the complex, multidisciplinary challenges that exist in these systems to help identify targeted solutions to accelerate the adoption and implementation of environmental flows initiatives. We present case studies from three water‐limited systems in North America and synthesize the major barriers to implementing environmental flows. We identify four common barriers: (a) lack of authority to implement e‐flows in water governance structures, (b) fragmented water governance in transboundary water systems, (c) declining water availability and increasing variability under climate change, and (d) lack of consideration of non‐biophysical factors. We then formulate actionable recommendations for decision makers facing these barriers when working towards implementing environmental flows: (a) modify or establish a water governance framework to recognize or allow e‐flows, (b) strive for collaboration across political jurisdictions and social, economic, and environmental sectors, and (c) manage adaptively for climate change in e‐flows planning and recommendations. This article is categorized under: Water and Life > Conservation, Management, and Awareness Human Water > Water Governance Engineering Water > Planning Water Water‐limited systems around the world face numerous barriers to implementing environmental flows (e‐flows) despite calls to accelerate their implementation to curb freshwater biodiversity declines. In this article, we synthesize these barriers and develop actionable recommendations based on case studies in the south‐central United States and northern Mexico.
... From 2010 until today, novel research is undertaken to move beyond the original concept of e-flows. As initial studies linked the concept of e-flows with the magnitude and timing of flow releases from dams by estimating the minimum amount of water that is left in rivers and sustains their natural riparian and hydromorphological features (Acreman, Arthington, et al., 2014;Acreman, Overton, et al., 2014;Poff et al., 2016;Richter & Thomas, 2007), numerous methods have emerged that attempt to assess the environmental water requirements by allocating the flow components in a manner that maintains the ecosystem functionality (Poff & Matthews, 2013;Richter, 2010). Depending on whether the method uses strictly hydrologic data, or hydraulic and habitat information or a more complete set of river components, including societal uses, e-flow methods can be categorized as hydrological, hydraulic/ habitat, and holistic [Directorate-General for Environment (European Commission), 2015] ( includes studies that attempt to estimate the minimum flow that is vital to sustain the population of key aquatic biota (e.g., fish or benthic invertebrates) or to maintain the riparian vegetation, floodplains, and wetlands (Baumgartner et al., 2014;King et al., 2016;Lytle et al., 2017;Rivaes et al., 2017). ...
... Many challenges have been met by efforts to incorporate environmental flows. A system of prioritization among water uses involves many water allocation systems that either do not favor environmental flow conservation, or do not allow for ecological protection from high flow events [49]. Major progress in environmental flow management has been made in recent years because of various factors, including government dedication to environmental flow projects, increases in scientific expertise, and processes for evaluation which involve greater stakeholder collaboration and co-design. ...
Article
Full-text available
This study aims to develop a reservoir operation rule adding downstream environmental flow release (EFR) to the exclusive use of irrigation water supply (IWS) from agricultural reservoirs through canals to rice paddy areas. A reservoir operation option was added in the Soil and Water Assessment Tool (SWAT) to handle both EFR and IWS. For a 366.5 km2 watershed including three agricultural reservoirs and a rice paddy irrigation area of 4744.7 ha, the SWAT was calibrated and validated using 21 years (1998–2018) of daily reservoir water levels and downstream flow data at Gongdo (GD) station. For reservoir water level and streamflow, the average root means square error (RMSE) ranged from 19.70 mm to 19.54 mm, and the coefficient of determination (R2) and Nash–Sutcliffe efficiency (NSE) had no effect on the improved SWAT. By applying the new reservoir option, the EFR amount for a day was controlled by keeping the reservoir water level up in order to ensure that the IWS was definitely satisfied in any case. The downstream mean wet streamflow (Q95) decreased to 5.70 m3/sec from 5.71 m3/sec and the mean minimum flow (Q355) increased to 1.05 m3/sec from 0.94 m3/sec. Through the development of a SWAT reservoir operation module that satisfies multiple water supply needs such as IWR and EFR, it is possible to manage agricultural water in the irrigation period and control the environmental flow in non-irrigation periods. This study provides useful information to evaluate and understand the future impacts of various changes in climate and environmental flows at other sites.
... These conservative thresholds clarify manager's interest of carrying out comprehensive hydrological, geographical and biological studies to estimate them. In addition, minimum and maximum flow thresholds can be used to provide a range of possible environmental flows as the sustainability boundaries proposed by Richter (2009) or the presumptive standards method (Richter et al. 2012). However, the assessment of flow thresholds is a huge task rendered more difficult because of the paucity of ecological information to match with the definition of environmental flow. ...
Article
Full-text available
Through a case study in Southern Quebec (Canada), the assessment of environmental flows in light of the effects of climate change is investigated. Currently, the 7Q2 flow metric (7-day average flow with a 2-year return period) is used for water abstraction management. Several flow metrics were calculated using flow time series simulated by a deterministic hydrological model (HYDROTEL) and climate change scenarios as inputs. Results were compared within homogeneous low flow regions defined using ascendant hierarchical clustering, for the 1990, 2020 and 2050 horizons and annual, summer and winter periods. The impact of each flow metric on the potential availability of physical habitat was analyzed using the wetted perimeter as a proxy. Results indicated that: (1) the increasing non-stationarity of simulated flow data sets over time will complicate the use of frequency analysis to calculate the 7Q2 flow metric; (2) summer low flow values are expected to be lower than winter low flows; and (3) flow-duration curve metrics like the LQ50 (median discharge value of the month with the lowest flow) may become relevant environmental flow metrics by 2050. Results question current water abstraction management tools and permit us to anticipate future local and regional issues during low flow periods. HIGHLIGHTS This is an environmental flow (EF) study considering climate change effects in Southern Quebec rivers.; Two flow thresholds and a wetted perimeter threshold were used, both theoretical, to compare the results and their impact on how river ecosystems protection may evolve.; Low flow regions defined using multivariate analyses reveal the evolution of low flows between 1990 and 2050 horizons and identified local issues.; Frequency analysis is not recommended for EF assessment in the future, due to the increasing non-stationarity of flow time series with climate change effects.; Water managers should consider adjusting EF approaches to account for climate change effects on low flows in Southern Quebec rivers.;
... From 2010 until today, novel research is undertaken to move beyond the original concept of e-flows. As initial studies linked the concept of e-flows with the magnitude and timing of flow releases from dams by estimating the minimum amount of water that is left in rivers and sustains their natural riparian and hydromorphological features (Acreman, Arthington, et al., 2014;Acreman, Overton, et al., 2014;Poff et al., 2016;Richter & Thomas, 2007), numerous methods have emerged that attempt to assess the environmental water requirements by allocating the flow components in a manner that maintains the ecosystem functionality (Poff & Matthews, 2013;Richter, 2010). Depending on whether the method uses strictly hydrologic data, or hydraulic and habitat information or a more complete set of river components, including societal uses, e-flow methods can be categorized as hydrological, hydraulic/ habitat, and holistic [Directorate-General for Environment (European Commission), 2015] ( includes studies that attempt to estimate the minimum flow that is vital to sustain the population of key aquatic biota (e.g., fish or benthic invertebrates) or to maintain the riparian vegetation, floodplains, and wetlands (Baumgartner et al., 2014;King et al., 2016;Lytle et al., 2017;Rivaes et al., 2017). ...
Chapter
Mountains and mountain rivers provide a multitude of invaluable goods and services to a profound portion of the planet’s population. As “water towers” of the Earth mountains are sources of the mightiest world rivers and play a pivotal role for global biodiversity, freshwater, and sediment supply. Distinct morphological, climatic, hydrological, hydrochemical, and biological features of mountainous river ecosystems, compared to lowland ones, make them particularly fragile and vulnerable to human interference. Despite a number of remote mountain areas and rivers still remaining intact from direct human pressures, the majority of mountain ecosystems, are being increasingly threatened by adverse local and global changes driven by market economy. To efficiently conserve and sustainably use mountain ecosystems and contribute to the survival of the planet, it is critical to change our standards and life attitudes by realizing and appreciating our immediate connection to the global ecosystem, change attitudes and current consumption patterns, and stimulate the ways our global society functions and interacts with the natural environment.
... From 2010 until today, novel research is undertaken to move beyond the original concept of e-flows. As initial studies linked the concept of e-flows with the magnitude and timing of flow releases from dams by estimating the minimum amount of water that is left in rivers and sustains their natural riparian and hydromorphological features (Acreman, Arthington, et al., 2014;Acreman, Overton, et al., 2014;Poff et al., 2016;Richter & Thomas, 2007), numerous methods have emerged that attempt to assess the environmental water requirements by allocating the flow components in a manner that maintains the ecosystem functionality (Poff & Matthews, 2013;Richter, 2010). Depending on whether the method uses strictly hydrologic data, or hydraulic and habitat information or a more complete set of river components, including societal uses, e-flow methods can be categorized as hydrological, hydraulic/ habitat, and holistic [Directorate-General for Environment (European Commission), 2015] ( includes studies that attempt to estimate the minimum flow that is vital to sustain the population of key aquatic biota (e.g., fish or benthic invertebrates) or to maintain the riparian vegetation, floodplains, and wetlands (Baumgartner et al., 2014;King et al., 2016;Lytle et al., 2017;Rivaes et al., 2017). ...
Chapter
The modification of sediment and flow regimes caused by damming and river regulation has deleterious effects on the ecological and morphological river processes. This alteration of river systems triggered the implementation of safeguarding environmental flows (e-flows) defined as “the quantity, timing, and quality of water flows required to sustain freshwater and estuarine ecosystems and the human livelihoods and wellbeing that depend on these ecosystems”. In the last decades, physical habitat simulation approaches emerged as fundamental stand-alone or supplementary methods for e-flow assessment. These approaches combine three main components: (1) hydraulic simulation, (2) habitat suitability modeling, to determine the quality of the available habitat, and (3) hydrological analyses (under current and climate change scenarios). E-flow regimes are finally defined, by assessing the spatial and temporal habitat variability for the target taxa or community, after combining these three components. During the process of physical habitat simulation some river processes, such as sediment transport and morphological changes, are often neglected while uncertainties arise from every component. We reviewed the elements that should be considered in every component of the physical habitat simulation to reduce uncertainties with emphasis on the actual trends on the topic and how sediment transport and river morphodynamics can be included within this methodological framework.
... From 2010 until today, novel research is undertaken to move beyond the original concept of e-flows. As initial studies linked the concept of e-flows with the magnitude and timing of flow releases from dams by estimating the minimum amount of water that is left in rivers and sustains their natural riparian and hydromorphological features (Acreman, Arthington, et al., 2014;Acreman, Overton, et al., 2014;Poff et al., 2016;Richter & Thomas, 2007), numerous methods have emerged that attempt to assess the environmental water requirements by allocating the flow components in a manner that maintains the ecosystem functionality (Poff & Matthews, 2013;Richter, 2010). Depending on whether the method uses strictly hydrologic data, or hydraulic and habitat information or a more complete set of river components, including societal uses, e-flow methods can be categorized as hydrological, hydraulic/ habitat, and holistic [Directorate-General for Environment (European Commission), 2015] ( includes studies that attempt to estimate the minimum flow that is vital to sustain the population of key aquatic biota (e.g., fish or benthic invertebrates) or to maintain the riparian vegetation, floodplains, and wetlands (Baumgartner et al., 2014;King et al., 2016;Lytle et al., 2017;Rivaes et al., 2017). ...
Chapter
In all available methodologies for the assessment of the environmental flow requirements, a sufficient knowledge of the natural hydrological regime is essential. In this chapter the hydrological data that are required in environmental flow assessment studies, their main characteristics, and their importance as well as the specific challenges in the case of mountainous areas are analyzed. The various available data sources, the measurement and processing of hydrological data, and the utilization of modeling techniques for the estimation of streamflow data in the case of ungauged or poorly gauged watersheds and for the naturalization of streamflow data are also presented. A short description of hydrological data series analysis for the determination of environmental water requirements is provided as well. Finally, sources for further reading are provided in each section.
... According to Lovejoy (2019), "Freshwater biodiversity has been particularly neglected because freshwater is widely understood and managed more as a physical resource vital to survival rather than as the special and delicate habitat that it provides for an extraordinary array of organisms." Consequently, while IWRM is seemingly based on parity, today there is a perceived lack of commitment to addressing the socio-ecological impacts of large dam development, canal and irrigation diversions, and other water development projects with negative repercussions on watershed integrity and local populations (Conca, 2006;Richter, 2010). This fact complicates the application of IWRM principles as emerging economies are faced with balancing social, economic, and environmental water needs in the face of climate change (Tickner and Acreman, 2013, p. 137). ...
Chapter
As conservation is an increasingly championed tool to promote nature-based adaptation strategies and ecosystem service and freshwater biodiversity protection, taking lessons from the creation of historical acts of environmental policy making may inform the creation and increased application of policies to foster resilient riverine. This chapter investigates the use of integrated water resource management (IWRM) principles and emergent ecosystem knowledge in the development of several water resource policies during the 1960s environmental era and their influence on the creation of the Wild and Scenic Rivers Act of 1968 (WSRA), the first free-flowing river conservation policy in the world. Analysis is grounded in discourse analysis of archival documents and theoretical approaches offered through the poststructural turn in political ecology. The concept of legibility for conservation purposes—including the surveying, cataloging, policymaking, and management of natural resources—is used to reframe the WSRA as a legibility act protecting riverine ecosystem services important to society and reveals the policy as a corollary of evolving national water governance priorities grounded in shifting perceptions of nature. Unlike work that characterizes the unintended consequences of legibility acts as state failures, this chapter offers the WSRA as a flexible conservation policy framework viable for broad application in the United States and adoption abroad as a climate adaptation policy.
... Flooding requirements for floodplain forest restoration need to be precisely quantified to assess if such flows are feasible because other dam functions and the dimensions of flow control structures limit the magnitude, duration, and timing of environmental flows (Richter 2010;Acreman et al. 2014;Owusu et al. 2020). Impacts of flow scenarios subject to these constraints can be analyzed with hydrologic models if aquatic and riparian species flow needs are known. ...
Article
Full-text available
Quantification of flooding thresholds that govern species distributions on microtopographic gradients in floodplains can help design environmental flows, but the multiple correlated dimensions of flooding such as frequency, depth, duration, and timing are a challenge. We postulated that species distributions are limited by the most stressful combination of flooding dimensions when the plants are in their most susceptible developmental stage. To test this idea, we measured survival of young seedlings in pots subjected to flood treatments that completely submerged the seedlings in stagnant water with and without suspended sediments for durations of up to 6 weeks during the growing season. This measure of flood tolerance predicted floodplain distributional limits of 16 tree species with high accuracy (adj. r2 = 0.91). The strength of the result suggests that seedling ability to survive complete submergence in stagnant water for prolonged periods is an important mechanism limiting species distributions in riparian forests. We propose that environmental flows that completely submerge the seedling layer in floodplain forest with stagnant water for at least 3 weeks are likely to be more effective at eliminating invading upland species than flows that only flood the soil up to the root collars of seedlings.
Article
Flow classification provides a statistically robust method of defining an expected range of variability for flow metrics describing frequency, magnitude, duration and timing of events. Here, we characterised reference mean daily flows for 1950–1999 for all 5 838 quinary catchments of South Africa based on 150 metrics. Using a two-tiered approach, where sub-catchments were classified into similar flow types using principal components and cluster analyses, we defined 6 to 12 flow types for each of 8 hydrological regions reflecting rainfall seasonality. Redundancy between variables was 87% on average, so that site variability could be accounted for using 8–28 metrics. In general, flow volume metrics accounted for Axis 1 variability, while coefficients of dispersion had 1.8 times less leverage in Axis 2. With the incorporation into a spatial product and an associated database, this study provides a basis for defining statistically robust reference flow conditions for multiple flow metrics, against which current observed flows at specific sites may be compared.
Book
Full-text available
This book is the Persian translation of ïts English version entitled "The Water Footprint Assessment Manual: Setting the Global Standard" authored by Hoekstra et al. (2011). To freely download the book, you can refer to the following link: https://waterfootprint.org/en/resources/publications/water-footprint-assessment-manual/
Article
Full-text available
A key question in sustainable development is how much alteration in natural systems, such as river basins, is acceptable? One of the ways by which humans alter a river basin is by building water storage infrastructure. While storage reservoirs deliver numerous benefits, they can also induce social and environmental costs by displacing people, fragmenting river networks and altering downstream flow regimes. In such a context, merely capping total water withdrawal from rivers for human consumption is not sufficient. River basin plans should also identify optimal (acceptable) limits to surface storage capacities, and optimal numbers, degrees of distribution and locations of storage infrastructure. It remains largely unclear, however, whether it is possible to define a hydrologically, ecologically and socially justified ‘surface water storage boundary’ for a river basin. An associated question is what would be the ‘best’ arrangement of this bounding storage capacity in the basin's river network (in terms of numbers, sizes and locations of reservoirs) to maximize water storage benefits and minimize environmental and social costs. The main objective of this review is to examine contemporary knowledge on surface water storage development with a focus on tools and approaches that may help to answer the above questions of a ‘surface water storage boundary’ and its ‘optimum arrangement’ for a river basin. In order to achieve this objective, our review introduces two novel concepts: the ‘storage scale’ and the ‘sustainable storage development framework.’ The ‘storage scale’ has four elements – capacity, number, distribution and location – individual scales that help visualize a ‘surface water storage boundary’ and its ‘optimum arrangement’ for a typical river basin. The ‘sustainable storage development framework’ consists of three dimensions – economic benefits, ecosystems and society- and a set of indicators quantifying each dimension. This review shows that optimal levels of the elements of the ‘storage scale’ may be identified using the ‘sustainable storage development framework’.
Article
Human actions and climate change have drastically altered river flows across the world, resulting in adverse effects on riverine ecosystems. Environmental flows (EFs) have emerged as a prominent tool for safeguarding the riverine ecosystems, but at the global scale, the assessment of EFs is associated with high uncertainty related to the hydrological data and EF methods employed. Here, we present a novel, in-depth global EF assessment using environmental flow envelopes (EFEs). Sub-basin-specific EFEs are determined for approximately 4400 sub-basins at a monthly time resolution, and their derivation considers the methodological uncertainties related to global-scale EF studies. In addition to a lower bound of discharge based on existing EF methods, we introduce an upper bound of discharge in the EFE. This upper bound enables areas to be identified where streamflow has substantially increased above natural levels. Further, instead of only showing whether EFs are violated over a time period, we quantify, for the first time, the frequency, severity, and trends of EFE violations during the recent historical period. Discharge was derived from global hydrological model outputs from the ISIMIP 2b ensemble. We use pre-industrial (1801–1860) quasi-natural discharge together with a suite of hydrological EF methods to estimate the EFEs. We then compare the EFEs with recent historical (1976–2005) discharge to assess the violations of the EFE. These violations most commonly manifest as insufficient streamflow during the low-flow season, with fewer violations during the intermediate-flow season, and only a few violations during the high-flow season. The EFE violations are widespread and occur in half of the sub-basins of the world during more than 5 % of the months between 1976 and 2005, which is double compared with the pre-industrial period. The trends in EFE violations have mainly been increasing, which will likely continue in the future with the projected hydroclimatic changes and increases in anthropogenic water use. Indications of increased upper extreme streamflow through EFE upper bound violations are relatively scarce and dispersed. Although local fine-tuning is necessary for practical applications, and further research on the coupling between quantitative discharge and riverine ecosystem responses at the global scale is required, the EFEs provide a quick and globally robust way of determining environmental flow allocations at the sub-basin scale to inform global research and policies on water resources management.
Preprint
Full-text available
The natural flow regime is considered the “master variable” in lotic systems, controlling structure and function at organismal, population, community, and ecosystem levels. We sought to estimate forested headwater stream metabolism across two dominant flow regimes ( Runoff and Groundwater ) in northern Arkansas and evaluate potential differences in, and drivers of, gross primary production, ecosystem respiration, and net ecosystem metabolism. Flow regimes differed in intermittency, substrate heterogeneity, hyporheic connectivity, and dominant water source (subsurface runoff vs. groundwater), which we expected to result in differences in primary production and respiration. Average daily gross primary production (GPP) and ecosystem respiration (ER) estimated from field data collected from May 2015-June 2016 tended to be greater in Groundwater streams. Respiration was positively related to discharge (R 2 = 0.98 p< 0.0001) and net metabolism became more heterotrophic with increasing average annual discharge across sites (R 2 = 0.94, p= 0.0008). Characterizing ecosystem-level responses to differences in flow can reveal mechanisms governing stream metabolism and, in turn, provide information regarding trophic state and energy inputs as efforts continue to determine global trends in aquatic carbon sources and fates.
Article
Full-text available
This paper addresses the questions of acceptable upper limits for storage development and how best to deploy storage capacity in the long-term planning of built surface water storage in river basins. Storage-yield curves are used to establish sustainable storage development pathways and limits for a basin under a range of environmental flow release scenarios. Optimal storage distribution at a sub-basin level, which complies with an identified storage development pathway, can also be estimated. Two new indices are introduced—Water Supply Sustainability and Environmental Flow Sustainability—to help decide which pathways and management strategies are the most appropriate for a basin. Average pathways and conservative and maximum storage limits are illustrated for two example basins. Conservative and maximum withdrawal limits from storage are in the range of 45–50% and 60–65% of the mean annual runoff. The approach can compare the current level of basin storage with an identified pathway and indicate which parts of a basin are over- or under-exploited. A global storage–yield–reliability relationship may also be developed using statistics of annual basin precipitation to facilitate water resource planning in ungauged basins.
Article
Full-text available
Study region Sarawak, Malaysia. Study focus This paper presents a framework (‘HyFFlow’) designed to provide a systematic characterisation of river flow regimes. HyFFlow consists of four packages, together yielding information on rainfall and flow patterns. They include analyses to identify and characterise different types of high flow event, based on their magnitude, shape and duration, and assessment of the timing and duration of periods of high and low flow. HyFFlow also includes assessment of temporal patterns (seasonality and long-term trends) in rainfall and flow. The characterisation provides a comprehensive baseline against which future changes can be assessed. New hydrologic insights for the region HyFFlow analyses indicated subtle and complex changes to long-term hydro-climatological conditions in the Baleh catchment, Malaysia: (i) analyses of the hydrograph indicated that there have been reductions in flow in the wet season, but not at other times of the year, and (ii) while there is no evidence of long-term trends in precipitation across the catchment (no change in monthly rainfall values over a 51- year period), there has been an increase in the number of days each month with no rainfall in some sub-catchments. HyFFlow analyses also identified four main types of high flow event in the Baleh whose functional roles need to be assessed as part of future geomorphic and ecological studies.
Article
In water resources management and practices, the time-connected duration and frequency of episodic low streamflow events (and droughts) are often needed for a range of purposes such as water supply planning, low flow management, and drought planning. However, the existing graphical tools commonly used in hydrology such as flow duration curves (FDC), discharge-duration-frequency (QdF), and severity-duration-frequency (SDF) curves, often do not provide this information. In this study, we contribute an approach to develop a flow-duration-frequency (FDF) curve by fitting the exponential function to graphically show the time-connected duration and frequency of episodic low streamflow events. The FDF fitting is comprehensively tested with a bootstrap resampling experiment using long-term continuous streamflow records for 92 USGS gages located in the state of Illinois, U.S.A. The experiment results reveal that the proposed methodology can reasonably develop FDF curves for episodic low streamflow events. The results demonstrate that the FDF fitting is improved by using longer streamflow record though the improvement appears to level off with 30 years or longer streamflow records. The results also confirm that the FDF fitting is more reliable for higher streamflow threshold to define episodic low streamflow events.
Article
Hydrologic processes are often key determinants of successful recruitment of native fishes. However, water management practices can result in abnormal changes in daily and seasonal hydrology patterns. Rarely has fish recruitment across river‐reservoir landscapes been considered in relation to flow management, despite the direct relationship between reservoir water management and the resulting upstream and downstream hydrology. We evaluated the relationships between lotic and lentic hydrology and recruitment of two native broadcast‐spawning fishes, Freshwater Drum Aplodinotus grunniens and Gizzard Shad Dorosoma cepedianum. Four seasonal periods for each species were identified that related to species’ spawning biology, from which we derived our remaining hydrology variables. Annual hydrology variables were also considered in our analysis. We developed regression models in conjunction with a model‐selection procedure for each species and habitat type based on catch‐curve residuals from fish populations in hydrologically connected river‐reservoir systems in the Ozark Highland and Ouachita Mountain ecoregions, USA. Our results indicated that recruitment of reservoir Freshwater Drum was negatively correlated to annual reservoir retention time. In lotic habitats, Freshwater Drum recruitment was positively correlated with prespawn discharge conditions and negatively correlated with annual flow variability. Similarly, riverine Gizzard Shad recruitment was positively correlated to the frequency of high flow pulses during the spawning period. Our results indicate releasing reservoir water to best mimic relatively natural flow patterns may benefit some broadcast spawning species occupying both lentic and downstream lotic environments, especially during the spring. This information, combined with future efforts on additional spawning guilds, will provide a foundation for developing holistic river‐reservoir water‐allocation plans.
Article
Full-text available
The local water regime of the small-scale Geisel catchment in Central Germany is vastly impacted by strong lignite-mining activities. Missing knowledge about hydrological regimes and low-flow discharges in this impacted region prevented integrated environmental flow assessments. As a consequence, targeted environmental flows of the lower Geisel usually cannot be achieved. To close this knowledge gap, we present a novel approach for an integrated environmental flow assessment in non-natural catchments using long-term baseflow rates, seen as an approach to environmental flows, and simple hydrological methods. Since baseflow rates cannot be estimated accurately in non-natural catchments, we combine 14 different hydrograph separation methods, statistical regionalization, and numerical catchment descriptors. The long-term baseflow equals 0.28 m³/s from 1981 to 2017 (75.4% of total discharge), and in the post-mining era since 2011, the mean baseflow equals 0.115m³/s (77.2% of total discharge). The combination of hydrograph separation with hydrological regionalization and numerical catchment descriptors reveals new opportunities for describing discharge components in non-natural catchments. Determined environmental flows are similar as achieved by other hydrological methods and can be linked to different intensities of anthropogenic impacts. The environmental flow assessment reveals required additional water amounts of 0.0608 m³/s during summer and 0.0874m³/s during winter for achieving quasi-natural flow regime conditions. The approaches enable long-term low-flow analyses and environmental flow assessments in mining impacted catchments.
Article
Full-text available
A global challenge for water resource management in rivers worldwide is ensuring water supply reliability satisfies consumptive and environmental demands. High variability in water supply, water policy and management decisions, and uncertainty about the effects of climate change compound this challenge. Understanding factors driving water allocations and consequences for water users and the environment is essential. Rainfall and streamflow traditionally drive allocations, yet the influence of water management decisions are often overlooked because they are complex, rarely codified and dependent on the regional context. We compared the relative influences of water management, climate and the river system characteristics including demand and water storage infrastructure on regulated and unregulated water allocations in two regulated rivers with large dams for water supply to towns, irrigated agriculture and wetlands of international significance (Gwydir and Macquarie Rivers of the Murray-Darling Basin, southeastern Australia), using hydrological simulation models and regression-based sensitivity analyses under an historical and drier climate. Water management decisions influenced regulated water allocations (explaining 23% to 52% of the variance) considerably more than unregulated water allocations (explaining 2%). For regulated water allocations, water management decisions and the river system were more important than a plausible change in climate, while for unregulated water allocations, the river system and climate change were dominant drivers. Changing management rules alone could vary long term water allocations by between -6% and +0.1% in the Gwydir River and between -4% and +22% in the Macquarie River. Management rules which allocated future inflows (i.e. credit model) were more likely to fail in a drying environment with projected reductions in runoff, compared to more rules where only water in storage is allocated (i.e. debit model). Management rules differed despite both river systems being governed by a single management agency under the same legislative and policy framework. More systematic approaches to justify water management rules and greater transparency in their influence on water allocations are critical for maximizing the benefits to water users and river health, and for managing risks to water supply in a variable and changing climate.
Chapter
Full-text available
The Zambezi Delta is a wetland system of profound conservation and resource value. The delta is home to more than 350 000 rural villagers, who depend on the delta's rich natural resources for their livelihood. The delta is also the largest wetland system in the Zambezi catchment, and supports a great mosaic of wetland vegetation communities, including palm savanna, mangrove forests and papyrus swamps. Vast, seasonally flooded grasslands support diverse and abundant wildlife populations, including many waterbird species of international concern, and, until recently, legendary concentrations of buffalo, waterbuck and hippopotamus. The floodplain provides spawning grounds for riverine and anadromous fishes and critical dry-season grazing lands for domesticated livestock and wildlife. Extensive coastal mangroves and estuaries support a lucrative prawn fishery. Of particular importance is the 5 000 km 2 Marromeu Complex, located along the southern bank of the Lower Zambezi River in the delta, which includes the protected Marromeu Buffalo Reserve and three managed hunting units (Figure 2.1). Throughout recorded history, the Zambezi Delta has undergone constant change in response to resource utilization pressures, climatic cycles, natural geomorphic processes, and especially the complex interactions between the indigenous delta population and successive traders and colonial inhabitants. During the past forty years, however, civil war, drought and the construction of large dams on the Zambezi River have resulted in unprecedented land use and land cover changes that threaten the ecological and social fabric of the delta. The International Crane Foundation and Dutton Environmental Consultants were approached by the Biodiversity Foundation for Africa to assess the history of land use and land cover change in the Zambezi Delta, Mozambique, for the World Conservation Union (IUCN) Zambezi Basin Wetlands Conservation and Resource Utilisation Project. The terms of reference for this study are (a) to provide an historical account of land use and cover change in the Zambezi Delta, (b) to identify factors influencing land use and land cover change in the Zambezi Delta, (c) to discuss the implications of land use and ecological change in the Zambezi Delta on biodiversity and human welfare, and (d) to provide recommendations for the amelioration of negative land use and ecological changes in the Zambezi Delta. We begin with a brief history of land use in the Zambezi Delta, followed by a comprehensive review of previous studies of land cover and land use change. These studies provide a basis for quantitative assessment of changes in the delta. Its present status and the patterns, causes and implications of land use and land cover change are then assessed using a combination of aerial photographs, satellite images, aerial surveys, field research, and interviews. The study provides recommendations for balancing the wise use of the natural resources of the delta with the conservation of its biological diversity.
Article
Full-text available
Potential changes in the availability of water resources are one of the greatest concerns relating to global climate warming. Socio-economic developments will also influence water use and demands. This study was conducted to evaluate potential changes in water withdrawals and availability under various socio-economic and climate change scenarios. In the current paper, which presents the first part of the study, future potential water withdrawals are projected according to socio-economic driving factors under the scenarios A1b, A2, B1, and B2 of the Special Report on Emission Scenarios (SRES), which was released for the Fourth Assessment Report on global warming by the Intergovernmental Panel on Climate Change (IPCC-AR4) in 2000. Total world water withdrawal is currently approximately 3800 km3/year, and will likely exceed 6000 km3/year by 2055, according to all scenarios. Water withdrawal is projected to increase in the future, but change trends largely depend on the socio-economic scenarios. Scenario A2 shows the extreme situation of continuously increasing water withdrawal. The scenario with global cooperation on solutions to social, economic, and environmental issues (Scenario B1) illustrates that society can reach relatively higher economic development by using less water and thus encourages sustainable governance of world water resources. In addition, comparison with other studies is conducted to help us understand the uncertainty range when projecting world water withdrawals according to different methods and assumptions.
Article
Full-text available
Rivanna Water and Sewer Authority (RWSA), which operates three reservoirs in the Rivanna River Basin to supply water to the outlying areas in Albemarle County has implemented stringent and mandatory water conservation measures to be able to survive the drought. Throughout the planning process, local environmental interests argued strongly for better protection of the rivers being tapped by RWSA. Only minimum flows are released from the reservoirs when reservoir levels drop below the spillways, and the reservoir releases equal less than 20% of the nondepleted less than 20% of the nondepleted normal conditions. A reservoir operating plan was devised that sets environmental flow releases according to a varying percentage of the inflows to the reservoir. RWSA plans to use a simple forecasting approach to help them implement the various stages of the drought management plan.
Article
Full-text available
umans have long been fasci- nated by the dynamism of free-flowing waters. Yet we have expended great effort to tame i rivers for transportation, water sup- ply, flood control, agriculture, and ; f
Article
Full-text available
1. The flow regime is a primary determinant of the structure and function of aquatic and riparian ecosystems for streams and rivers. Hydrologic alteration has impaired riverine ecosystems on a global scale, and the pace and intensity of human development greatly exceeds the ability of scientists to assess the effects on a river-by-river basis. Current scientific understanding of hydrologic controls on riverine ecosystems and experience gained from individual river studies support development of environmental flow standards at the regional scale.
Article
Full-text available
The Southwest Florida Water Management District has implemented a management approach for unimpounded rivers that limits withdrawals to a percentage of streamflow at the time of withdrawal. The natural flow regime of the contributing river is considered to be the baseline for assessing the effects of withdrawals. Development of the percent-of-flow approach has emphasized the interaction of freshwater inflow with the overlap of stationary and dynamic habitat components in tidal river zones of larger estuarine systems. Since the responses of key estuarine characteristics (e.g., isohaline locations, residence times) to freshwater inflow are frequently nonlinear, the approach is designed to prevent impacts to estuarine resources during sensitive low-inflow periods and to allow water supplies to become gradually more uvailable as inflow increases. A high sensitivity to variation at low inflow extends to many invertebrates and fishes that move upstream and downstream in synchrony with inflow. Total numbers of estuarine-resident and estuarine-dependent organisms have been found to decrease during low-inflow periods, including mysids, grass shrimp, and juveniles of the bay anchovy and sand seatrout. The interaction of freshwater inflow with seasonal processes, such as phytoplankton production and the recruitment of fishes to the tidal-river nursery, indicates that withdrawal percentages during the springtime should be most restrictive. Ongoing efforts are oriented toward refining percentage withdrawal limits among seasons and flow ranges to account for shifts in the responsiveness of estuarine processes to reductions in freshwater inflow.
Article
Full-text available
The flow regime is regarded by many aquatic ecologists to be the key driver of river and floodplain wetland ecosystems. We have focused this literature review around four key principles to highlight the important mechanisms that link hydrology and aquatic biodiversity and to illustrate the consequent impacts of altered flow regimes: Firstly, flow is a major determinant of physical habitat in streams, which in turn is a major determinant of biotic composition; Secondly, aquatic species have evolved life history strategies primarily in direct response to the natural flow regimes; Thirdly, maintenance of natural patterns of longitudinal and lateral connectivity is essential to the viability of populations of many riverine species; Finally, the invasion and success of exotic and introduced species in rivers is facilitated by the alteration of flow regimes. The impacts of flow change are manifest across broad taxonomic groups including riverine plants, invertebrates, and fish. Despite growing recognition of these relationships, ecologists still struggle to predict and quantify biotic responses to altered flow regimes. One obvious difficulty is the ability to distinguish the direct effects of modified flow regimes from impacts associated with land-use change that often accompanies water resource development. Currently, evidence about how rivers function in relation to flow regime and the flows that aquatic organisms need exists largely as a series of untested hypotheses. To overcome these problems, aquatic science needs to move quickly into a manipulative or experimental phase, preferably with the aims of restoration and measuring ecosystem response.
Article
Full-text available
The lower Roanoke River in North Carolina, USA, has been regulated by a series of dams since the 1950s. This river and its floodplain have been identified by The Nature Conservancy, the US Fish and Wildlife Service, and the State of North Carolina as critical resources for the conservation of bottomland hardwoods and other riparian and in-stream biota and communities. Upstream dams are causing extended floods in the growing season for bottomland hardwood forests, threatening their survival. A coalition of stakeholders including public agencies and private organizations is cooperating with the dam managers to establish an active adaptive management program to reduce the negative impacts of flow regulation, especially extended growing season inundation, on these conservation targets. We introduce the lower Roanoke River, describe the regulatory context for negotiating towards an active adaptive management program, present our conservation objective for bottomland hardwoods, and describe investigations in which we successfully employed a series of models to develop testable management hypotheses. We propose adaptive management strategies that we believe will enable the bottomland hardwoods to regenerate and support their associated biota and that are reasonable, flexible, and economically sustainable.
Article
Many African river floodplains are disappearing or being modified as the result of water management activities, in particular large-scale irrigation schemes. Often any resulting impact on downstream wetland benefits is ignored. By combining hydrological and economic analyses we simulate different scenarios for large-scale irrigation schemes in the Hadejia-Jama'are River Basin in northern Nigeria. We compare the agricultural, fishing and fuelwood benefits lost through reduced flooding downstream against the gains from increased irrigation production upstream. Our analysis suggests that the irrigation benefits can only partially replace the lost benefits from reduced floodplain inundation. Given that several upstream irrigation schemes are completed or currently under construction, our simulations show that the introduction of regulated flood releases is the best hope of minimizing further losses of floodplain benefits. Further expansion of large-scale irrigation within the river basin should also be avoided.
Article
Water withdrawals in the United States during 1985 were estimated to average 399 000 million gallons per day (Mgal/d) of freshwater and saline water for offstream uses - 10% less than the 1980 estimate. Average per capita use for all offstream uses was 1650 gallons per day (gal/d) of freshwater and saline water combined and 1400 gal/d of freshwater alone. The 1985 estimates of total water withdrawals and consumptive use were less than the 1980 estimates; this apparently further confirms a general trend indicated by a slackening in the rate of increase of total withdrawals from 1970 to 1975 and again from 1975 to 1980. Public-supply withdrawals during 1985 were 7% more than during 1980, self-supplied domestic withdrawals were 4% less, irrigation withdrawals were 6% less, livestock withdrawals were 108% more, and thermoelectrie power withdrawals were 13% less. The combined total for self-supplied industrial, commercial, and mining withdrawals (excluding thermoelectric power) was 30 500 Mgal/d during 1985, or 33% less than withdrawals listed for "other' industries during 1980, which also included commercial and mining uses. -from Authors
Article
Flow patterns in the Great Fish River in the Eastern Cape province of South Africa have changed from being seasonal, with predictable no-flow periods during winter, to perennial following the completion of an inter-basin transfer scheme in 1977 to provide a regular supply of irrigation water. Simulium chutteri (Diptera: Simuliidae) consequently became a problem species of pestilential proportions, due to increased flow volumes and current velocities favouring this species. In this study, aquatic invertebrates were sampled from the stones-in-current biotope with a range of current velocities at three sites on the Great Fish River, with a particular focus on pool/rapid areas favouring S. chutteri. The main aim of this paper was to determine whether critical hydraulic thresholds, including current velocity, could be derived for this species. Knowledge of the hydraulic preferences of S. chutteri is a prerequisite for any integrated control programme which combines larvicidal control with flow manipulation. S. chutteri was found to favour the rapids biotope with current velocities in excess of 90 cms−1, with preferences for higher current velocities increasing with life cycle stage. Additional hydraulic variables, at the scale measured in this study, did not correlate with larval densities. There is potential for more effective long-term control of problem populations of larval blackfly in the Great Fish River through further research on the potential for using constructed in-stream vanes to reduce current velocities in rapids of the river at critical periods of the year (July–October), based on flow duration/current velocity relationships. Copyright © 2007 John Wiley & Sons, Ltd.
Article
Recognition of the escalating hydrological alteration of rivers on a global scale and resultant environmental degradation, has led to the establishment of the science of environmental flow assessment whereby the quantity and quality of water required for ecosystem conservation and resource protection are determined. A global review of the present status of environmental flow methodologies revealed the existence of some 207 individual methodologies, recorded for 44 countries within six world regions. These could be differentiated into hydrological, hydraulic rating, habitat simulation and holistic methodologies, with a further two categories representing combination-type and other approaches. Although historically, the United States has been at the forefront of the development and application of methodologies for prescribing environmental flows, using 37% of the global pool of techniques, parallel initiatives in other parts of the world have increasingly provided the impetus for significant advances in the field. Application of methodologies is typically at two or more levels. (1) Reconnaissance-level initiatives relying on hydrological methodologies are the largest group (30% of the global total), applied in all world regions. Commonly, a modified Tennant method or arbitrary low flow indices is adopted, but efforts to enhance the ecological relevance and transferability of techniques across different regions and river types are underway. (2) At more comprehensive scales of assessment, two avenues of applica-tion of methodologies exist. In developed countries of the northern hemisphere, particularly, the instream flow incremental methodology (IFIM) or other similarly structured approaches are used. As a group, these methodologies are the second most widely applied worldwide, with emphasis on complex, hydrodynamic habitat modelling. The establishment of holistic meth-odologies as 8% of the global total within a decade, marks an alternative route by which environmental flow assessment has advanced. Such methodologies, several of which are scenario-based, address the flow requirements of the entire riverine eco-system, based on explicit links between changes in flow regime and the consequences for the biophysical environment. Recent advancements include the consideration of ecosystem-dependent livelihoods and a benchmarking process suitable for evaluat-ing alternative water resource developments at basin scale, in relatively poorly known systems. Although centred in Australia and South Africa, holistic methodologies have stimulated considerable interest elsewhere. They may be especially appropriate in developing world regions, where environmental flow research is in its infancy and water allocations for ecosystems must, for the time being at least, be based on scant data, best professional judgement and risk assessment.
Article
Human demands on the world's available freshwater supplies continue to grow as the global population increases. In the endeavor to manage water to meet human needs, the needs of freshwater species and ecosystems have largely been neglected, and the ecological consequences have been tragic. Healthy freshwater ecosystems provide a wealth of goods and services for society, but our appropriation of freshwater flows must be better managed if we hope to sustain these benefits and freshwater biodiversity. We offer a framework for developing an ecologically sustainable water management program, in which human needs for water are met by storing and diverting water in a manner that can sustain or restore the ecological integrity of affected river ecosystems. Our six-step process includes: (1) developing initial numerical estimates of key aspects of river flow necessary to sustain native species and natural ecosystem functions; (2) accounting for human uses of water, both current and future, through development of a computerized hydrologic simulation model that facilitates examination of human-induced alterations to river flow regimes; (3) assessing incompatibilities between human and ecosystem needs with particular attention to their spatial and temporal character; (4) collaboratively searching for solutions to resolve incompatibilities; (5) conducting water management experiments to resolve critical uncertainties that frustrate efforts to integrate human and ecosystem needs; and (6) designing and implementing an adaptive management program to facilitate ecologically sustainable water management for the long term. Drawing from case studies around the world to illustrate our framework, we suggest that ecologically sustainable water management is attainable in the vast majority of the world's river basins. However, this quest will become far less feasible if we wait until water supplies are further over-appropriated.
Article
Conflicts between intensive groundwater use and wetland conservation are widespread throughout arid and semiarid regions worldwide. These have become more significant wherever there has been a synchronism between pumping-based human development and the awakening of an environmental awareness in society. The Mancha Occidental aquifer provides an example of such an occurrence, which has given rise to noteworthy social conflicts. This paper presents a cross-policy analysis for wetland restoration measures, establishing the main reasons why funding-intensive agricultural, environmental, and water policies have only attained marginal success in recovering the area’s aquatic ecosystems.
DOI: 10.1002/rra RE-THINKING ENVIRONMENTAL FLOWS rBunn SE, Arthington AH. 2002. Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity
  • John Copyright
  • Wiley
  • Sons
Copyright # 2009 John Wiley & Sons, Ltd. River. Res. Applic. (2009) DOI: 10.1002/rra RE-THINKING ENVIRONMENTAL FLOWS rBunn SE, Arthington AH. 2002. Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity. Environmental Management 30: 492–507
Land cover and land use changes in the Zambezi Delta In Biodiversity of the Zambezi Basin Wetlands. Volume III. Land Use Change and Human Impacts Consultancy report for IUCN ROSA. Biodiversity Foundation for Africa/The Zambezi Society: Bulawayo/Harare
  • Rd Beilfuss
  • Moore P D Dutton
Beilfuss RD, Dutton P, Moore D. 2000. Land cover and land use changes in the Zambezi Delta. In Biodiversity of the Zambezi Basin Wetlands. Volume III. Land Use Change and Human Impacts, Timberlake J (ed.). Consultancy report for IUCN ROSA. Biodiversity Foundation for Africa/The Zambezi Society: Bulawayo/Harare. 31–106
DOI: 10.1002/rra Bunn SE, Arthington AH. 2002. Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity
  • Copyright
Copyright # 2009 John Wiley & Sons, Ltd. River Res. Applic. 26: 1052–1063 (2010) DOI: 10.1002/rra Bunn SE, Arthington AH. 2002. Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity. Environmental Management 30: 492–507.
Rivers for Life: Managing Water for People and Nature Ecologically sustainable water management: managing river flows for ecological integrity
  • S Postel
  • Richter
  • Dc Washington
  • Mathews Bd R Richter
  • Harrison Dl Wigington
Postel S, Richter B. 2003. Rivers for Life: Managing Water for People and Nature. Island Press: Washington DC. Richter BD, Mathews R, Harrison DL, Wigington R. 2003. Ecologically sustainable water management: managing river flows for ecological integrity. Ecological Applications 13: 206–224.
Development of a Protocol for the Definition of the Desired State of Riverine Systems in South Africa. Department of Environmental Affairs and Tourism: South Africa Projection of future world water resources under SRES scenarios: water withdrawal
  • Rogers Kh Bestbier
  • Y Shen
  • T Oki
  • N Utsumi
  • S Kanae
  • Hanasaki
Rogers KH, Bestbier R. 1997. Development of a Protocol for the Definition of the Desired State of Riverine Systems in South Africa. Department of Environmental Affairs and Tourism: South Africa. Shen Y, Oki T, Utsumi N, Kanae S, Hanasaki N. 2008. Projection of future world water resources under SRES scenarios: water withdrawal. Hydrological Sciences 53: 11–33.
Delivering multi-objective environmental flows into terminal floodplain wetlands, Northern Murray-Darling Basin, Australia
  • Wilson Gg Berney
  • Pj
Wilson GG, Berney PJ. 2009. Delivering multi-objective environmental flows into terminal floodplain wetlands, Northern Murray-Darling Basin, Australia. Proceedings of the International Conference on Environmental Water Allocations, Port Elizabeth, South Africa. Copyright # 2009 John Wiley & Sons, Ltd. River Res. Applic. 26: 1052–1063 (2010) DOI: 10.1002/rra RE-THINKING ENVIRONMENTAL FLOWS
Eco-Hydrological Databases: Estimates of Environmental Flows Worldwide Database accessed on March24 Integrated Water Resources Management in Practice: Better Water Management for Development
  • M Muller
IWMI (International Water Management Institute). 2009. Eco-Hydrological Databases: Estimates of Environmental Flows Worldwide. Database accessed on March24, 2009 at URL: http://dw.iwmi.org/ehdb/efr/wetlandvisitor/information.aspx Lenton R, Muller M. 2009. Integrated Water Resources Management in Practice: Better Water Management for Development. Earthscan Publications: London.
Flow—The Essentials of Environmental Flows
  • M Dyson
  • G Bergkamp
  • J Scanlon
Dyson M, Bergkamp G, Scanlon J (eds). 2008. Flow—The Essentials of Environmental Flows. IUCN: Gland, Switzerland.
Governor Perdue Declares Emergency; Requests Presidential Intervention
  • Sonny Governor
  • Perdue
Governor Sonny Perdue. 2007. Governor Perdue Declares Emergency; Requests Presidential Intervention. Press release from the Office of the Governor of Georgia, October 20.
  • Solley
Delivering multi-objective environmental flows into terminal floodplain wetlands
  • G G Wilson
  • P J Berney