IMPLEMENTING ENVIRONMENTAL FLOWS IN COMPLEX WATER RESOURCES SYSTEMS – CASE STUDY: THE DUERO RIVER BASIN,SPAIN

European river basin authorities are responsible for the implementation of the new river basin management plans in accordance with the European Water Framework Directive. This paper presents a new methodology framework and approach to define and evaluate environmental flow regimes in the realistic complexities that exist with multiple water resource needs at a basin scale. This approach links river basin simulation models and habitat time series analysis to generate ranges of environmental flows (e‐flows), which are evaluated by using habitat, hydropower production and reliability of water supply criteria to produce best possible alternatives. With the use of these tools, the effects of the proposed e‐flows have been assessed to help in the consultation process. The possible effects analysed are impacts on water supply reliability, hydropower production and aquatic habitat. After public agreements, a heuristic optimization process was applied to maximize e‐flows and habitat indicators, while maintaining a legal level of reliability for water resource demands. The final optimal e‐flows were considered for the river basin management plans of the Duero river basin. This paper demonstrates the importance of considering quantitative hydrologic and ecological aspects of e‐flows at the basin scale in addressing complex water resource systems. This approach merges standard methods such as physical habitat simulations and time series analyses for evaluating alternatives, with recent methods to simulate and optimize water management alternatives in river networks. It can be integrated with or used to complement other frameworks for e‐flow assessments such as the In‐stream Flow Incremental Methodology and Ecological Limits of Hydrologic Alteration. Copyright © 2011 John Wiley & Sons, Ltd.     

A collaborative and adaptive process for developing environmental flow recommendations

Many river restoration projects are focusing on restoring environmental flow regimes to improve ecosystem health in rivers that have been developed for water supply, hydropower generation, flood control, navigation, and other purposes. In efforts to prevent future ecological damage, water supply planners in some parts of the world are beginning to address the water needs of river ecosystems proactively by reserving some portion of river flows for ecosystem support. These restorative and protective actions require development of scientifically credible estimates of environmental flow needs. This paper describes an adaptive, inter‐disciplinary, science‐based process for developing environmental flow recommendations. It has been designed for use in a variety of water management activities, including flow restoration projects, and can be tailored according to available time and resources for determining environmental flow needs. The five‐step process includes: (1) an orientation meeting; (2) a literature review and summary of existing knowledge about flow‐dependent biota and ecological processes of concern; (3) a workshop to develop ecological objectives and initial flow recommendations, and identify key information gaps; (4) implementation of the flow recommendations on a trial basis to test hypotheses and reduce uncertainties; and (5) monitoring system response and conducting further research as warranted. A range of recommended flows are developed for the low flows in each month, high flow pulses throughout the year, and floods with targeted inter‐annual frequencies. We describe an application of this process to the Savannah River, in which the resultant flow recommendations were incorporated into a comprehensive river basin planning process conducted by the Corps of Engineers, and used to initiate the adaptive management of Thurmond Dam. Copyright © 2006 John Wiley & Sons, Ltd.     

Socioeconomic Value(s) of Restoring Environmental Flows: Systematic Review and Guidance for Assessment

The preservation of instream flows entails multiple benefits not only for river ecosystems but also for human well‐being. Benefits of marketed goods and services provided by water withdrawals such as irrigation, water supply and hydropower production are well‐known. Others, such as recreational, aesthetic, cultural and existence values of a well‐preserved river flows are less studied. There is an increasing interest of policy makers to understand the benefits of costly river ecosystem restoration measures. Moreover, disregarding such benefits may turn into inter‐stakeholder conflicts. This paper reviews empirically‐based literature assessing environmental flows restoration/conservation. Thus, it offers the state‐of‐the‐art on three aspects: 1) what motivations drive the socioeconomic evaluation of instream flows (policies and alternative instream flow regimes); 2) what values and benefits are associated with instream flows (e.g. the sheer existence of a well‐preserved river, productive assets and cultural attributes); and 3) what methods are employed to undertake such assessments (e.g. scenario development, monetary and non‐monetary valuations, and stakeholders engagement). Building on this, we propose a methodological framework for case‐specific assessments of the restoration of environmental flows. This proposal combines increased stakeholder participation, better understanding of ecosystem functioning, awareness of the plurality of values and an accurate choice of valuation methods. Copyright © 2016 John Wiley & Sons, Ltd.     

Instream flow methods: a comparison of approaches

Minimum flows in rivers and streams aim to provide a certain level of protection for the aquatic environment. The level of protection is described by a measure such as a prescribed proportion of historic flows, wetted perimeter or suitable habitat. Conflicting minimum flow assessments from different instream flow methods are arguably the result of different environmental goals and levels of protection. The goals, the way in which levels of protection are specified, and the relationship between levels of protection and the aquatic environment are examined for three major categories of flow assessment methods: historic flow, hydraulic geometry and habitat. Basic conceptual differences are identified. Flow assessments by historic flow and hydraulic methods are related to river size and tend to retain the ‘character’ of a river. Habitat-based methods make no a priori assumptions about the natural state of the river and flow assessments are based primarily on water depth and velocity requirements. Flow and hydraulic methods assume that lower than natural flows will degrade the stream ecosystem, whereas habitat methods accept the possibility that aspects of the natural ecosystem can be enhanced by other than naturally occurring flows. Application of hydraulic and habitat methods suggests that the environmental response to flow is not linear; the relative change in width and habitat with flow is greater for small rivers than for large. Small rivers are more ‘at risk’ than large rivers and require a higher proportion of the average flow to maintain similar levels of environmental protection. Habitat methods are focused on target species or specific instream uses, and are useful where there are clear management objectives and an understanding of ecosystem requirements. Flow and hydraulic methods are useful in cases where there is a poor understanding of the ecosystem or where a high level of protection for an existing ecosystem is required. © 1997 John Wiley & Sons, Ltd.     

Ecohydrological Landscape Management for Human Well-Being

Abstract

This paper introduces a new perspective on water resources emphasizing the role of water vapor flows for human well-being. The connections between freshwater and ecosystem services in terrestrial environments are addressed, particularly the role of freshwater for the biota that sustains the flow of ecosystem services and the role of the biota that modifies freshwater flows. First, the water dependence of terrestrial ecosystem services and food production are analyzed. Secondly, two examples of unintentional, large-scale, water-mediated cascading effects related to ecosystem services that result from local, uncoordinated decisions in Australia and South Africa are discussed. These two countries are taking the lead in the management of freshwater flows and terrestrial ecosystem services. Issues including potential conflicts of interest and trade-offs between food (or timber) production and ecosystem services at the catchment scale are taken into account. A world-wide, intentional ecohydrological landscape approach to handle these issues is suggested. One important step towards a more integrated approach to freshwater is the development of flexible institutional structures.     

Water governance,ecosystems and sustainability: a review of progress in South Africa

It is approaching two decades since South Africa's democratic transformation introduced a visionary approach to water resources management. The earlier challenges of water law reform have given way to the greater undertaking of implementation. This paper reviews progress in relation to 7 of the 10 key challenges of the Africa Water Vision 2025. Progress in many areas has been slow, including establishment of catchment management institutions and implementation of environmental flows. Concerns remain regarding poor water quality and aquatic ecosystem health. A significant threat is the persistent shortage of skilled water professionals.     

生态环境用水的实践

生态环境用水是关于水资源管理的一个综合性思维方法，可以为人类社会可持续发展发挥重要作用。近几十年来，这一科学概念得到越来越多国家的关注。但是，在生态环境用水的实践方面，发达国家和发展中国家存在巨大的差距。从政策与立法、管理策略和组织机构能力3方面对生态环境用水在世界其他国家和中国的实践进行了分析比较。通过研究得出国家政策与法律、国际协定、公众参与、市场机制、公众意识、技术支持和流域管理是影响生态环境用水实践的关键因素，并以此为依据明确了中国生态环境用水实践的现状，最后为如何推动中国生态环境用水的实践提出了建议。     

Stakeholder‐enhanced environmental flow assessment: The Rufiji Basin case study in Tanzania

Environmental flows are now a standard part of sustainable water management globally but are only rarely implemented. One reason may be insufficient engagement of stakeholders and their priority outcomes in the environmental flow‐setting process. A recent environmental flow assessment (EFA) in the Kilombero basin of the Rufiji River in Tanzania concentrated on a broad‐based investigation of stakeholders' use and perceptions of the ecosystem services provided by the river as a framework for the assessment of flow regimes that would maintain them. The EFA process generally followed the Building Block Methodology but within an enhanced stakeholder engagement framework. Engagement began with the involvement of institutional stakeholders to explain the purpose of the EFA and to elicit their priority outcomes. Extensive interactions with direct‐use stakeholders followed to investigate their uses of and priorities for the rivers. Results were used by the EFA specialist team in choosing flow indicators and defining measurable environmental objectives. The specialists then met to reach a consensus of the flow requirements. The EFA results were lastly reported back to stakeholders. During the Kilombero EFA, we learned that stakeholders at all levels have a good awareness of the natural services provided by a healthy river and can contribute to the setting of environmental objectives for the rivers and floodplain. These can be factored into the biophysical assessments of river flows required to maintain habitats, processes, water quality, and biodiversity. It is therefore important to allocate significant resources to stakeholder engagement. It now remains to be seen if enhanced stakeholder engagement, including the increased understanding and capacity built among all stakeholders, will increase support for the implementation of the recommended flows.     

Bridging gaps between environmental flows theory and practices in China

In recent decades,a series of policies and practices for environmental flows(e-flows) have been implemented in China,with the sustainable development goal of balancing the utilization and protection of water resources among social,economic,and ecological needs.The aims of this study were to determine the main challenges and issues in e-flows implementation at different scales by analyzing policies and practices for eflows in China,and to propose some recommendations for bridging the gaps between the science and implementation of e-flows.The gaps between the science and implementation of e-flows were found after review of literature,policies,and practices,and it was found that ecological flow was a more widely used term by the government,rather than e-flows,in implementation.The plans and effects of e-flows implementation are discussed in this paper and challenges of e-flows implementation are recognized:(1) limited water resources and uneven spatial and temporal distribution,(2) a weak scientific basis for e-flows implementation,(3) poor operability of e-flows science,and(4) ineffective supervision and guarantee measures.The recommendations are(1) to strengthen the scientific foundation of e-flows,(2) to improve effectiveness in application of e-flows science,and(3) to propose operable and effective supervision and guarantee measures.This paper elaborates the current understanding of e-flows science and provides practical recommendations for implementing e-flows and for improving the effectiveness in e-flows implementation.To bridge the gaps between science and implementation of e-flows and improve the operability of policies in future practices,more scientific research on practices is recommended through adaptive management.     

EVALUATING TRADEOFFS BETWEEN ENVIRONMENTAL FLOW PROTECTIONS AND AGRICULTURAL WATER SECURITY

River basin managers responsible for water allocation decisions are increasingly required to evaluate tradeoffs between environmental flow protections and human water security. However, the basin‐scale effects of environmental flow regulations on water users are not well understood, in part because analyses are complicated by the spatial and temporal variation in water availability, human demands, and ecosystem needs. Here, we examine alternative regional environmental flow policies and their effects on a distributed network of water users in a small (182 km²) river basin in coastal California. We use a hydrologic model to simulate water diversion operations under three policy scenarios and quantify potential impacts to bypass flows for adult migrating salmon and agricultural water storage. The results indicate that there are inherent tradeoffs between environmental flows and agricultural water security, with the most restrictive environmental policy associated with the greatest impacts to water users. Surprisingly, the moderate environmental flow policy had larger impacts to bypass flows than the unregulated management scenario, suggesting that ecological benefits of the moderate policy are small relative to the adverse effects on agricultural water users. Conflicts between environmental and human water needs were greatest in upper catchments (<2.5 km²), where flow protections caused the greatest reduction in water storage. Although natural supplies were adequate for meeting water needs in most years regardless of policy restrictions, potential for conflict between environmental flow protections and water security was evident in dry years. Therefore, strategies are particularly needed for drought‐year water management to ensure adequate environmental flows while reducing human water allocations in an equitable manner. Copyright © 2013 John Wiley & Sons, Ltd.     

Environmental Flows Under the WFD Implementation

The Water Framework Directive (WFD) is the first piece of European environmental legislation addressing hydromorphological modifications and impacts on water bodies. Accordingly, in those water bodies where the hydromorphological pressures are having an impact on the ecological status, action is needed to achieve WFD objectives. Environmental flows appeared as one of the answers to this challenge. Due to their importance, Member States (MSs) have been looking to integrate ecological flows in the River Basin Management Plans (RBMPs) and Programmes of Measures (PoMs). More than seventeen years after the WFD adoption, this study aims to provide a systematic review of the use of environmental flows within the process of WFD implementation and their contribution to the achievement of environmental objectives. In order to achieve the goals of the study, a special analysis was done using: i) the WFD official documentation reporting the progress of WFD and environmental flows definition and implementation (such as the CIS Guidance n° 31), as well as, ii) the answers to key questions addressed to EU MSs representatives involved in the implementation of environmental flows. These enabled us to perceive how this topic has been addressed in MSs. Based on the gathered information the authors assessed whether a change in the environmental flows’ situation, between the 1st and 2nd RBMPs, has occurred by each MS, or whether progress on environmental flows assessments has been made. Furthermore, this study also highlights some MSs representatives comments related with the role of the Guidance n°31 and some relevant information related with the 3rd RBMPs. Even though an evolution on environmental flows assessments can be perceived, with an increase in MSs defining and incorporating environmental flows within the 2nd RBMPs and in the complexity of the conducted approaches, there is still a long way to go. Namely, it could be highlighted that more efforts are required for the: i) implementation of environmental flows and the monitoring of its effects in the water bodies status, ii) development of a verifiable link between environmental flows and biological indicators.     

Increase of River Base Flow by Hydropower Gate Operation for Mitigation of CSO Impacts – Potential and Limitations

In this paper the measure of increased river base flow is developed and evaluated. Aim is the temporal increase of flow in manmade low flow stretches for sufficient dilution of downstream acute pollution introduced by combined sewer overflows (CSOs). The increase of flow is done by operating upstream located retaining structures such as hydropower intakes. For implementation both energy producers and municipalities are required to cooperate. Thus the measure fits into a core aim of the Water Framework Directive of having basin wide approaches for improvements. Technically the focus of the measure is clearly on the mitigation of acute pollution, not addressing delayed or accumulate pollutants. The framework and implications are discussed for having an appropriate real time control (RTC) concept based on model based predictive control (MBPC). A specially development algorithm for the operation is presented and subsequently tested off-line with a semi-virtual catchment. The boundary conditions of the catchment are varied with regard to the connected catchment size, the river connected and the pollutant concentration originating from the catchment. Based on these scenarios and a review on uncertainties in rain forecasts, limits for the measure are derived. Costs for the measure were estimated as equivalent cost due to losses in energy production. It is shown that not only the costs for annual spilled water are to be considered but as well peak flows generated in the river system. The increase of CSO volume as an alternative measure was not found to be a suitable measure, leading to unrealistic high volumes and consequently to exorbitant costs.     

对开展城市总体规划水资源论证的思考

城市总体规划水资源论证是规划水资源论证的重要工作对象和内容,对保障城市总体规划的有效实施具有重要意义.从当前开展城市总体规划水资源论证工作遇到的主要问题入手,对城市总体规划水资源论证的介入时机、工作定位、主要内容以及技术路线等关键环节进行了分析,提出了推进城市总体规划水资源论证工作的对策与措施.     

ASSESSING THE CUMULATIVE IMPACTS OF HYDROPOWER REGULATION ON THE FLOW CHARACTERISTICS OF A LARGE ATLANTIC SALMON RIVER SYSTEM

We assessed the influence of hydropower on the flow characteristics of the river Tay, one of the UK's most heavily regulated catchments and important Atlantic salmon fisheries. Hydropower developments in the mid‐20th century preceded flow data collection, resulting in knowledge gaps over how far regulated flows deviate from natural and how ecosystem functioning might have been impacted. We used 29 unregulated catchments in and around the Tay to assess the relationships between hydroclimatic conditions, landscape structure and the overall flow regime, as well as the annual, monthly and daily flow metrics. This allowed the identification of flow characteristics by using an integrated suite of regression approaches (nonlinear, MLR and random forests) to assess likely impacts at 11 regulated sites. The results showed that the impacts of regulation are highly variable in both space and time. Headwater sub‐catchments are most heavily affected, and water imports or exports as part of hydropower schemes can increase or decrease annual runoff by up to 50%, respectively. On a monthly basis, regulation primarily increased summer low flows; winter high flows increased in catchments affected by water imports and reduced where there was a net water export. At larger catchment scales, impacts were relatively small, as unregulated tributaries re‐naturalize the flows and the effects of intra‐basin transfers balance. Non‐stationarity in climate and water use in the catchment dictates that adaptive management of flows may be necessary to protect ecosystems services. Copyright © 2013 John Wiley & Sons, Ltd.     

Including environmental flow requirements as part of real‐time water resource management

South African water resources legislation requires that environmental flow requirements are included as part of water resource management. An operational management method is presented that relies upon simulating natural flow conditions based on inputs of near real‐time observations of rainfall and a set of operating rules. The operating rules define the reservoir releases and water use supply curtailments that ensure downstream environmental flow objectives will be met. The focus is on managing the variability of continuous low flows, while a suitable method for managing event‐based high flow releases remains elusive. The main limitation to the successful implementation of the low flow approach is the lack of legislated control over run‐of‐river water abstractions. While this limitation is expected to be overcome, as the provisions of new legislation are implemented, water managers may still lack the capacity to exercise the necessary controls over abstraction. There is no reason why the method could not be applied outside South Africa, given compatibility in the definition of environmental flow requirements. Copyright © 2008 John Wiley & Sons, Ltd.     

Ecological perspectives on regulation and water allocation for the Ord River,Western Australia

Water management agencies throughout Australia are attempting to find a balance between the water requirements of ecological and socio‐economic environments as part of a holistic approach to managing flow‐dependent river ecosystems. Environmental water provisions are under consideration for the Ord River in far northern Western Australia. This river has been regulated for irrigation and there are plans for substantial expansion. Like other semi‐arid and tropical rivers, however, the hydrology of the Ord River is highly variable and unpredictable, and therefore, proportionate water release strategies for the environment that are based on average monthly flows are unsuitable. Regulation continues to produce pronounced ecological changes throughout the river system as the impacts of flow regime are negated. There is a dichotomy in optimal flow regimes for the contrasting management aspirations of ecological restoration based on low seasonal flows, and the dilution flows required for the drainage of agricultural effluent. Whilst current agricultural land and water management practices continue, the two cannot coincide, and consequently, a decision should be made regarding which environmental water allocation holds the primary value. Such a decision would guide the appropriate dry season flow regime on the lower Ord River. Copyright © 2002 John Wiley & Sons, Ltd.     

Establishing Environmental Water Requirements for the Murray–Darling Basin,Australia's Largest Developed River System

There is a global need for management of river flows to be informed by science to protect and restore biodiversity and ecological function while maintaining water supply for human needs. However, a lack of data at large scales presents a substantial challenge to developing a scientifically robust approach to flow management that can be applied at a basin and valley scale. In most large systems, only a small number of aquatic ecosystems have been well enough studied to reliably describe their environmental water requirements. The umbrella environmental asset (UEA) approach uses environmental water requirements developed for information‐rich areas to represent the water requirements of a broader river reach or valley. We illustrate this approach in the Murray–Darling Basin (MDB) in eastern Australia, which was recently subject to a substantial revision of water management arrangements. The MDB is more than 1 million km² with 18 main river valleys and many thousands of aquatic ecosystems. Detailed eco‐hydrologic assessments of environmental water requirements that focused on the overbank, bankfull and fresh components of the flow regime were undertaken at a total of 24 UEA sites across the MDB. Flow needs (e.g. flow magnitude, duration, frequency and timing) were established for each UEA to meet the needs of key ecosystem components (e.g. vegetation, birds and fish). Those flow needs were then combined with other analyses to determine sustainable diversion limits across the basin. The UEA approach to identifying environmental water requirements is a robust, science‐based and fit‐for‐purpose approach to determining water requirements for large river basins in the absence of complete ecological knowledge. © 2015 The Authors. River Research and Applications published by John Wiley & Sons, Ltd.     

Operationalizing the allocation of environmental flows: A U.K. perspective on Baxter's Schedule

Early attempts to gauge streams were used by George Baxter in 1961 to propose a pioneering scheme for deriving and allocating water for what today may be recognized as environmental flows in the United Kingdom, but the approach was not accepted into practice. A fundamental concern was the quality of river flow data. Stream gauging was advanced by the 1963 Water Resources Act, and prior to this, the allocation of water resources to compensation flows below dams was based on the basic principle of one third of the reliable yield, estimated using rainfall data. Despite the increased availability of river flow data since the 1970s, it is suggested that low‐flow data quality has severely constrained the management and allocation of water resources and remains so today. Today, pressures and demands on water resources are increasing, but the accuracy of low‐flow measurement is still hindering the operational determination and implementation of environmentally robust, seasonally variable environmental flows. Successful river regulation and restoration relate to a complex suite of public policy questions and given uncertainty over the quality of low‐flow data, transparent, pragmatic decisions about societal allocations of water need to be made.