The basic flow method for incorporating flow variability in environmental flows

The Basic Flow is a methodology used to calculate environmental flow needs for river regulation. It has gained increased recognition in Spain for hydrological planning. It is based on the study of irregularities in hydrological series of daily mean flows using the simple moving average model as a tool to extract the relevant information. The Basic Flow Methodology (BFM), beyond providing a unique minimum flow value, constitutes a complex management proposal for regulated rivers which includes other management aspects affecting the biological functioning of a river (such as the necessity of flow variability, bankfull flows or varying flow rates) through the establishment of monthly instream flow requirements. This paper presents a practical application of the BFM in the Silvan stream, a natural mountain stream impacted by a hydroelectric regulation project. Results are discussed in terms of physical habitat created and compared to those obtained from the application of another method based on the Instream Flow Incremental Methodology, using a set of computer programs (RHYHABSIM) for physical habitat simulation. Copyright © 2010 John Wiley & Sons, Ltd.     

A functional flows approach to selecting ecologically relevant flow metrics for environmental flow applications

The science and practice of environmental flows have advanced significantly over the last several decades. Most environmental flow approaches require quantifying the relationships between hydrologic change and biologic response, but this can be challenging to determine and implement due to high data requirements, limited transferability, and the abundance of hydrologic metrics available for evaluation. We suggest that a functional flows approach, focusing on elements of the natural flow regime known to sustain important ecosystem processes, offers a pathway for linking understanding of ecosystem processes with discrete, quantifiable measures of the flow regime for a broad range of native taxa and assemblages. Functional flow components can be identified as distinct aspects of the annual hydrograph that support key biophysical processes, such as wet season flood flows or spring recession flows, and then quantified by flow metrics, such as 5% exceedance flow or daily percent decrease in flow, respectively. By selecting a discrete set of flow metrics that measure key functional flow components, the spatial and temporal complexity of flow regimes can be managed in a holistic manner supportive of multiple ecological processes and native aquatic species requirements. We provide an overview of the functional flows approach to selecting a defined set of flow metrics and illustrate its application in two seasonally variable stream systems. We further discuss how a functional flows approach can be utilized as a conceptual model both within and outside of existing environmental flow frameworks to guide consideration of ecological processes when designing prescribed flow regimes.     

河道生态环境需水研究方法比较

对近年来的河道生态环境需水研究方法进行了回顾和分析，包括水文学法、水力学法、水文—生物分析法、生境模拟法、综合法以及作者参与研究的环境功能设定法等。文章对这些方法的理论基础、优缺点、适用范围进行了重点研究和评述，并结合我国情况分析了其在国内的应用前景。认为水文学法、生境模拟法、综合法和环境功能设定法相对来说都较适合于我国研究，其中生境模拟法由于实施比较复杂，应用性受到一定的限制。     

Effects of Environmental Water Transfers on Stream Temperatures

Low streamflows and warm stream temperatures currently limit habitat and productivity of trout, including native Lahontan cutthroat trout in Nevada's Walker Basin. Environmental water transfers, which market water from willing sellers to instream uses, are evaluated to improve instream habitat. We use River Modelling System, an hourly, one‐dimensional hydrodynamic and water quality model, to estimate current and potential environmental water transfer effects on stream temperatures. Model runs simulate a range of environmental water transfers, from 0.14 to 1.41 cms, at diversions and reservoirs for wet year 2011 and dry year 2012. Results indicate that critically warm stream temperatures generally coincide with low flows, and thermal refugia exist in East Walker River, a tributary of the Walker River. Environmental water transfers reduce maximum stream temperatures by up to 3 °C in dry years and are more effective in dry years than wet years. This research suggests that environmental water transfers can enhance instream habitat by improving water quality as well as increasing instream flow. Copyright © 2015 John Wiley & Sons, Ltd.     

Unclogging improvement based on interdate and interreach comparison of water release monitoring (Durance,France)

Large‐scale flow release experiments are becoming common for improving aquatic habitat quality downstream of dams. Because of the naturally high fine sediment load in the Durance River, France due to inputs from torrential tributaries draining badlands, unpredictable high flow events with dam overspill are not always sufficient to prevent clogging, which can lead to habitat degradation (especially spawning habitats) in bypassed reaches. Therefore, large‐scale flow experiments were conducted on four reaches to test the efficacy of clear‐water releases to improve aquatic habitat conditions. Continuous measurements of water depth, suspended sediment concentrations, and turbidity were conducted during twelve releases and compared on nine. Before and after each release, superficial clogging was measured. The study shows that there is a link between the volume of suspended sediments carried by water releases and the initial clogging. The volumes carried were low compared with the river's annual transport. The effect on clogging can vary significantly from one release to another. In particular, the hydrological context surrounding the releases has a significant influence on clogging. Comparisons of monitoring showed that releases are more effective on reaches that are more severely regulated (high hydrological control) than on those that are less well‐controlled. The areas with the highest initial clogging tend to unclog more than those with lower initial clogging; however, the latter zones are most impacted by ineffective releases. Performing a release on environments with low initial clogging can therefore be environmentally damaging. To ensure that releases are successful and that intervention is warranted, initial clogging should be measured in the field and releases should only be performed if the clogging is judged to be unfavourable.     

Flow and water temperature simulation for habitat restoration in the Shasta River,California

Low instream flows and high water temperatures are two factors limiting survival of native salmon in California's Shasta River. This study examines the potential to improve fish habitat conditions by better managing water quantity and quality using flow and water temperature simulation to evaluate potential restoration alternatives. This analysis provides a reasonable estimate of current and potential flows and temperatures for a representative dry year (2001) in the Shasta River, California. Results suggest restoring and protecting cool spring‐fed sources provides the most benefit for native salmon species from a broad range of restoration alternatives. Implementing a combination of restoration alternatives further improves instream habitat. Results also indicate that substituting higher quality water can sometimes benefit native species without increasing environmental water allocations. This study shows the importance of focusing on the limitations of specific river systems, rather than systematically increasing instream flow as a one size fits all restoration approach. Copyright © 2009 John Wiley & Sons, Ltd.     

A PRESUMPTIVE STANDARD FOR ENVIRONMENTAL FLOW PROTECTION

The vast majority of the world's rivers are now being tapped for their water supplies, yet only a tiny fraction of these rivers are protected by any sort of environmental flow standard. While important advances have been made in reducing the cost and time required to determine the environmental flow needs of both individual rivers and types of rivers in specific geographies, it is highly unlikely that such approaches will be applied to all, or even most, rivers within the forseeable future. As a result, the vast majority of the planet's rivers remain vulnerable to exploitation without limits. Clearly, there is great need for adoption of a “presumptive standard” that can fill this gap. In this paper we present such a presumptive standard, based on the Sustainability Boundary Approach of Richter (2009) which involves restricting hydrologic alterations to within a percentage‐based range around natural or historic flow variability. We also discuss water management implications in applying our standard. Our presumptive standard is intended for application only where detailed scientific assessments of environmental flow needs cannot be undertaken in the near term. Copyright © 2011 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.     

A geomorphic monitoring and adaptive assessment framework to assess the effect of lowland floodplain river restoration on channel–floodplain sediment continuity

The state of the science of lowland river floodplain restoration reflects the relatively new and experimental nature of large river floodplain rehabilitation efforts. Based on results of a case study of floodplain restoration at the lowland Cosumnes River, California, we present a geomorphic monitoring and adaptive assessment framework that addresses the need to inform and utilize scientific knowledge in lowland floodplain river restoration activities. Highlighting hydrogeomorphic processes that lead to habitat creation, we identify a discharge threshold for connectivity and sediment transfer from the channel to the floodplain and integrate discharge magnitude and duration to quantify a threshold to aid determination of when geomorphic monitoring is warranted. Using floodplain sand deposition volume in splay complexes as one indicator of dynamic floodplain habitat, we develop a model to aid prediction of the sand deposition volume as an assessment tool to use to analyze future monitoring data. Because geomorphic processes that form the physical structure of a habitat are dynamic, and because the most successful restoration projects accommodate this fundamental characteristic of ecosystems, monitoring designs must both identify trends and be adapted iteratively so that relevant features continue to be measured. Thus, in this paper, adaptive assessment is defined as the modification of monitoring and analysis methods as a dynamic system evolves following restoration activities. The adaptive monitoring and assessment methods proposed facilitate long‐term measurements of channel–floodplain sediment transfer, and changes in sediment storage and morphology unique to lowland river–floodplain interactions and the habitat that these physical processes support. The adaptive assessment framework should be integrated with biological and chemical elements of an interdisciplinary ecosystem monitoring program to answer research hypotheses and to advance restoration science in lowland floodplain river systems. Copyright © 2005 John Wiley & Sons, Ltd.     

Reservoir system management and environmental flows

Considerable attention has been paid to the downstream effects of reservoirs on the ecology of rivers, streams and wetlands. However, most reservoirs were constructed well before ecological concerns became prominent. Little attention has been given to the question of what extent existing structures and management systems can accommodate changes. The paper discusses this matter and a range of associated issues. It is concluded that many problems can be rectified by structural means but that such rectification will be very expensive. While based primarily on Australian systems, the conclusions and examination are considered to be globally applicable.     

Monitoring of environmental flow outcomes in a large river basin: The Commonwealth Environmental Water Holder's long‐term intervention in the Murray–Darling Basin,Australia

The Murray–Darling Basin in south‐eastern Australia contains over 70,000 km² of wetlands and floodplains, many of which are in poor condition. In response, Australian governments have committed to a major restoration program, the Murray–Darling Basin Plan that includes management of 2,750 Gl of environmental water to protect and restore aquatic ecosystems. The restoration is being undertaken within an adaptive management framework that includes monitoring the outcomes of environmental flows in seven river valleys. This paper provides an overview of the 5‐year monitoring project and some preliminary results. Monitoring design considered the Basin Plan's environmental objectives, conceptual models of ecosystem responses to flow, and an outcomes framework linking flow responses to the environmental objectives. Monitoring indicators includes ecosystem type, vegetation, river metabolism, and fish. Responses are evaluated to identify the contribution of environmental flows to Basin Plan environmental objectives and continual improvements in management. The program is unique in that it seeks to monitor long‐term outcomes of environmental flows at the river basin scale. Despite many challenges, the monitoring has become a key part of the adaptive management of environmental flows in the Murray–Darling Basin.     

一种变参数目适应流量演算法及应用

本文建立了一变参数自适应流量演算法以求非线性解或准线性解，提出了模型的参数识别法，并利用假设检验确定模型阶数ｎ．最后用实际算例进行了验证     

塔里木灌区引水前后环境流特性变化

基于水文改变指标基本分析方法,筛选建立了环境流评价指标,着重分析了塔里木灌区引水对塔里木河干流阿拉尔和新渠满断面环境流变化的影响。结果表明:在灌区大量引水灌溉前后,干流两个主要水文站的环境流组成分别呈现出不同程度的变化,环境流组成趋于单一化;各水文站的流量事件以枯水流量事件为主;引水对特枯流量事件、高流量脉冲事件和大洪水事件的影响较大。结合环境流指标和生态系统响应关系,制定了面向生态的水资源优化调度方案,为流域生态治理和水量分配提供了参考。     

流域环境流量管理分区方法研究——以浑河流域为例

环境流量管理分区对识别流域各地区的环境流量管理要求,合理配置河流环境流量,协调社会-生态竞争性用水具有重大意义。本文结合管理结构体系,统筹考虑社会-自然两大属性,构建流域分区指标体系;利用聚类分析算法以及布尔运算法结合指标体系对管理流域进行划分,建立了一种区划管理分区的方法。以浑河流域为例,按划分方法将浑河流域划分为5个环境流量管理分区。结果表明:分区方法切实可行,利于简化流域整体管理复杂程度;每个分区具有独立完整的管理结构体系;环境流量管理分区特征鲜明,利于各区管理目标的制定。     

山西汾河复流前后水环境承载能力分析

在对汾河水质、入河排污量监测的基础上,选取计算模型及相关参数,以掌握汾河复流前后水环境承载能力为主要目的,以各水功能区为基本计算单元,分析计算水功能区不同来水条件下的水域纳污能力,进而提出汾河复流后各行政分区的污染物限排总量及污染物削减率。结果表明:复流后各功能区COD和NH3-N限制排污总量分别为25 139 t/a和1 158 t/a,污染物削减量分别为24 704t/a和7 857 t/a,平均削减率分别为49.6%和87.2%。若各入河排污口达标排放后,COD、NH3-N仍要削减15 936 t/a和4 356 t/a。     

浙江兰溪东芝灌区河道环境需水量的分析与计算

在东芝灌区节水配套改造工程规划设计中,将河道环境需水量纳入水量平衡计算中,并在传统的Tennant法的基础上进行改进,根据实际河道水文特征周期来修正Tennant法的汛期和非汛期;采用典型年逐旬径流量修正Tennant法汛期、非汛期河道环境需水量,在满足必需的河道环境需水量的基础上,减少灌区不必要的弃水。     

Reflexive learning in adaptive management: A case study of environmental water management in the Murray Darling Basin,Australia

Adaptive management is a structured approach for people who must act despite uncertainty and complexity about what they are managing and the impacts of their actions. It is learning‐by‐doing through deliberate cycles of experimentation, review, and synthesis. However, understanding the processes of learning and how they relate to achieving resource management goals is in its infancy. Reflexive learning—a process of identifying and critically examining assumptions, values, and actions that frame knowledge—is critical to the effectiveness of adaptive management. It involves adaptive feedbacks between stakeholders as they examine assumptions, values, and actions. Adaptive management has been applied to environmental flows because it offers a system for making decisions about tradeoffs. In the Murray Darling Basin (MDB), Australia, adaptive management is applied as a cycle of plan, do, monitor, and learn, facilitated by short‐ and long‐term learning among stakeholders. An alternative conceptualization of adaptive management as an integration of single‐, double‐, and triple‐loop learning across multiple levels of governance is presented. This is applied to environmental flows in the MDB to map adaptive feedbacks of reflexive learning. At the lowest level of governance (Water Resource Planning Area), goals are assessed as Thresholds of Potential Concern related to flow‐ecology responses, which are reviewed every 3–6 years. At the second level of governance (Basin‐States), Water Management Targets are the key goals; reviewed and reframed every 6–10 years. The highest level of governance (the MDB) is concerned with policy targets, with review and reframing over 8–15 years. Feedbacks that generate reflexive learning are complex and require commitment to move through the modes of single‐, double‐, and triple‐loop learning. Effective adaptive management of environmental water requires practitioners to situate themselves within a matrix of information flow across modes of learning, levels of governance, and components of a social‐ecological system, where reflexive learning drives the achievement of management goals.     

A Twofold Strategy for Riparian Restoration: Combining a Functional Flow Regime and Direct Seeding to Re‐establish Cottonwoods

The transboundary St Mary River drains Glacier National Park, USA, and was progressively dammed and diverted over the 20th century to support agricultural irrigation in northern Montana and southern Alberta, Canada. Following reduced instream flows, the riparian cottonwoods collapsed, and by 2000, few parental trees remained to provide seeds for cottonwood replenishment. As a novel twofold restoration strategy we: (1) worked with the dam operators to deliver a functional flow regime, a regulated instream flow pattern intended to recover some ecological function and specifically seedling recruitment, and (2) delivered cottonwood seeds by direct spreading and by sticking cuttings with seed catkins to allow gradual seed dispersal. The combination of river regulation and seeding enabled cottonwood colonization, and around 1.5% of the applied seeds produced seedlings after the first summer, at sites without livestock or heavy recreational use. Around 15% of those seedlings survived through the fourth summer, with mortality due to drought stress and flood scour, and establishment and survival were higher for the prairie cottonwood, Populus deltoides, than the narrowleaf cottonwood, Populus angustifolia. This study confirmed that the lack of seed source trees limited cottonwood colonization and demonstrated that the twofold restoration strategy provides promise for severe situations where parental trees have been lost. However, this would require substantial effort, and it would be more efficient to provide survivable instream flow patterns that avoid cottonwood collapse. Copyright © 2015 John Wiley & Sons, Ltd.     

Flavia Rocha Loures and Alistair Rieu-Clarke (eds), The UN Watercourses Convention in force: strengthening international law for transboundary water management

Abstract

The MODSIM 8.0 decision support system (DSS) for integrated river basin management (IRBM) has been adapted from a prior appropriation rights-based system to one found in Korea and in much of Asia where water deficits are shared among water use sectors, taking into account priorities established by water policy and institutional frameworks. The Korean version called KModSim is applied to the Geum River basin for evaluation of long-term sustainability of existing and new water infrastructure and facilities under integrated, basin-wide water resources management. KModSim is calibrated to the physical and hydrologic characteristics of the basin, as well as to operational and administrative water allocation policies for municipal and industrial water supply, irrigation, hydropower, transbasin diversions, and low-flow augmentation for environmental purposes. Conditional reservoir operational rules that adapt to changing river basin hydrologic conditions are developed from an implicit stochastic optimization algorithm and incorporated using the extensive user-customization capabilities of KModSim. Results demonstrate that decision guidance under KModSim enhances beneficial water uses in the Geum River system through fully integrated, basin-wide management.