下游河道对流量变化响应法的研究理论及进展

为探究当前环境流量的研究进展及发展方向,补充环境流量评估方面的研究方法,概述了国内外环境流量研究进展,应用CiteSpace软件结合中国知网与Web of Science数据库分析环境流量研究方法在21世纪以来的历史热点及主题演变情况。从开发背景、模型模块及应用步骤等方面详细介绍了一种用于环境流量评估的整体法——下游河道对流量变化响应法DRIFT(Downstream Response to Imposed Flow Transformation),结合南非奥卡万戈河以及赞比西河工程案例总结了该方法在环境流量评估及生态系统保护研究方面的应用,为环境流量研究提供新的思路与方法。     

How much groundwater can we pump and protect environmental flows through time? Presumptive standards for conjunctive management of aquifers and rivers

Groundwater is a critically important source of water for river, wetland, lake, and terrestrial ecosystems, yet most frameworks for assessing environmental flows have ignored or not explicitly included the potential impacts of groundwater pumping on environmental flows. After assessing the processes and existing policies for protecting streamflow depletion from groundwater pumping, we argue that a new groundwater presumptive standard is critical as a placeholder to protect environmental flows in rivers lacking detailed assessments. We thus extend the previous presumptive standard to groundwater pumping, a different and important driver of changes to streamflow. We suggest that “high levels of ecological protection will be provided if groundwater pumping decreases monthly natural baseflow by less than 10% through time.” The presumptive standard is intended to be a critical placeholder only where detailed scientific assessments of environmental flow needs cannot be undertaken in the near term. We also suggest a new metric, the environmental flow response time, that allows water managers to quantify the timescales of the impacts of groundwater pumping on the loss or gain of environmental flows.     

环境流量评估法-结构单元法的工作框架和内涵

为了弥补中国现有环境流量评估方法仅将重点放在特定目标物种上的不足,详细介绍了一种用于评估环境流量的整体法——结构单元法(Building Block Methodology,BBM)。该方法依照科学基础和实际需要将整个研究区域的研究对象和影响因素准确划分为不同“块”,然后探寻各个不同影响因素的“块”与每一个研究对象之间关系,最后对整个研究区域拟定一个合理的环境流量方案。其工作步骤主要分为3个部分:①研讨会前收集基础资料;②研讨会期间各学科专家对自己收集的资料进行相应的解释、讨论,最终就推荐的环境流量达成共识;③研讨会后生成流量修改的方案,并制定监测计划。并结合印度的Sri Ram Sagar水库和挪威的Daleeleva河的应用实例分析了该方法的特点和存在的不足之处。该方法能更好地保证环境流量确定过程中河流生态价值和服务价值,为其在中国的应用提供借鉴。     

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.     

A hydrogeomorphic dynamics approach to assess in‐stream ecological functionality using the functional flows model,part 1—model characteristics

The functional flows model integrates hydrogeomorphic processes and ecological functions for stream physical habitat evaluations. Functional flows are discharge values that serve ecological uses. Assessments of functional flows are based on evaluation of shear stress dynamics. The analysis is based on the occurrence of sediment transport regimes defined by threshold values of Shields stress estimated from discharge (Q), a parameter (f) governing depth response to incremental discharge changes, water surface slope (S) and media grain size (D₅₀). As an example, the model was tuned for fall‐run Chinook salmon spawning. Ecological functions studied were bed occupation (spawning, incubation and emergence) and bed preparation (river bed reworking periods)—both reliant on shear stress dynamics. A numerical experiment and sensitivity analysis using a wide range of realistic values of input variables indicated the effect of each variable on flow functionality. Combinations of S = 0.001, 0.005 and 0.01, D₅₀ = 0.02, 0.05, 0.1 m, f = 0.2, 0.3, 0.4, 0.5 and four sediment transport stages produced 144 scenarios. Ranges of functional flows were greater for scenarios for low f (0.2) with low slope (0.001,0.05), for high f (0.5) with small grain size (0.02 m) and for intermediate low f (0.3) with coarse grain size (0.1 m). The functional flows model incorporates in‐stream habitat processes by including metrics of hydrologic, hydraulic, geomorphic and ecologic dynamics. Model uncertainties related to input data, calculation algorithms, and model structure are analysed. Functional flows analysis can be useful in studying water management alternatives to improve habitat conditions for target species and lifestages. Copyright © 2009 John Wiley & Sons, Ltd.