College of Water Sciences, Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology, Beijing Normal University, Beijing, 100875, PR China.
School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, PR China.
Water Res. 2018 Sep 15;141:96-108. doi: 10.1016/j.watres.2018.05.025. Epub 2018 May 15.
The survival of aquatic biota in stream ecosystems depends on both water quantity and quality, and is particularly susceptible to degraded water quality in regulated rivers. Maintenance of environmental flows (e-flows) for aquatic biota with optimum water quantity and quality is essential for sustainable ecosystem services, especially in developing regions with insufficient stream monitoring of hydrology, water quality and aquatic biota. Few e-flow methods are available that closely link aquatic biota tolerances to pollutant concentrations in a simple and practical manner. In this paper a new method was proposed to assess e-flows that aimed to satisfy the requirements of aquatic biota for both the quantity and quality of the streamflow by linking fish tolerances to water quality criteria, or the allowable concentration of pollutants. For better operation of water projects and control of pollutants discharged into streams, this paper presented two coefficients for streamflow adjustment and pollutant control. Assessment of e-flows in the Wei River, the largest tributary of the Yellow River, shows that streamflow in dry seasons failed to meet e-flow requirements. Pollutant influx exerted a large pressure on the aquatic ecosystem, with pollutant concentrations much higher than that of the fish tolerance thresholds. We found that both flow velocity and water temperature exerted great influences on the pollutant degradation rate. Flow velocity had a much greater influence on pollutant degradation than did the standard deviation of flow velocity. This study provides new methods to closely link the tolerance of aquatic biota to water quality criteria for e-flow assessment. The recommended coefficients for streamflow adjustment and pollutant control, to dynamically regulate streamflow and control pollutant discharge, are helpful for river management and ecosystems rehabilitation. The relatively low data requirement also makes the method easy to use efficiently in developing regions, and thus this study has significant implications for managing flows in polluted and regulated rivers worldwide.
水生生物在溪流生态系统中的生存既依赖于水量，也依赖于水质，而在受调控河流中，水质的恶化尤其会对其产生影响。为了维持可持续的生态系统服务，特别是在溪流水文、水质和水生生物监测不足的发展中地区，需要为水生生物提供最佳水量和水质的环境流量（e-flow）。目前，很少有能够以简单实用的方式将水生生物的耐受性与污染物浓度紧密联系起来的 e-flow 方法。本文提出了一种新的 e-flow 评估方法，旨在通过将鱼类对水质标准（或污染物允许浓度）的耐受性与河流流量联系起来，来满足水生生物对水流数量和质量的要求。为了更好地运行水利工程和控制排入溪流的污染物，本文提出了两个用于河流流量调整和污染物控制的系数。对黄河最大支流渭河的 e-flow 评估表明，枯水季节的河流流量未能满足 e-flow 要求。污染物的涌入给水生生态系统带来了巨大压力，污染物浓度远高于鱼类耐受阈值。我们发现流速和水温对污染物降解率都有很大影响。流速对污染物降解的影响远大于流速标准差的影响。本研究为 e-flow 评估中将水生生物的耐受性与水质标准紧密联系起来提供了新方法。建议的河流流量调整和污染物控制系数，用于动态调节河流流量和控制污染物排放，有助于河流管理和生态系统恢复。相对较低的数据要求也使得该方法在发展中地区易于高效使用，因此本研究对管理全球受污染和受调控河流的流量具有重要意义。
