State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing, 210098, China.
College of Hydrology and Water Resources, Hohai University, Nanjing, 210098, China.
Environ Monit Assess. 2018 Jul 7;190(8):453. doi: 10.1007/s10661-018-6825-x.
Hydrologic regimes are essential to riverine, lacustrine, and wetland ecosystems, and every component of a hydrologic regime has a specific ecological environmental function. In an outflow lake-river system, water levels are reduced by a reservoir constructed at the river, which interferes with the river-lake interrelationships by impairing the river's blocking effect. This increases the lake-river hydraulic gradient and accelerates the lake's drainage to the river, resulting in shrinkage of the lake and damaging environmental issues. To respond to these issues, we propose an environmental flow assessment that considers the river's blocking effect on the lake. This novel methodology consists of four steps: data preparation, assessment of the lake's environmental water level, assessment of the river's environmental water level, and environmental flow assessment. We estimated the river's environmental water level through a hydraulic correlation between the lake and the river, and found that the river's blocking effect could be sustained. The Yangtze-Poyang system was selected as a case study to illustrate the methodology's procedures and applicability. The impoundment of the Three Gorges Reservoir, during the fall retreating season, decreased the Yangtze's water level and weakened the Yangtze's blocking effect on Poyang Lake. Poyang Lake's environmental water level, which ranges from 11.71 to 15.81 m in the month of October, was used to estimate the Yangtze's environmental water level as falling in a range of 11.95 to 16.17 m, which corresponds to an environmental flow range of 16,822 to 32,371 m/s. This study offers a solution for reservoir-induced accelerated lake drainage, which may be helpful in mitigating the negative impacts of reservoirs and sustaining natural rive-lake interactions.
水文学的模式对河流、湖泊和湿地生态系统至关重要，水文学模式的每一个组成部分都有其特定的生态环境功能。在一个流出型湖泊-河流系统中，河流上建造的水库会降低水位，通过削弱河流的阻断效应干扰河-湖相互关系。这会增加湖泊-河流水力梯度，并加速湖泊向河流排水，导致湖泊缩小和环境破坏等问题。为了应对这些问题，我们提出了一种考虑河流对湖泊的阻断效应的环境流量评估方法。这种新方法包括四个步骤：数据准备、湖泊环境水位评估、河流环境水位评估和环境流量评估。我们通过湖泊与河流之间的水力关系来估计河流的环境水位，并发现河流的阻断效应可以得到维持。选择长江-鄱阳湖系统作为案例研究，说明了该方法的程序和适用性。三峡水库在秋季退水期间蓄水，降低了长江水位，削弱了长江对鄱阳湖的阻断效应。鄱阳湖的环境水位在 10 月份的 11.71 至 15.81 米之间，我们利用这一数据来估计长江的环境水位，结果显示长江的环境水位在 11.95 至 16.17 米之间，对应的环境流量范围为 16822 至 32371 立方米/秒。本研究为水库诱发的加速湖泊排水问题提供了解决方案，有助于减轻水库的负面影响，维持自然的河-湖相互作用。
