梯级水库作用下卵石河床微地貌演变及其对珍稀鱼类产卵场的影响研究

Reservoir has made the natural river into a state of river-reservoir-river. With the development of hydroelectric stations, river in the downstream of dams has been affected, including flow and sediment process, landform, which would affect ecological system of the river and hydrophily biology. So far, a lot of studies about impact of dam construction on characteristics of water and sediment transportation on downstream river, however, studies on microtopography of gravel bed and interaction effect between it and spawning ground of rare fish under the action of cascade hydropower are lacking. In view of this, the project will carry out analysis of long time series and space in a typical river branch, which affected directly by cascade hydropower development, based on observed data, field monitoring and numerical simulation. Rare fish are used as good indicators of changes about river ecological environment. The contents of the study are as follows: the influence of cascade reservoir on ecohydrological process; the evolution characteristics of microtopography of gravel bed in the process of cascade reservoir; the effect of cascade reservoir to adaptive condition of rare fish spawning ground. Ultimately, the adjustment characteristics of microtopography of gravel bed under the effect of erosion by clear water will be illuminated. The research deals with the interdiscipline of River Dynamics, Riverbed Evolution and Freshwater Ecology, and provides scientific base for protection of rare fish in the upstream of Yangtze River.

水库改变下游河道水文过程及水沙输移特性，引起河道地貌形态的调整，进而对水生生物产生影响。国内外围绕梯级水库对下游河流水沙输移特性的影响开展了大量研究，而关于梯级水库对卵石河床微地貌演变及其与鱼类产卵场的相互影响研究匮乏。鉴于此，项目拟选取受梯级水库影响最直接的向家坝至朱沱段，基于长时间序列的实测资料分析、野外现场调查与监测和数值模拟手段，以珍稀鱼类保护为出发点，从水文、泥沙及生境累积效应角度，研究梯级水库对生态水文过程的影响、梯级水库建设进程中卵石河床微地貌调整与响应规律和珍稀鱼类产卵场适应性变化。通过上述研究，阐明梯级水库开发对珍稀鱼类产卵场地貌形态及水动力条件的影响，提出适宜达氏鲟、胭脂鱼产卵的生态调度方案和产卵场保护建议。项目属于河床演变学与水生态学等学科的交叉融合，成果可为长江上游珍稀鱼类保护提供科学依据。

水库改变下游河道水文过程及水沙输移特性，引起河道地貌形态的调整，进而对水生生物产生影响。国内外围绕梯级水库对下游河流水沙输移特性的影响开展了大量研究，而关于梯级水库对卵石河床微地貌演变及其与鱼类产卵场的相互影响研究匮乏。针对这一现状，本项目以长江上游珍稀特有鱼类国家级自然保护区干流河段为研究范围，采用现场调查与监测、实测资料分析等方法，分析不同时间段保护区河段水文过程变化特点，研究梯级水库建设对保护区水文情势的影响；以重点产卵江段安边镇河段和李庄镇河段为例，研究梯级水库蓄水对产卵场局部微地貌的影响；在此基础上，评估了梯级水库建设对保护区鱼类产卵的影响，提出了保护区产卵场修复的建议方案。研究成果促进了学科交叉，可为后续梯级水库生态调度及保护区鱼类产卵场修复提供理论依据，成果已在《长江上游干流宜宾以下河道采砂管理规划报告（2020-2025年）》编制中得到应用，为保护区内采砂管理提供技术支撑，有着重要的实际价值。