河流水电梯级开发作用下的环境-地貌-生态耦合作用研究

The construction of dams has changed the downstream natural hydrological processes and transport characteristics of water and sediment, furthermore, caused the adjustment of channel morphology and destroyed the original ecological balance. So far, a lot of studies about impact of dam construction on downstream river geomorphology have been conducted, however, studies on coupling mechanism between fluvial processes and ecological processes are lacking. Thus, it impedes a good understanding of integrated river management for the rivers affected by engineering control. In view of this, we plan to carry out field investigations monthly in a typical river branch. Macroinvertebrates are used as good indicators of long-term environmental changes, hydrological and geomorphic processes due to their confinement to the bottom, long life cycles and limited abilities of movement. The contents of this study are as follows: 1) variation of flow-sediment condition and changes of channel micro-geomorphology induced by the construction of dams; 2) temporal-spatial dynamics and regulating factors of macroinvertebrate assemblages; 3) ecological change processes of these indices (habitat suitability, weighted usable area and ecological integrity index). Ultimately, the coupling mechanism between fluvial processes and ecological processes will be revealed. This research deals with the interdiscipline of Fluvial Dynamics, Fluvial Process, and Freshwater Ecology, and is also of great academic values to river development and management.

水坝建设改变了下游自然的水文过程和水沙输移特性，从而引起河道形态的调整，破坏了原有的生态平衡。国内外围绕水坝建设对下游河流地貌的影响开展了大量的研究，而关于河流微地貌演变与水生态过程的耦合机制研究匮乏，这限制了对受水利工程控制的河流开展生态水沙综合管理的认识和理解。鉴于此，本课题拟选择河床微地貌形态年内变化差异较大的典型河段，以对水文条件响应敏感且能指示环境长期变化的河床生物即底栖动物作为指示生物，逐月对水沙条件、河床形态及水生态进行调查，内容包括：1）水坝建设诱发的水沙条件变异和河流微地貌变化；2）底栖动物群落时空动态及调控因子；3）生境适宜度、栖息地可利用面积和生态完整性等指标的生态变化过程。通过综合分析，揭示水坝建设作用下的水沙条件变化、河流微地貌演变与水生态过程耦合作用机制。本课题属河流动力学、河床演变学、淡水生态学等多学科交叉研究，对人类开发、治理和管理河流具有重要的科学价值。

水坝建设改变了下游自然的水文过程和水沙输移特性，从而引起河道形态的调整，破坏了原有的生态平衡。为探明河流水电梯级开发作用下的环境-地貌-生态耦合作用，本项目选取了黄河花园口段及长江武汉段的底栖动物、黄河全段的鱼类、黄河最大支流渭河流域的浮游植物与浮游细菌等多河流、多河段、多指示生物为研究对象，开展河流微地貌演变与水生态过程的耦合机制研究。主要结果有：1) 调查了黄河花园口段及长江武汉段底栖动物的生境条件，发现两个河段中底栖动物的优势类群分别为水生昆虫和寡毛类，并发现生物栖息地可利用面积与流量密切相关；2) 黄河全段水文-水环境-地貌特征及鱼类群落结构时空尺度上变化较为明显，受水电梯级开发影响，黄河上游河段鱼类趋同，下游河段鱼类外来引种和人类干扰较大；3) 渭河流域干支流间生境参数与浮游植物群落结构差异明显，溶氧等和电导率等是分别影响渭河干流与支流浮游植物种类分布和丰度的主要环境因子；4) 构建渭河流域浮游细菌共线网络发现，渭河流域浮游细菌关键物种在干支流上存在空间差异，这反映了干支流间的生境差异性。通过综合分析，揭示梯级水电影响下河流的河床演变特征及水生生物类群的时空变化规律，明晰水坝建设作用下的水沙条件及河流地貌形态与水生态过程耦合作用机制，可为生态水利提供理论和方法基础，为河流生态水沙综合管理提供科学依据。