水电开发影响下河流生境序列变化及生物多样性保育机制研究

Located at the intersection of Dadu River, Qingyi River and Minjiang River, Angu hydropower station is characterized with typical features of the plateau estuarine wetland, and it is the important 'three-field' distribution area of fishes in the downstream of Dadu River. The hydropower development and construction changes the spatial and temporal distribution of the hydraulic characteristic of the river artificially, which further changes the material field, energy field, chemical field and biological field, leads to the variations in the diversity of organisms in the river. The research contents of this project are mainly shown as follows: (I) On the basis of multi-temporal high-resolution remote-sensing image, hydro meteorology and terrain, the dynamic varying characteristic of the river's habitat sequence variation is analyzed by combining the historical data and status ground survey to reveal the dynamic evolution process of the rivers and wetland in regions of Angu hydropower station and to evaluate the corresponding ecosystem function of wetland of different habitats. (II) Establish a statistical relation for the biodiversity index and factors of different habitats, make use of multi-element statistical analysis method to analyze the changes in climate and hydrology of different stages, as well as the changes in the terrain and land use methods caused by human activities, study the influence of these changes on the biodiversity, reveal the key habitat factor influencing the preservation of biodiversity and distinguish the key ecological process for the preservation of biodiversity (especially the flagship species). (III) Establish a plane two-dimension hydrological dynamic model to study the changes of hydrologic process and process of sedimentation caused by the power station construction and to simulate the changes of stream flow regime in different situations. On that basis, conduct the refined simulation of the flow structure in key reach, such as the typical wetland and spawning site of fishes to analyze the influence of hydropower development on the water level variation, depth of water, flow field, etc. and carry out the predications on the variations in the habitats. (IV) Select the damaged key habitat factor under the hydropower development to study and establish the health evaluation index system for the habitat recovery. On the basis of studying the relevance between the biodiversity and habitat factor, it carries out the situational analysis for the direct and indirect influence on the biodiversity after the habitat changes to distinguish the potential key site of the habitat damage and biodiversity threats in the wetland. This project study provides theoretical basis and scientific support for learning about, evaluating and recovering the influence the water conservancy project on the ecological environment, thus to guarantee the sustainable development of the water-power engineering in China.

安谷水电站地处大渡河、青衣江、岷江的三江交汇口，具备典型的高原河口湿地特征，是大渡河下游重要的鱼类"三场"分布区。水电开发建设改变了原有河流型湿地生态系统的水文状况，对区域湿地生物多样性带来了显著影响。本研究针对区域生态系统特点，通过分析河流生境序列的动态变化特征，揭示安谷电站区域河流湿地动态演变过程，并对不同生境所对应的湿地生态功能进行评估；建立生物多样性与关键生境因子间的统计关系，辨析关键生境因子对生物多样性的影响，揭示生物多样性保育的关键生态过程；建立水文水动力模型，预测安谷水电开发影响下河流生境变化情景及其水文与水生态演变趋势；分析安谷电站开发下生物多样性所受影响，辨识生境及生物多样性受损关键位点。通过该项目研究，为客观认识、评价及修复水利工程建设对生态环境影响提供理论依据和科学支撑，从而确保我国水电工程可持续发展。

水利水电工程建设在带来巨大的经济和社会效益的同时，也剧烈地改变了原有河流型湿地生态系统的水文状况，建造大坝阻断了河流，引起生境的破碎化等一系列情形都对湿地生态系统带来了显著影响。如何在开发中保护、在保护中开发是水电工程建设必须正视并得以解决的关键问题。 . 安谷水电站地处大渡河、青衣江、岷江的三江交汇口，具备典型的高原河口湿地特征，是大渡河下游重要的鱼类“三场”分布区。由于地处河流系统相互联系、相互作用和相互影响的交接过渡地带，具有生物多样性丰富、受人类干扰频繁、生态环境脆弱等生态特征。. 本研究针对区域湿地生态系统特点，通过对动植物区系、底泥、水质等生态系统特征进行详细调查，阐明每种生境类型所对应的生态系统组成和结构，并对其生态系统功能进行评估。在此基础上，针对工程建设特点，对湿地空间结构变化、湿地功能影响方面进行定性分析，并进行综合评价。. 基于水沙原型观测资料，建立一维水文水动力模型，研究电站建设对水文过程的改变，模拟不同情景下水流状态的变化。在此基础上，结合平面二维水文水动力模型，开展典型湿地、鱼类产卵场等重点河段水流结构的精细模拟，分析水电开发对水位变动、水深、流场等的影响，并对由此导致的生境条件变化进行研究。基于以上研究成果，提出了包括下泄生态流量、鱼类重要生境和栖息地保护营造、河道生态修复、重要湿地节点保护以及修复典型设计在内的系列工程措施。. 通过该项目研究，为客观认识、评价及修复水利工程建设对生态环境影响提供理论依据和科学支撑，从而确保我国水电工程可持续发展。