【作者】 易雨君；

【导师】 王兆印；

【作者基本信息】 清华大学 ， 水利工程， 2008， 博士

【摘要】 水利工程在防洪、发电、灌溉等方面发挥着举足轻重的作用,是人类改造自然、利用自然的一大创举;同时,水利工程建设和运行给生态环境带来的不利影响也引起了社会越来越多的关注。通过统计分析、野外调查及数值模拟等手段,探索了水利工程建设对长江鱼类的影响,主要研究成果包括:1)从河道栖息地阻隔,江湖连通度降低,水文、泥沙、水温及水质等条件变化几方面分析了水利工程对鱼类栖息地的影响,提出了对河流进行综合治理的原则。2)采集了长江中下游的水质、底泥及鱼样,对其重金属含量进行了测试分析。结果表明,底泥中重金属含量是水体中的100-10 000倍,鱼体内重金属含量居于两者之间,底栖鱼类体内重金属含量相对中上层鱼类要高。鱼类食性与体内重金属含量也有密切的关系,底栖肉食性鱼类体内重金属含量最高,浮游植物食性鱼类体内重金属含量最低。3)建立了中华鲟栖息地适合度模型,模型由中华鲟栖息地适合度方程和二维水沙数学模型两部分组成。根据实测资料对模型进行了验证,结果表明,栖息地适合度方程形式正确,关键因子的选取和适合度曲线的取值合理;二维水沙模型针对弯道环流和横向输沙的改进,能更准确地模拟实际情况下的水流和泥沙输移情况。将模型运用来计算不同流量级下葛洲坝至宜昌河段中华鲟栖息地模拟发现,流量位于10000 m~3/s～30000 m~3/s时,中华鲟产卵场条件较为适宜,流量过大或过小均对产卵产生不利影响。4)建立了“四大家鱼”栖息地适合度方程,将其与一维数学模型结合建立了“四大家鱼”栖息地适合度模型。对1998年宜昌至城陵矶江段栖息地适合度的模拟发现,计算值与实测统计分布吻合较好。不同基准流量下,不同日流量涨幅的家鱼栖息地适合度模拟显示,日涨水幅度在800 m~3/s以上时,家鱼产卵场适合度较高。更多还原

【Abstract】 Dam construction on rivers and other human activities impact the environment and ecology while they provide flood safety, power generation, irrigation and water resources. This paper studies the environmental and ecological responses of the middle and lower Yangtze River stressed by dams, pollution and other human activities through field investigation, analysis, and numerical modeling. The main results are as follows:1) Fish community and fishery harvest are impacted by dam construction and habitats fragmentation. Statistical analysis shows that most fish species like habitats with low velocity. The river training and management should aim at reduce flow velocity.2) The concentration of heavy metals (Cr, Cd, Hg, Cu, Fe, Zn, Pb and As) in water, sediment, and fish/invertebrate were investigated in the middle and lower reaches of the Yangtze River during 2006-2007. The concentrations of heavy metals were 100-10,000 times higher in the sediment than in the water. Benthic invertebrates had relatively high concentrations of heavy metals in their tissues due to their proximity to contaminated sediments. The pollutants were accumulated in the food chain. Benthic invertivore fish had moderately high concentrations of heavy metals whereas phytoplanktivore fish, such as the silver carp, accumulated the lowest concentration of heavy metals.3) Analysing the life cycle and habitat conditions of Chinese sturgeon, habitat suitability equations are developed and suitability distribution curves are obtained. Twelve groups of survival rate of juvenile Chinese sturgeon under various conditions in 1982 to 1993 are used to test the equation. The calculate result agree well with these data. A two-dimensional sediment mathematical model is developed, which is coupled with a Chinese sturgeon habitat model. The model is used to simulate the Chinese sturgeon spawning sites in the reach from the Gezhouba dam to Yichang in 1999 and 2003. The results show that simulated result coincide with measured data. The model is used to calculate the habitat suitability index for different scenarios, the habitat suitability index value is high for the discharge falls within the range of 10000～30000 m~3/s for Chinese sturgeon to spawn, higher and lower discharges are not so suitable for the Chinese sturgeon to spawn.4) This paper also develops a one-dimension habitat suitability model for the four major Chinese carps. They are the black carp (Mylopharyngodon piceus), the grass carp (Ctenop haryngodon idellus), the silver carp (Hypoph thal michthys molitrix) and the big-head carp (Aristichyths nobilis), which are the major fishery species in the Yangtze River. The model is used to simulate the habitat suitability for the four carps in the reach from Yichang to Chenlingji. The simulated results agree with measured data. The modeling results indicate that the four carps will find the reach the best habitat for spawning if the daily-average discharge is in the range 8000～15000m~3/s with an increment of discharge higher than 800m~3/s per day.更多还原