向家坝蓄水前后长江上游珍稀特有鱼类国家级自然保护区物理完整性评价

Assessment of Physical Integrity of National Nature Reserve for Rare and Endemic Fishes in Upstream Yangtze River Before and After Xiangjiaba Dam Impoundment

采用流量过程变异程度、高流量频率、高流量历时偏差、岸坡稳定性、栖息地类型多样性、底质类型多样性、河岸植被覆盖度、垂向透水性等8项指标对向家坝蓄水前后长江上游珍稀特有鱼类国家级自然保护区部分关键河段的物理完整性进行了评价研究。结果表明:赤水河的物理完整性远高于长江干流,长江干流的3个河段中江津段的物理完整性较高,其次是宜宾和合江;向家坝蓄水前后,高流量频率、高流量历时偏差、栖息地类型多样性、垂向透水性等4项指标差异较大;向家坝蓄水对保护区关键河段水文过程,特别是脉冲流量及其持续时间、底质中值粒径和水深、流速的分布等具有一定程度的影响。研究结果可为长江上游干支流物理完整性评价提供借鉴。

The physical integrity of key reaches of the National Nature Reserve for rare and endemic fishes in the upstream of Yangtze River is assessed in consideration of eight indicators,inclusive of flow process variability,high flow frequency,high flow duration deviation,bank slope stability,habitat type diversity,sediment type diversity,riparian vegetation coverage and vertical permeability. Results show that the physical integrity of the Chishui River is much higher than that of the mainstream Yangtze River. And among the three reaches of mainstream Yangtze River,Jiangjin reach has high physical integrity,followed by Yibin reach and Hejiang reach. Moreover,four indicators（ high flow frequency,high flow duration deviation,habitat type diversity,vertical permeability） vary greatly before and after the impoundment of Xiangjiaba dam which affects the hydrological process of the key reaches,especially the indicators of pulse flow and its duration,median diameter in sediment,and distribution of water depth and velocity.