下荆江河道演变对天鹅洲自然保护区的影响及对策研究

Effect of Lower-Jingjiang River Evolution on Tianezhou Natural Protect Area and Countermeasures

介绍了石首下荆江故道天鹅洲2个国家级自然保护区简况;论述了下荆江典型蜿蜒性河道的特性,因复杂的江湖关系,使该河段河道演变更为复杂。20世纪50年代后实施了一系列河势控制、护岸工程,制约了河道横向摆动,但目前石首一带仍处于剧烈变化中;一维数学模型计算成果表明,三峡枢纽运行后下荆江特别是保护区所处的石首至监利河段的冲刷量、冲刷深度及水位下降,均居长江中下游河段之冠,河道可能会发生剧烈演变;分析了三峡运行后下荆江河道演变对故道保护区的影响,即清水下泄冲刷使河道甚不稳定而影响保护区安全以及水位降低减少故道水体交换几率等不利影响。提出了加强研究、观察,采用工程措施增加故道水体交换以及严禁有毒污水排入故道等对策措施。

This paper introduces brief status on two natural protection areas on the former river of Lower-Jingjiang, and represents the river characteristics of Lower-Jingjiang, which is a typical meandering river and has complicated connecting retation with Dongting Lake, and the complexity of its river evolution. Since 1950s, a series of river control and bank protection works have been implimented, so the swing of river is restricted, but now the river reach near Shihou is still in acute change. According the calculated results of 1-D mathematical model, after Three Gorges Project （TGP） running, the scouring quantity, scouring depth and water level degradation of the Lowerdingjiang reach, especially Shishou to Jianli reach, would be maximum among the downstream streches of the dam, so this reach will occur acute evolution. The paper analyses the influences of Lower -Jingjiang evolution on Tainezhou natural protection area after TGP running and unfavorable aspects including both affecting the safety of natural protection area due to reservior clear-water releasing and decreasing the water -body exchange with the former stream because of water level degradation. The countermeasures are put forward, including intensifying research and observation, adopting engineering measure to increase water-body exchange and strictly prohibiting proisonous sewage to be drained in.