长江1870年特大洪水防御推演与对策研究

Study on flood control deduction and countermeasures in case of catastrophic flood in 1870 in Changjiang River Basin

1870年长江流域发生了特大洪水,枝城站洪峰流量重现期超1000 a一遇,造成极为严重的洪灾损失。为强化特大洪水风险防范,有效提升极端洪水灾害的应对能力,在分析1870年特大洪水雨水灾情特征、流域水文地理演变和防洪体系建设情况的基础上,对1870年特大洪水在现状防洪体系调度运用条件下的发生、发展、演进过程进行了推演模拟。结果表明:当前再遇1870年特大洪水,长江流域防洪体系可妥善应对并大幅减少洪灾损失,按调度规程发挥以三峡水库为主的水库群洪水拦蓄作用,并运用荆江分洪区等13处蓄滞洪区分洪、200多处洲滩民垸行洪后,长江防洪重点区域防洪安全总体可控,但洪水防御仍面临堤防长时间高水位运行存在安全隐患、蓄滞洪区与洲滩民垸行蓄洪运用困难、大量人员转移安置压力大等突出问题。根据1870年洪水推演成果,结合近年来长江流域防汛实践,从加强特大洪水风险机理研究、加快流域防洪工程体系建设、强化风险研判和优化调度、做好应急转移和救灾安置等方面提出了提升特大洪水防御能力的对策建议。

The 1870 flood in the Changjiang River Basin is an extraordinary and catastrophic event in the history,with peak flow returning period of over 1000 years at Zhicheng Station,causing extremely serious flood losses.In order to strengthen the ability to prevent catastrophic flood risk and effectively improve the ability to cope with extreme flood disasters,based on analyzing the characteristics of the catastrophic flood in 1870,the hydrological and geographical evolution of the Changjiang River Basin,and the construction of the flood control system,a retrospective simulation was conducted to deduce the occurrence,development,and evolution process of the catastrophic flood under the current flood control system.The results show that the current flood control system has ability to defend against the catastrophic flood in 1870 and can greatly reduce the flood losses.After dispatching the Three Gorges Reservoir and other reservoirs according to regulations,and applying 13 flood detention areas such as the Jingjiang flood diversion area and more than 200 polders,the flood control safety of the key areas in the Changjiang River Basin can be generally controllable.However,it still faces problems such as safety hazards of embankments,difficulties in the use of flood storage and detention areas,and high pressure on personnel relocation and resettlement.According to the results of retrospective flood simulation and the practice of flood control in recent years,the countermeasures and suggestions are put forward to improve the ability of mitigating catastrophic flood,including strengthening researches on mechanism of catastrophic floods,accelerating the construction of flood control engineering systems,enhancing risk assessment and optimizing scheduling,and improving emergency transfer and disaster relief resettlement.