基于“9·7”特大暴雨的深圳河流域防洪能力分析

Flood Control Capacity of Shenzhen River Basin during"9·7"Torrential Rainfall

为探究深圳河流域当前防洪能力能否满足设计标准,基于一维水动力数学模型,对深圳河流域2023年“9·7”特大暴雨的洪水过程进行模拟,并进一步模拟分析不同地形及不同糙率下的流域防洪能力,模拟结果表明,2016—2020年的清淤工程后,深圳河干流的防洪能力已由部分河段不足20年一遇提升到整体满足50年一遇。但由于清淤后河床快速回淤抬高和河道内植被生长导致糙率增加,支流莲塘河上游河段不能满足50年一遇的防洪标准。目前深圳河的防洪面临扇形集雨地貌叠加城市化发展、河道清淤后回淤明显以及河口红树林不断扩张等不利下垫面条件、极端灾害天气频发和内涝风险严重等挑战,需要从流域层面对防洪能力的提升进行总体方案布局,采取蓄、滞、分、泄、挡等各项措施相结合的方法,进一步削减洪峰流量和增加河道行洪能力。

To evaluate whether the current flood control capacity of the Shenzhen River Basin meets design standards,a onedimensional hydrodynamic mathematical model was employed to simulate the flood process during"9·7"torrential rainfall.Additionally,simulations were conducted to analyze the flood control capacity of the basin under different topographies and roughness conditions.The simulation results indicate that the dredging projects carried out between 2016 and 2020 have enhanced the flood control capacity of the main stream of the Shenzhen River from less than a 20-year return period in some sections to a 50-year return period overall.However,rapid sedimentation and vegetation growth in the riverbed after dredging increase roughness,preventing the upstream section of the Liantang River tributary from meeting the 50-year flood control standard.Currently,the Shenzhen River faces unfavorable underlying conditions,including a fan-shaped catchment topography combined with urban development,significant sedimentation following dredging,and continuous expansion of mangroves at the river mouth,as well as challenges such as frequent extreme weather events and significant urban waterlogging risks.Therefore,to enhance flood control capacity,it is necessary to develop a comprehensive strategy from a basin-wide perspective.A combination of measures including storage,retention,diversion,discharge,and blocking can be used to further reduce peak flood discharges and increase river flood conveyance capacity.