太湖流域平原河网降雨时程分布变化的洪水响应

Flood Response to Temporal Variation of Precipitation in Plain River Network Region in Taihu Lake Drainage Basin

近年来太湖流域平原河网地区洪涝灾害频发,居民的人身及财产安全受到了严重危害。降雨是导致本区域洪水的主要因素,其中最具代表性的降雨类型为梅雨和台风暴雨,由于二者时程分布特性有较大差异,其致洪机理也有所不同。以探究降雨时程分布对洪水过程的影响为目的,以太湖流域武澄锡虞水利分区为研究对象,采用MIKE 11与MIKE 21构建一、二维耦合水动力模型,利用实况洪水过程对模型进行率定验证,采用该模型对研究区域进行不同设计工况的模拟,讨论了次雨量、降雨历时以及降雨时程分布变化对太湖流域平原河网地区洪水过程的影响。结果表明:降雨时程分布对平原河网河道洪水过程有显著影响,其中长历时降雨对雨峰位置的后移较为敏感,短历时暴雨则受到降雨时间变差系数变化的影响较大,而次雨量变化则对二者都有显著影响。

Flood and waterlogging disasters in plain river network region in recent years have brought about severe damage to people’s lives and property safety.Rainfall is the key factor causing flood disasters in the region,of which the most typical ones are plum rain and typhoon rainstorm.The flood generating mechanism of plum rain and typhoon rainstorm varies because of different temporal distribution.In the aim of investigating the influence of rainfall’s temporal variation on flood process,a 1D-and 2D-coupled hydrodynamic model of Wuchengxiyu hydraulic district of Taihu Lake drainage basin was built with MIKE 11 and MIKE 21.The model was calibrated and validated by several measured flood events.Numerical simulation of flood processes under different design conditions in the study area was conducted.The influences of magnitude,duration and temporal variation of rainfall on flood process were examined.Results suggest that the temporal distribution of rainfall has apparent influence on flood in plain river network.Rainfall of long duration is sensitive to the delay of rainfall peak,while rainfall of short duration is largely affected by the time variance coefficient.Meanwhile,rainfall amount has evident impact on both long-duration and short-duration rainfall.