2009年7月珠江流域暴雨致洪成因分析

The Analysis of Precipitation and Flooding Cause of Formation in the Zhujiang Basin at the Beginning of July in 2009

利用常规和非常规气象、水文资料以及T639模式同化资料,对2009年7月初发生在珠江流域的暴雨致洪过程进行雨情和水情特征分析。结果表明,该次流域性洪涝是在有利的大尺度环流背景下,由南下冷空气和东移南支槽造成的两次暴雨过程产生的,具备华南汛期暴雨的典型特征。致洪暴雨导致多个水文站点水位起涨快、涨率大,洪峰流量高,属历史罕见。同时,雨带的移向与洪峰演进方向一致,干支流洪水遭遇,造成洪峰叠加,因而形成了珠江流域性大洪水。

The generally observed precipitation data and hydrological information and T639 data are employed to analyze the precipitation and flooding features which happened in the Zhujiang Basin at the beginning of July in 2009. The results show that the flood was caused by the twice heavy rainfall made by the southward cold air and the eastward south trough under the advantageous large scale circulation which had the typical features of the heavy rainfall in the pre-flood period in South China. The heavy rainfall caused the water level to rise rapidly, high-up rate, high discharge peak at many hydrological stations, which is rarely seen in history, at the same time, the movements of rain belts were in the same direction as the flood peak evolution, the flood of the main stream and the anabranch were encountered, which resulted in superimposed peaks, thus causing the valley a heavy flood.