渠江流域汛期强降水时空分布特征

本文从分析研究渠江流域汛期强降水时空分布入手,试图揭示该流域21世纪以来洪水频发的原因。经对渠江流域1970~2012年降水资料分析研究得出:(1)渠江流域汛期降水量、暴雨日数、降水变差系数呈“北大南小”的空间分布;“北区(河流汇水区,下同)”近年来汛期降水量增大、暴雨频率增加、降水趋于极端;(2)短时强降水多发生在04~08时,频发区主要位于“北区”,近年来频次呈上升趋势;(3)小时雨强极值“北区”普遍大于“南区”;近43年渠江流域汛期小时雨强极值总体呈增大趋势,“北区”尤为明显。因此,渠江流域汛期发生的强降水趋势性变化,是导致该流域洪水频发的主要原因之一。 

Spatial-temporal Distribution Characteristics of Flood Season Precipitation over the Qujiang Basin

In this study, Qujiang river basin in Sichuan was chosen as the research area to reveal the main reasons which lead to the high frequency floods since the 21st century. The spatial -temporal distribution and short -period heavy precipitation characteristics were analyzed by using the hourly precipitation data of 1970 -2012. The results indicate that ： 1 ）The distribution of precipitation, rainstorm days and coefficient of variation in northen area turns out to be larger than it in southern area in Qujiang basin ; increasing extremely trends of precipitation had been found in northern area in recent years. 2） The short - period heavy precipitation occured in northern area a lot and increased recent -8am 3 ）During the latest 43 years, the maximum hourly rainfall intensity years. It is also find that it usually happens during 4 of most area in Qujiang basin has increased, especial- ly in northern area where hourly rainfall intensity is always greater than it in southern area. Therefore, the changing trends of heavy precipitation over Qujiang basin is one of the essential reasons which causes floods frequently in this area.