洞庭湖流域极端降水指数变化特征分析

Variation Characteristics Analysis of Extreme Precipitation Indexes in Dongtinghu Lake Basin

基于洞庭湖流域17个气象站1961～2009年逐日降水资料,采用Mann-Kendall检验法和滑动t检验法对洞庭湖流域四种极端降水指数进行趋势分析和突变检验。结果表明,四种极端降水指数在洞庭湖流域不同测站表现出不同的变化趋势,但变化均不显著,基本上未通过置信水平检验,非常湿天、极端湿天在西北和东南方向的各测站均表现为上升趋势,雨日数在位于北部的部分测站表现为上升趋势,日最大降水量在大部分测站均表现为上升趋势;各指数突变年主要集中于20世纪后期,2001年后明显减少,表现突变减少年的测站数量明显多于表现突变增加年的测站数量。

Based on the daily precipitation data of 17 hydrological stations during 1961-2009, four extreme precipitati- on indices in the Dongtinghu Lake basin are used to investigate the variability and tendency of extreme rainfall with Mann- Kendall test technique and moving t test. The results show that the trends of extreme precipitation indices are largely different; the trends are not significant and it do not pass the confidence level test; extraordinary wet weather and extreme wet weather in northwest and southeast stations appear the ascending trend; the numbers of rainy day in north stations appear the ascending trend; the daily maximum precipitation in most stations appear the ascending trend; the sudden change of index year mainly concentrate on the late of of stations of sudden decreased year is obviously more the 20th century and it obviously decreases after 2001 ; the number than that of sudden increased year.