南小河沟流域降水特性及趋势分析

Analysis of rainfall characteristics and it's tendecy in Nanxiaohegou Basin

应用降水倾向率法和M ann—kendall检验法等方法对南小河沟流域1989～2004年雨量和雨日分布特征及其变化规律进行了分析。结果表明：降水主要集中在5～10月份,其中夏季降水量占全年降水量50.2%,年平均降水日数为89 d,其中降水量大于等于1.0 mm的降水日数占全年的66.9%,大于等于10.0 mm的降水日数全部集中在3～11月份,大于等于25 mm、50 mm主要集中在5～10月份。相对于年平均降水量520 mm而言,本地区正常降水年份占38%,异常降水占62%。90%的最长干旱持续期出现在冬季,但春末夏初也会出现10～20天的干旱天气。从年际变化看,流域年降雨量、汛期雨量均呈增加的趋势,旱期雨量呈减少的趋势。

This paper analyzed the annual precipitation, rainy days distribution characteristics and variation during 1989-2004 of Nanxiaohegou Basin, by using the precipitation tendency rate method and the Man-kendall inspection method. The results indicated that most of the precipitation occurred in May to Oct. , among them the precipitation occurring in summer accounted 50. 2 % for the whole yearly rainfall, the yearly average raining days was 89 days,also the precipitation more than 1.0 mm perday was accounted 66.9 % of the yearly raining days, and the pre- cipitation more than 10. 0 mm perday was completely concentrated in May to Nov. , while more than 25 mm or 50 mm per day was mainly concentrated in May to Oct. Compared with the annual precipitation （520 ram）, normal precipitation years were accounted for 38%, the unusual precipitation years accounted for 62 %. 90 % of the longest drought period will be appeared in winter, but in 10 to 20 days drought might be appeared in late spring and early summer. Regarding to the yearly change, the annual precipitation and rain fall in flood season were assumed an increasing tendency in this basin, while the precipitation in drought period was decreased gradually.