河南省降雨侵蚀力时空变异特征

Spatial and temporal variations of rainfall erosivity in Henan Province

利用河南省119个气象台站自建站始至2003年的逐日降雨量资料,计算其所代表县(市)的逐年与平均降雨侵蚀力,并利用GIS等工具分析河南省降雨侵蚀力的时空变异特征。结果表明:河南省多年年均降雨侵蚀力总体趋势是由北向南递增,最大值出现在南部的新县、鸡公山、商城与桐柏、平舆,其值均超过7 000 MJ.mm/(hm2.h.a);河南省多年年均降雨侵蚀力排序结果可分为5个区域等级,基本与等值线一致;河南省各地的降雨侵蚀力在不同年份变异较大,FFT(快速傅立叶变换)表明无明显的年际周期性规律;河南省降雨侵蚀力的年内变化趋势表现为单峰型,侵蚀主要发生在7—9月份,集中度在北部区域均超过60%;河南省降雨侵蚀力与年侵蚀性降雨量或年侵蚀性降雨量和逐日侵蚀性降雨量之间存在极显著的线性相关性,相关系数分别为0.967 2和0.994 2。

Rainfall is the main factor that causes soil erosion,and rainfall erosivity is the main dynamic index.So,accurately estimating the rainfall erosivity and analyzing its spatial and temporal variation is the key to predict soil erosion.Using the daily rainfall data of 119 meteorological sites in Henan Province from the year the site establishing to the year 2003,this paper calculated the rainfall erosivity of 119 sites in Henan Province,and analyzed its spatial and temporal variation.The results showed that： the yearly average rainfall erosivity in Henan Province generally increases from north to south,and the maximum value appears in Xinxian County,Jigongshan Mountain,Shangcheng County,Tongbai County and Pingyu County in the southern part of Henan Province,where erosivity are all above 7 000 MJ·mm/（hm2·h·a）.According to yearly average rainfall erosivity,Henan Province can be classified 5 regional zones,which are consistent with rainfall erosivity isoline.The rainfall erosivity of all sites varies significantly with different years and has no yearly periodical principle by fast fourier transform（FFT）.In one year period,the erosivity shows a mono-peak type,and mainly occurs in July to September with the concentration rate of 60% in the northern part.The erosivity has significant relationship with yearly erosion precipitation or the yearly erosion precipitation and daily erosion precipitation,and the correlation coefficient are 0.967 2 and 0.994 2,respectively.