湖北丹江口水库库区降雨侵蚀力特征

降雨侵蚀力(R)指数是估算土壤侵蚀量的一个基本因子，但如何利用气象站常规降雨统计资料估算R值具有重要的实践意义。利用湖北丹江口水库库区4个观测站(丹江口、十堰、郧县、郧西)的多年逐日降雨资料，通过比较分析多个经验模型对该地区的降雨侵蚀力的计算结果，优选出了表现最佳的估算模型，并用其计算结果分析了库区年降雨侵蚀力的空间分布和时间变化特征。结果表明，湖北丹江口库区丹江、郧西、十堰、郧县的年均降雨侵蚀力分别为3 331.94、3 272.40、3 501.21、3 187.94 MJ·mm/hm²·h·a，4个测站的均值为3 323.37 MJ·mm/hm2·h·a，空间分布比较均匀，与多年平均降雨量分布类似；降雨侵蚀力主要集中于5～9月份，占全年的88.60%以上；库区4个测站年降雨侵蚀力值波动较大，以郧西和十堰为甚，其最大单次降雨侵蚀力分别占其研究时段内总降雨侵蚀力的6.94%和4.87%。离差系数Cv(0.45～0.58)和趋势系数r(绝对值0.05～0.08)计算结果表明研究年限内年均降雨侵蚀力整体趋势保持平稳。

RAINFALL EROSIVITY IN THE DANJIANGKOU RESERVOIR REGION,HUBEI PROVINCE

Rainfall erosivity is an important factor for soil loss estimation,yet how to estimate rainfall erosivity in regions with limited rainfall information is critical for water and soil conservation.In this study,several empirical models were used to estimate rainfall erosivity based on daily rainfall data from 4 meteorological stations in the Danjiangkou Reservoir region,i.e.Danjiangkou，Shiyan，Yunxi and Yunxian of Hubei Province.By comparing the estimated results with existing research results,one of the best performed models was selected for regional rainfall erosivity computation.The average rainfall erosivity is 3 331.94,3 272.40,3 501.21,3 187.94 MJ·mm/hm²·h·a for Danjiangkou,Yunxi,Shiyan and Yunxian,respectively.The estimated rainfall erosivity shows homogeneous distribution cross the reservoir region.The rainfall erosivity concentrates in May to September,comprising more than 8860% of its annual value.The single rainfall erosivity has large variability,especially for Yunxi and Shiyan where the maximal single rainfall erosivity accounts for 6.94% and 4.87% of the total rainfall erosivity respectively.The coefficient of change trend r(ranging from 0.45 to 0.58)and the coefficient of variation Cv(ranging from 005 to 008)indicate that the rainfall erosivity has been relatively stable in the past half a century in the reservoir region.