漫湾电站库区降雨侵蚀力时空变化

漫湾水电站是澜沧江水能梯级开发的第一个干流大型水电站，加强库区水土流失治理与监督监测尤为必要，而降雨侵蚀力的时空分布规律研究则是实现区域土壤侵蚀定量监测预报的重要基础。根据有关降雨侵蚀力的计算方法，利用漫湾电站库区4个测站1980～2000年的逐月平均降雨资料，估算了其降雨侵蚀力R值的时空分布规律及其变化特征。结果表明：漫湾电站库区多年平均降雨侵蚀力在1 9336～3 9727 MJ·mm/hm2·h；R值的年内变化显著，且较大值集中分布在雨季的5月～10月，平均R值占全年的867%，尤其6～8月连续3个月的降雨侵蚀力平均占全年侵蚀力的一半以上；R值的年际变化显示20世纪90年代漫湾电站库区降雨侵蚀力比80年代平均增加2835 MJ·mm/hm2·h；R值的空间分布上以凤庆站点的年降雨侵蚀力最大；南涧站点的年降雨侵蚀力最小，但是其年际波动幅度较大。全面地分析了漫湾电站库区降雨侵蚀力R值的时空变化特征，为该地区有效防止与监测水土流失情况、更好地安置水电站工程移民提供参考。

SPATIAL TEMPORAL DISTRIBUTION OF RAINFALL EROSIVITY INTHE STORAGE AREAS OF MANWAN HYDROPOWER STATION

Rainfall erosivity is a fundamental factor for quantitative monitoring and assessment of soil erosion.Analysis of the spatial temporal characteristics of R value in the storage areas of Manwan Hydropower Station may supply good advices to prevent soil erosion effectively in local region.The paper studied on rainfall erosivity (R value) and its spatial temporal distributions in the storage areas of Manwan Hydropower Station,based on the continuous rainfall data from 1980 to 2000 at four weather stations.The results indicate that the highest R value in this region is 3 9727 MJ·mm/hm2·h,while the lowest is 1 9336 MJ·mm/hm2·h.In general,the seasonal distribution of precipitation is analogical with that of rainfall erosivity on concentration extent.The rainfall erosivity is mainly distributed in the period from May to October in all stations and the rainfall erosivity of continuous three months (June~August) accounts for over half of that in a year on average.Annual rainfall erosivity in all stations fluctuates periodically,and the annual change of rainfall erosivity shows the positive trends in most parts since 1980's.The rainfall erosivity tends to increase by 2835 MJ·mm/hm2·h from 1980 to 2000.There are a lot of differences between the annual changes of rainfall and rainfall erosivity.The spatial distributions of the annual rainfall show that R value is the highest in Fengqing,and it is the lowest in Nanjian.