试验研究三峡库区大宁河流域降雨侵蚀力的时空变化

目的]分析流域降雨侵蚀力时空变化规律，为水土流失预报及水土保持措施科学配置提供依据。方法]以三峡库区大宁河流域内13个雨量站41 a 日降雨资料为基础，采用侵蚀力简易模型，分析了该流域降雨侵蚀力的年内分配和年际变化规律，并在软件 ArcGIS 10．2支持下，探讨流域降雨侵蚀力时空变化特征。结果]大宁河流域年均降雨侵蚀力为7245．55 MJ ? mm／（hm2? h ? a），它在空间上与流域降雨分布特征基本一致，呈现由东、西向流域中部逐渐减小的趋势，而南北差异较小；最大和最小降雨侵蚀力分别位于流域西北部的建楼站和南部的巫山站；降雨侵蚀力多年变化范围为3619．55～11109．14 MJ ? mm／（hm2? h ? a）。降雨侵蚀力的年内分布呈双峰型，集中程度高，4—10月占全年的95％。结论]大宁河流域降雨侵蚀力和降雨变化年内分配一致，侵蚀力时空特征除与流域降雨量分布密切相关外，还与区域降雨格局及地形地貌等因素有关。

Temporal-spatial Variations of Rainfall Erosivity in Daning River Watershed of Three Gorges Reservoir Region

Objective] To analyze the spatio-temporal variation of rainfall erosivity in order to provide the basis for predicting soil erosion and evaluating the effectiveness of conservation measures.Methods] Based on the daily rainfall records(1970-2010) from 13 rain-gauge stations located in Daning river watershed in the Three Gorges reservoir region, the characteristics of annual and monthly rainfall erosivity were investigated. Meanwhile, by using GIS 10.2 software, spatio-temporal variation of rainfall erosivity was analyzed.Results] The annual rainfall erosivity(R-factor) was ranged from 3 619.55~11 109.14 MJ·mm/(hm²·h·a), and the mean value was 7 245.55 MJ·mm/(hm²·h·a). The spatial distribution of rainfall erosivity showed a decreasing trend from east and west to the central of the watershed, while there was no significant change from south to north. The distribution of rainfall showed a similar trend. The maximum and minimum rainfall erosivity occurred in Jianlou and Wushan station, respectively. The inner-annual distribution of the rainfall erosivity showed two peaks and highly concentrated in the period from April to October, which accounted for 95% of total annual rainfall erosivity.Conclusion] The spatio-temporal variation of rainfall erosivity is not only closely related to the distribution of rainfall amount, but also related to the regional rainfall pattern and local topography.