降雨与植被变化对彭冲涧小流域径流影响的定量研究

A Quantitative Study of Impacts of Rainfall and Vegetation Changes on Runoff in Pengchongjian Small Watershed

降雨与植被变化对小流域径流影响的定量研究是当前研究的热点。运用Mann-Kendall检验法对彭冲涧小流域1983—2014年的降雨、径流序列进行突变分析,结果显示,2003年为降雨与径流的一致突变点。因此,以1983—2003年为基准期,2004—2014年变化期的年降雨量、年径流深分别减少8.7%、27.5%,年平均减少幅度分别为12.7和20.4 mm。相对于基准期,变化期春、夏季及年的径流深分别减少87.5、99.5和223.9 mm,其中降雨变化的贡献率分别为55.3%、80.5%和67.5%,植被变化的贡献率分别为44.7%、19.5%和32.5%。可以看出,在春季、夏季及年尺度上,降雨与植被变化对径流影响贡献率存在较大差异,总体上降雨变化的贡献率均大于植被变化的贡献率,尤其降雨充沛的夏季。

Quantitative study of impacts of rainfall and vegetation changes on runoff in small watershed has been a hotspot in current studies.In this study,Mann-Kendall rank test was used todetect the change point of annual rainfall and runoff in the period of 1983—2014,and a change point around 2003 was found.Compared to the baseline period of 1983—2003,the annual rainfall and depth of runoff decreased by 8.7% and 27.5%respectively,the annual mean amount was 12.7 mm and 20.4 mm respectively.The results of contribution rate of impact of rainfall and vegetation changes on runoff showed that,compared to the baseline period,the depth of runoff decreased by 87.5 mm,99.5 mm and 223.9 mm in Spring,in Summer and in every year respectively in the changing period,the rainfall changes had contribution rates of 55.3%,80.5% and 67.5% respectively,while the vegetation changes had contribution rates of 44.7%,19.5% and 32.5% respectively.The results show that,either in Spring,in Summer or annual scale,the contribution rates of rainfall changes and vegetation changes differ greatly.In general,the contribution rate of rainfall is greater than that of vegetation changes,especially in Summer with abundant in.