淮河上游大坡岭流域土地利用方式变化引起的流域滞时变化

Response of basin lag time to land use change in Dapoling Basin in upper Huaihe River

以淮河上游大坡岭子流域(简称大坡岭流域)为研究区域,基于研究区域1965—2009年间的26场单峰洪水,计算流域平均滞时。以1985年为界,比较土地利用变化前后流域平均滞时的变化,并计算不同降雨量级的流域平均滞时,分析滞时与径流深和洪峰流量的相关关系。结果表明:土地利用变化引起的流域平均滞时变化很大;除了降雨形心到洪峰流量的时间TLPC在土地利用变化之后减少外(从9.98 h减少为5.26 h),另外3种滞时,降雨形心到流量过程线形心的时间TLC、降雨开始到洪峰流量的时间TLP和最大降雨强度到洪峰流量的时间TLPP均增大(分别从21.32 h、34.64 h、10.00 h增加到26.77 h、35.08 h、11.50 h)。大坡岭流域土地利用变化前后以及整个时期4种滞时和降雨量级存在一定联系,与径流深及洪峰流量无相关关系。

Based on 26 single-peak floods between 1965 and 2009 in the Dapoling sub-watershed（ or Dapoling Basin） in the upper Huaihe River,the mean basin lag time was calculated. The observed data were delimited by the year 1985 according to the land use change to compare the variation of mean basin lag time,calculate the lag time for different rainfall depths,and analyze the respective relationship of lag time with runoff depth and peak discharge. The results show that the land use change caused a large variation of the mean basin lag time. The lag time from the centroid of the rainfall hydrograph to peak time TLPCdecreased from 9. 98 h to 5. 26 h after the land use change. The lag time from the centroid of the rainfall hydrograph to the centroid of the discharge hydrograph TLC,the lag time from the beginning of a rainfall event to peak time TLP,and the lag time from the peak rainfall intensity to peak discharge TLPPincreased after the land use change. The TLC,TLP,and TLPPvalues increased from 21. 32 h to26. 77 h,from 34. 64 h to 35. 08 h,and from 10. 00 h to 11. 50 h,respectively. During the periods before and after land use change and the entire period in the Dapoling Basin,there was a certain relationship between the four lag time variables and the rainfall depth,but no relationship was found between lag time and runoff depth or between lag time and peak discharge.