19612019年大渡河流域降水集中度、集中期特征及径流响应研究

Characteristics of Precipitation Concentration Degree,Precipitation Concentration Period and Runoff Response in the Dadu River Basin During 19612019

基于大渡河流域19612019年逐日降水资料及19612010年大渡河出口铜街子河段径流资料,计算流域内降水集中期、集中度和径流系数,运用经验正交函数(EOF)、交叉小波变换等方法分析了集中期、集中度与径流的时空变化特征及相关关系。结果表明:(1)大渡河流域19612019年年均降水集中期和集中度的空间分布总体呈现上游向下游递增的变化趋势。(2)降水集中度在19761990年有明显增多趋势,1990年后增多趋势减缓;下游区域降水集中度标准差数值高,降水集中期在1990年以前存在显著的“上游早下游晚”的时间差异,但1990年以后时间差异逐渐缩小。(3)19612010年大渡河年径流系数呈弱递增趋势,降水集中期、集中度与径流量均有较好的时滞关系。

Based on the 19612019 precipitation data from the weather stations in Dadu River basin and the runoff data of Tongjiezi reach at the outlet of Dadu River during 19612010,the precipitation-concentration period(PCP),precipitation-concentration degree(PCD)and runoff coefficient are calculated,and their spatial-temporal variations are further studied by using the empirical orthogonal function(EOF),cross wavelet transform methods.It is found that:(1)from 1961 to 2019,the spatial distributions of PCD and PCP in the Dadu River basin showed an overall trend of increasing from upstream to downstream.(2)The PCD showed a clear increasing trend from 1976 to 1990,but slowed down after 1990.The standard deviation value of PCD was high in downstream region.There was a significant time difference in PCP before the 1990,but after the 1990,the time difference was gradually shrinking.(3)The annual runoff coefficient of Dadu River showed a weakly increasing trend during 19612010.In a word,there exists a good time delay relationship among PCP,PCD and runoff volume.