川北典型小流域产流对降雨的多时间尺度响应规律

为了解川北深丘区典型小流域河川径流动态变化规律,以嘉陵江李子口小流域为研究对象,基于2005～2016年的降雨、径流等实测数据,采用相关分析、降雨弹性系数、流量历时曲线等方法探讨了径流对降雨的响应规律。结果表明:(1)径流深和降雨量年际差异性均较大,整体呈不明显上升趋势,径流深的上升幅度略小于降雨量;(2)降雨量和径流深年内分布极不均匀,6～9月分别占年值的67.4%和78.5%,夏季易产生洪涝灾害;(3)极丰水流量、平水流量和极枯水流量分别为2.9、0.2、0.01 m~3/s。极丰水事件通常由长历时暴雨导致;极枯水日则多因长期无降雨或仅少量降雨;(4)典型次降雨中,暴雨、大雨、中雨的流量过程线从尖瘦型转变为平坦型,流量峰值滞后时间依次为1.5、3.67、5 h,滞后时间随着次降雨量的减小而变长,流量过程线的增长幅度随着次降雨量减小而变小。综上,径流和降雨在各时间尺度上均呈极显著相关(P0.01),不同时间尺度响应规律表现出较大的差异性。

Response of Runoff to Rainfall in Multi-time Scale of Typical Small Watershed in Northern Sichuan Province

Abstract：In order to understand surface runoff in deep hilly region of northern of Sichuan province, Lizikou catchment acted as the research area in Jialing River watershed. Based on the observed rainfall and runoff data from 2005 to 2016, correlation analysis, elastic coefficient of precipitation and flow duration curve applied to reveal the change regularity and correlation between rainfall and runoff. The results were as followed: (1) Annual precipitation and runoff was uneven distribution under inter-annual scale. The increase tendency of precipitation and runoff was not significant. The increase tendency of runoff is less than that of rainfall. (2) The monthly distribution of rainfall and runoff is extremely uneven. From June to September, the rainfall and runoff depth accounted for 67.4% and 78.5% of that in whole year, respectively. As a result, it prone to flooding in summer. (3) Extremely high flows, normal flows and extremely low flows were 2.9, 0.2 and 0.01 m ³/s, respectively. Extremely high flows caused by prolonged rainstorm. Normal flows often emerged during no rainfall in the wet year or during the heavy rain and rainstorm in the dry year. Extremely low flows were mostly due to no rainfall or only a small amount of rainfall. (4) In the typical individual rainfall, the flow during curve under heavy rain, moderate rain and light rain transferred from sharp-thin to flat. The lag times for peak flow ware 1.5 h, 3.67 h and 5 h for light rain, moderate rain and heavy rain, respectively, which became longer with the decrease of rainfall. Peak flow became lower with the decrease of rainfall. All in all, the correlation between rainfall and runoff is extremely significant in yearly, monthly, and daily (P<0.01). There are great differences among different time scales.