高度城市化区域汇水域尺度LUCC的降雨径流调蓄效应--以上海城市绿地系统为例

Rainfall-runoff storage-infiltration effect of LUCC in highly urbanized region on a catchment's scale:Shanghai urban green space system as an example

快速城市化进程导致的土地利用/土地覆被变化(LUCC),对城市地表水文过程影响显著。城市绿地作为主要的城市透水型下垫面类型,具有良好的降雨径流调蓄效应。利用2000、2003年上海中心城区小尺度城市汇水域的LUCC、降雨和径流资料,以绿地系统为例,分析了高度城市化区域内,面积分别为2.60km2和2.77km2的相邻汇水域LUCC的水文过程。结果表明,高度城市化区域内小尺度城市汇水域的城市绿地系统具有良好的削减城市雨水径流总量和延缓雨水径流洪峰现时的调蓄效应。案例研究显示,在绿地系统面积比例分别为39.13%和27.36%,边界条件相近的对比城市汇水域内,10%绿地系统面积比例差,及其绿地结构、覆被植物和土壤类型的差异共同造成:①对比汇水域年径流系数存在约0.3的差别;②对24h降雨量为42.8mm的大雨径流过程,延后径流峰值出现时间约20min;③对24h降雨量超过270mm的特大暴雨径流过程,削减地表径流系数约0.1。

Land use and cover change（LUCC）caused by rapid urbanization had remarkable influence on urban surface hydrological processes.The urban green space as one main penetrative underlying surface type,presents a strong storage-infiltration effect.According to LUCC,rainfall and runoff data collected from highly urbanized area in central Shanghai in 2000 and 2003,the hydrological processes of LUCC with areas of 2.60km2 and 2.77km2 adjacent catchments,respectively were analyzed.The results exhibited the green system,in a highly urbanized region on a small catchment＇s scale,had obvious storage-infiltration effects to eliminate total amount of rainfall-runoff,and to extend time-lag of runoff flood peak Case study of two urban catchments with a similar boundary condition,39.13% and 27.36% area of green spaces respectively,showed that 10% area difference between green systems,and the differences among green structure,cover plants and soil types could cause（i）0.3 difference for annual runoff coefficient between two catchments,（ii）20min extension for runoff peak in the process of 42.8mm precipitation within 24h,（iii）0.1 runoff coefficient elimination beyond 270mm storm runoff process within 24h.