非连续降雨条件下径流控制效果数值模拟研究

Numerical simulation of runoff control under discontinuous rainfall

为研究低影响开发设施径流控制效果对降雨时间间隔的响应规律,以西咸新区沣西新城天福和园LID小区为例,构建了SWMM计算模型。以不同时间间隔的两场独立的设计降雨作为非连续降雨事件,研究其径流控制的影响因素。研究结果表明随着降雨间隔从2h增至48h,非连续降雨径流控制率从81.46%增加到84.23%,且降雨事件中后场降雨有滞峰及峰值削减效果;随着降雨强度的增加,非连续降雨的径流控制率在降低。重现期为1年比重现期5年的非连续降雨的径流控制率高约为14%左右,且在降雨总量一样的情况下,降雨的时间分配也会影响径流控制效果,先小雨后大雨比先大雨后小雨的降雨过程的径流控制率高4%左右;重现期一定时,随着降雨历时从1h增加到2h、5h,非连续降雨的径流控制率分别降低1.2%、2.6%。

In order to study the response rule of runoff control effect of low-impact development facilities to rainfall interval,the SWMM calculation model of the study area was constructed by taking of Tianfuheyuan,Fengxi new city,Xixian new district as an example.Two independent design rainfall at different time intervals were considered as a discontinuous rainfall event,and the factors affecting runoff control were studied.The results show that with the increase of rainfall interval from 2 hto 48 h,the runoff control rate of discontinuous rainfall increased from 81.46%to84.23%.With the increase of rainfall intensity,the runoff control rate of discontinuous rainfall decreased.The runoff control rate of the discontinuous rainfall in the recurrence period of 1 year is about 14%higher than that of 5 years,and in the case of the same amount of rainfall,the time distribution of rainfall will also affect the runoff control effect.The runoff control rate of the first small and then large rainfall process is about 4%higher than that of the first large and then small rainfall process.At a certain recurrence period,with the increase of rainfall duration from 1 hto 2 hand 5 h,the runoff control rate of discontinuous rainfall decreased by 1.2%and 2.6%respectively.