不同降雨强度下LID改造对径流量的削减效果

以重庆市海绵城市建设试点区域秀山县为研究对象,通过实时监测传统片区和低影响开发(LID)片区的降雨径流数据,探析LID片区在不同降雨强度下对径流量的削减效果。结果表明,经LID改造后,地面透水性增大,所容纳的雨水量增加,与传统开发模式相比,中雨条件下对径流总量和峰值的削减率分别可达到80. 4%和56. 0%;LID措施的蓄水容积有限,不同降雨条件下对径流总量和峰值的削减程度不同,削减程度排序为:中雨(80. 4%、56. 0%)>大雨(69. 4%、64. 4%)>暴雨(56. 1%、60. 8%),而且随着降雨等级的增大,LID片区的径流产生时间和峰现时间的滞后效果减弱,在暴雨条件下与传统片区无明显差别;LID片区是否产生径流以及产生多大的径流,主要由降雨强度决定,而与降雨量关系不大,在本研究中,当降雨强度> 0. 2 mm/min时才会产生径流,且降雨强度越大,径流量就越大。

Runoff Reduction Effect of Low Impact Development(LID)Reconstruction under Different Rainfall Intensities

Through real-time monitoring rainfall runoff data in traditional development area and low impact development(LID)area in Xiushan County,a pilot area of sponge city construction in Chongqing City,the runoff reduction effect of LID area was analyzed under different rainfall intensities.After LID construction,the permeability and rainwater retention capacity of underlying surface increased.Compared with the traditional development mode,the reduction rates of total runoff and peak runoff were 80.4%and 56.0%respectively under the condition of moderate rain.The rainfall storage capacity of LID facilities was limited,and the reduction effect of the total runoff and peak runoff under different rainfall conditions was different.The runoff reduction effect from high to low was:moderate rain(80.4%and 56.0%),heavy rain(69.4%and 64.4%),and rainstorm(56.1%and 60.8%).With the increase of rainfall intensity,the lag effect of runoff generation time and peak occurrence time in the LID area weakened,and there was no significant difference between the LID area and traditional development area under the condition of rainstorm.Whether and how much runoff was generated in LID area was mainly determined by rainfall intensity,but it had little to do with rainfall volume.When the rainfall intensity was higher than 0.2 mm/min,there would be runoff.In addition,the higher the rainfall intensity,the more the runoff.