子汇水区分割对SWMM低影响开发模拟的影响研究

低影响开发(LID)设施在我国海绵城市建设中被广泛使用,在规划和设计阶段利用雨水管理模型(SWMM)评价其效果是工程界普遍做法。SWMM可以采用两种方法实现LID设施的模拟,一是在子汇水区内添加一种或者多种LID设施,取代等量的子汇水区内非LID面积,二是用单一的LID设施占据全部的子汇水区。基于SWMM地表径流演算原理,通过分析单个子汇水区在不同情况下分割形成的子面积几何属性差异所造成的水文过程变化,发现前一种方法的子汇水区分割会影响到整体水文效应,进而干扰对LID设施效果的定量分析。后一种方法不存在子面积调整的问题,但也应确保LID添加前后模型网络结构不变,排除由于子汇水区调整可能带来的不利影响。

Influence of Subcatchment Partitioning on SWMM's Low Impact Development Simulation

Low impact development (LID) facilities are widely used in the sponge city construction of China. In the stage of planning and design, it is a common practice to use Storm Water Management Model ( SWMM) to evaluate the performance of LID facilities. There are two different approaches in SWMM to simulate the LID facilities within a subcatchment. One is to place one or more controls in an existing subcatchment in order to displace an equal amount of non-LID area from the subcatchment. The other is to create a new subcatchment devoted entirely for just a single LID practice. Based on the principle of surface runoff calculation of SWMM , the variation of hydrologic process which was caused by the difference of geometrical properties of subarea due to the division of a single subcatchment under different conditions was analyzed. It was found that the former approach ' s subcatchment partitioning would affect the overall hydrological effect and then interfere with the quantitative analysis of the performance of LID facilities. The latter approach did not have the problem of subarea adjustment, but it should also ensure that the structure of the model network was unchanged before and after the addition of LID controls, and avoid the potential adverse effects caused by the adjustment of subcatchment.