A Flood-Attenuating Impervious Surface Layout Planning Framework: Integrated Storm Water Management Model with Harmony Search

The increased impervious surface in an urban system is considered to have significant impacts on hydrological processes, while the impact of the imperviousness spatial distribution on the regional rainstorm flood process is yet to be comprehended. We propose a spatial allocation optimization system coupled with a harmony search algorithm (HS) and storm water management model (SWMM) to search the optimal imperviousness layout. The new optimization system was applied in an experimental site with an area of 0.5 km2. The distribution characteristics of the model-projected optimized imperviousness layout were analyzed. The main findings are as follows: (1) the flood peak in the outlet section can be effectively reduced by 4.01% to 35.62% merely through a reasonable optimized layout, without changing the scale of construction land; (2) in the optimized imperviousness layout scheme set, the pattern where the imperviousness is concentrated at both ends of the catchments is dominant for lighter rainfalls, while the pattern where the imperviousness is centered in the middle reaches is dominant for heavier rainfalls; and (3) in small rainfall events, with the increase of the average flow distance of the imperviousness, the flood peak tends to decrease first and then increase; in intensive rainfall events, it is almost the opposite. The findings can provide scientific guidance for flood control design in new town planning and old city reconstruction.