A methodology for simple 2-D inundation analysis in urban area using SWMM and GIS

Abstract

Urban waterlogging occurred frequently in recent years, causing serious social harms and huge economic losses. Accurate waterlogging warning is important for disaster prevention and mitigation. Urban rainstorm waterlogging processing based on Geographic Information System (GIS) and Storm Water Management Model (SWMM) can provide prediction and management of flood situation, but the previous methods of catchments from a single aspect of hydrology or geometry cannot reflect the dual impact of pipe networks and terrain to drainage, and the available inundation algorithms achieved some unreasonable results due to the artificial boundaries. In this paper, a methodology for simple 2-D inundation analysis in urban area using SWMM and GIS is introduced, which need not edit SWMM’s original code. Furthermore, a geometric method of catchments division and inundation algorithm are proposed to improve accuracy. The revised catchments division method provides a good result of supplementing the drainage of terrain, and the improved inundation algorithm can obtain a reasonable inundation distribution based on the principle of source diffusion and dynamic distribution without any boundary limit. The case study was performed in Longwen District of Zhangzhou, and good results are achieved: (1) The external outflow percentage of the revise method is always bigger than that of the geometric method, and the value of the revised method is 25.18%, while that of geometric method is only 19.56% at rainfall peak, and (2) the less the rainfall is, the less grids flooded in two algorithms there are with only 14.30% when the rainfall is 0.1 mm.