Urban Flood Hazard Modeling and Mapping Using PCSWMM

Abstract

"Urban flood" during monsoon becomes an unavoidable experience due to land use changes along with uneven rainfall distribution and the existing drainage system often fails to dispose stagnant water. In this connection, personal computer stormwater management model (PCSWMM) 2D software was adopted as a predictive tool to estimate flood depth for Chittagong, Bangladesh. Firstly, the non-parametric Mann-Kendall trend test was used to analyse rainfall amount and extreme events during 1949–2016. Secondly, magnitudes of the changes in rainfall events were acquired. Thirdly, daily as well as consecutive days' annual maximum rainfall data in the different return periods were estimated by Weibull's and Gumble's methods to develop a rainfall intensity-duration-frequency curve. Finally, PCSWMM simulated flood depths were used to prepare the flood hazard map using ArcGIS10.1. Based on the inundation depths, inundated areas were classified into eight qualitative hazard classes. Therefore, it is envisaged that the applied approach could be a useful means.