Impact of climate change on urban drainage systems in three selected coastal towns of bangladesh

As urban growth is increasing in coastal zones, urban drainage system would suffer from additional stresses due to water logging. Moreover, climate change is to enhance natural disasters like floods and heavy rainfall events. So, urban drainage and its performance will be important issues in the coastal towns of Bangladesh. In this study, storm water management model (SWMM) has been used to assess the future possible drainage conditions for three selected towns of coastal areas – Amtali, Galachipa and Pirojpur. Design storm of 2-hour 10 year return period and design water level of surrounding rivers of 20 year return period were considered for simulation of drainage model. For future precipitation, high resolution climate change information has been generated using moderate emission scenarios SRES A1B derived by REGCM3 regional climate model. Sea level rise information from secondary sources has been added with 20 year return period to simulate the future scenarios. DEM of 10 m resolution has been used to delineate catchment and drainage network of the study areas. It has been found that many secondary canals are not capable to carry design storms. Also, the inundation area will significantly increase from baseline to 2030s and to 2050s in the study areas.