Flood inundation modeling under present and future scenarios of mean sea levels for the Hub River watershed. (2nd January 2017) - Bakhsh, Hafiz Ahmad
Abstract: Climate changes, such as global warming, changes in precipitation patterns, shrinkage of glaciers, and increases in mean sea levels, are occurring worldwide. Mean sea level rises caused by the thermal expansion of oceanic water and the melting of glaciers at high rates are a potential source of flooding in coastal cities. This paper describes the extent and depth of flooding in a region of Karachi City, Pakistan that lies within the catchment area of the Hub River. Flooding scenarios under present conditions and future scenarios of mean sea level rises expected from global warming were simulated. The Institute of Industrial Sciences Distributed Hydrological Model was employed to calculate flood flow and depth. The model was calibrated and validated for the 2007 and 1977 rainstorms that occurred at Hub Bridge and Bund Murad Khan, respectively. The simulated results agree well with the observed river stages. Flood inundation maps for 1977, 2007, 2025, 2050, 2075, and 2100 were prepared. The results on future scenarios reveal that mean sea level rise in the next hundred years will not increase flood inundation depths within the simulated watershed boundary of the Hub River. Nevertheless, these findings should be interpreted with caution given that coastal flooding due to changes in future precipitation patterns and tsunamis were not included in the simulations.