FLOOD INUNDATION MAPPING OF URBAN CATCHMENT USING HYDRO DYNAMIC MODEL

Abstract

Mitigation of urban floods and waterlogging, majorly in metropolitan cities, has drawn recent attention due to aggravated flooding in cities hindering socio economic activities and ecology. The complexity of urban floods can be attributed due to rapid urbanization and extreme climatic events. The encroachment of water bodies and drains, unplanned construction, and destruction of natural storm conveyance need to be acknowledged to improve the drainage system to varying climatic conditions. Therefore, this study was carried out to address the inadequacy of the storm drainage network in Zone-IV GHMC (Greater Municipal Hyderabad Corporation), Hyderabad, Telangana. Environmental Protection Agency’s (EPA) SWMM (Storm Water Management Model) software has been used to simulate the runoff in integration with the GIS application. Five tipping bucket rain gauges and three automatic water level recorders were installed in the pilot area for collecting the observed data. The model was simulated with different LULC periods from 1973, 1990, 2000, 2005, 2010, 2015, and 2020 and positive correlation between peak discharges, runoff coefficient, runoff depth, and percentage impervious area and find out the pilot area runoff coefficients (0.869, 0.851, 0.894, 0.903, 0.910, 0.925 and 0.956). The model simulated the runoff depth flood event for more than 100 years return period on 13 October 2020 and generated the flood inundation map using HEC RAS. Flood inundation depths are well compared with field observation marks. The dataset, the results obtained and the methodology followed in the current study can be used by urban planners to identify the potential flood risk zones and nodes and incorporate them to plan the mitigation and management strategies.