IJEP 42(6): 643-651 : Vol. 42 Issue. 6 (June 2022)
Pallavi Tyagi*
Indian Institute of Technology, Department of Humanities and Social Sciences, Mumbai-400 076, Maharashtra, India
Abstract
In India, Mumbai city faces the problem of recurrent urban floods. The Mumbai floods of 2005 highlighted the vulnerability of the city to increasing climate change threats. On its face, the causes of the 2005 floods were attributed to heavy rainfall and inadequate drainage system. However, various environmentalists argued that the deterioration of the natural ecosystem,, such as the mangrove’s destruction and Mithi river degradation, were crucial factors in causing the disaster. Also, few empirical studies showed that mangroves could have decreased the impact of 2005 floods by dissipating the incoming wave energy near the coastline. Hence, this paper aims to study mangroves’ role in mitigating the urban flood risk in the H east ward (study area) of Mumbai. The study evaluates the landuse-landcover (LULC) changes in the hydrological processes over time. As the H/E ward lies in the Mithi river catchment area, we processed the digital elevation map (DEM) and used the soil conservation service-curve number (SCS-CN) and kinematic routing method to generate the peak discharge at the river sub- basins in hydrologic engineering centre- hydrologic modelling system (HEC-HMS) software. The river geometry is prepared in hydrologic engineering centre-river analysis system (HEC-RAS) software and flood hazard maps were prepared. We found that there has been an increase of 1.40% in the flood inundation area from 1973 to 2005. The maximum depth at the banks of Vakola Nala (location near mangrove) was 1.77 m in 1973 and it reaches 2.36 m for the landuse in 2005. The results highlight the need to restore mangroves around the coastline to mitigate the risk of urban floods.
Keywords
Climate change, Ecosystem based adaptation, Mangrove ecosystem, Forest degradation
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