Analysis of Urbanization-Induced Flooding in the Koramangala-Challaghatta Valley of Bangalore City Using Remote Sensing and GIS

The Koramangala-Challaghatta valley of area approximately 246 sq. km in Bangalore city is one of the three major watersheds, dividing the greater part of the urban city area into separate and distinct drainage zones. The valley has enclosed ponds and lakes and most of the southern and eastern city runoff goes into these water bodies and finally into the Dakshina Pinakini River. Major multinational IT companies have their offices in this region and the area is densely populated. Remote Sensing and Geographic Information Systems technology help in studying and analyzing real-time data through satellite image data sets, topography, related land use land cover changes along with catchment area analysis, runoff studies, and drainage patterns. Satellite data from Cartosat and Resourcesat has been studied along with Digital Elevation Model data and Survey of India toposheets. Land use and land cover in the city have seen a decrease of more than 90% in the vegetation cover since the past five decades, that being converted to built-up areas. Rainfall data from 1965 to 2022 has been studied and analyzed. The total rainfall Bangalore receives every year has seen a steady increase since the past 2 years, with percentage deviation from normal being 28% in 2020 and 33% in 2021. This paper has addressed the analysis of urbanization-induced flooding in the Koramangala-Challaghatta valley, and how it can be controlled and mitigated.