Assessing Flood Susceptibility using Geospatial Techniques and Analytical Hierarchy Process in an Indian Catchment

Being a natural calamity, flood poses serious threat to the livelihood of all living beings. Due to the adverse effects of climate change and anthropogenic activities, significant changes in the occurrence of extreme floods are happening day-by-day. An accurate flood susceptibility map plays a crucial role to adopt proper adaptation and mitigation strategies in protecting the vulnerable communities. This study performs a flood susceptibility mapping of the Jagatsinghpur district lying in the delta region of the Mahanadi River basin in the eastern part of India. This river basin has suffered from numerous recurring floods of variable extremities since the 1960s. A major concern arose when the frequency of extreme floods in this delta increased drastically post the 2000s. This study considered several key factors affecting flood occurrence like rainfall, topographic wetness index, land use/land cover, distance from river, elevation, slope and drainage density. The map layers of all these factors are integrated in the Geographic Information System (GIS) platform, wherein the Analytical Hierarchy Process (AHP) is used to develop and evaluate the flood susceptibility maps. The findings suggest that more than one-third of the study area falls into the low to high flood susceptibility zone. Nearly 40% of the area is under very low to low zone, and a small portion fell under the high to very high flood prone zone. The study serves as a preliminary study towards flood risk management and provides critical insights for the decision makers to develop appropriate disaster risk reduction strategies and strengthen the flood management policies.