GIS-based flood susceptibility analysis using multi-parametric approach of analytical hierarchy process in Majuli Island, Assam, India

Flood is a natural disaster that impacts each and every sector of a society directly or indirectly. The geography of Assam makes it a suitable land for flood which is a recurring phenomenon affecting thousands of people every year. In order to reduce the flood menace and minimize the impact of flood, flood susceptibility analysis and proper flood management becomes vital. The present study was carried out to analyze the susceptibility of flood using GIS with multi-parametric approach of analytical hierarchy process in Majuli Island of Assam, which is constantly being degraded over the last few decades. Ten flood conditioning factors, viz. elevation, slope, topographic wetness index, land use and land cover, rainfall deviation, distance from the rivers, normalized difference vegetation index, drainage density, clay content in soil and distance from road were considered and their spatial maps were prepared using ArcGIS 10.3 for mapping of flood susceptible zones. AHP modeling was used to calculate the weightage of each factor and overlay analysis was performed. From the study, it was found that nearly one-third of the land area (30%) was under very high to high susceptible zone (128.84 km2). 62.19% of land was found under moderate susceptibility and 7.71% was under low susceptible zone. The spatial analysis revealed that the southwestern part of the island is mostly susceptible to floods. The susceptibility map may provide vital information to the researchers as well as the government to adopt specific measures in different flood susceptible zones to minimize the flood occurrences and their hazardous impacts.