Unguarded refugees of deep waters: flood vulnerability analysis of Kosi embankment through the lens of hydro-geomorphological and socio-economic parameters through GIS analysis

The Kosi River basin is one of the most flood-affected regions in India. The first victims of these frequent floods are nearly 8 lakh people stranded between the Kosi river embankments in the Saharsa and Supaul districts of Bihar. These individuals face a trifecta of issues, including regular flooding, scarcity of basic amenities, and loss of livelihood, all of these are exacerbated by climate change impacts. The population living outside, too, had no respite due to frequent embankment breaches and waterlogging due to these structures. The region went through numerous flood-related research based on geomorphology, hydrology, and other physical factors; however, the flood impact assessment of embankments and its role within the socio-economic dimension remains unexplored. The present study unpacks flood vulnerability in 283 villages within the Kosi embankment. The study combines and analyzes thirteen attributes, including eight socio-economic and five hydro-geomorphic parameters, incorporating Sentinel-2, IMD, FMIS, and the 2011 census report and other survey reports. It employs GIS analysis to develop a socio-economic, hydro-geomorphic, and composite vulnerability map based on the weightage assigned to the aforementioned attributes. The analysis highlights that nearly the entire population in the embankment region is susceptible to the effects of flooding, with ?66% of the region having high and very high flood risk and ?26% in areas with moderate risk. The study�s outcomes could contribute to directing the effects and exclusion created by flood control infrastructure. They can also help to develop a comprehensive flood adaptation and resilience program for the Kosi River basin.