Extraction of detailed level flood hazard zones using multi-temporal historical satellite data-sets - a case study of Kopili River Basin, Assam, India

Kopili River Basin is one of the chronic flood affected basins of Brahmaputra River, lies in north-eastern part of India. This study attempts to utilize the historical spatial data on flood inundation layers derived from multi-temporal remote sensing images for identifying villages falling in various flood hazard severity zones. A total of 183 flood events were mapped in the basin in the last two decades. About 3.89 lakh hectares which is 29% of Kopili River Basin area is affected by floods during 1977, 1988 and 1998-2015. The flood hazard zonation frequency is determined treating each village as minimum unit of entity and based on the number of times affected by flood events in a given year. About 742 villages are categorized as very low to low and 396 villages fall in moderate flood hazard zone and more than 150 villages are categorized between high to very high flood hazard zones.