Assessing flood inundation extent and landscape vulnerability to flood using geospatial technology: A study of Malda district of West Bengal, India

Assessment of flood risk zonation and landscape vulnerability to flood are fundamental aspects in flood risk management.Landsat 8 Operational Land Imager (OLI) and ASTER DEM data were used to assess landscape vulnerability to flood inundation and flood risk in Malda district of West Bengal state, India.Flood inundation map was prepared on the basis of water and non-water pixels on images (before and during the flood event).Flood risk map was prepared using equal interval of separation based on elevation and inundated flooded area.Flood inundation map was overlaid on the pre-monsoon land use/land cover map to produce landscape vulnerability to flood.The results revealed that 19% area of the district was flooded during monsoon flood event in 2014 and the agricultural area was most affected land use, sharing 62% of the total flood affected area, followed by river bed (21%), built up (7%) and vegetation (5%).The flood risk map of the district shows that temporary river islands, sand banks along the Ganga river course lie in low flood plain and were considered under high risk zone.The flood plain alongside minor stream drainage in southern, north-western and in between them comes under medium flood risk zones.Flood risk is low in areas which are away from the rivers.Non flooded areas were identified in high lands of eastern region of the district.Landscape vulnerability map shows that the blocks located along the Ganga river namely Kaliachak I, Kaliachak II, Kaliachak III, Manikchak, Ratua I were highly vulnerable to flood.The study suggests that efforts should be made to remove the sediments for increasing the depth of river.Spurs and bed bars should be constructed to avoid great loss of prime agricultural land, property and lives of people.