9. Flood Mapping and Prediction Using FLO-2D Basic Model

This study attempts flood simulation, in a simple and economical way, in the region covered by the bounding box (study area) of the flood prone Ghatal block of West Bengal. Only, the hydrograph of the Silabati river, and the SRTM (Shuttle Radar Topography Mission) DEM (Digital Elevation Model) of the study area, are used as inputs. Simulation is done with the FLO-2D Basic Model, and the resultant flood simulation map (for simulation time: 24 h), when compared with the maps of the roads and the settlements, in the study area, prepared from the LISS-III (Linear Imaging Self-Scanning System-III) image, reveals that mostly the southwestern part of the study area will be affected. Calculations show that, around 40 km² will be inundated with water level >1 m, and around 62 km² will be inundated with water level ≤1 m (Ghatal block’s total area is nearly 230 km²). The flood simulation map, and the maps of the roads and the settlements of the study area, are published in GeoServer; hence these maps are ready to be accessed through the web services. The accuracy of the flood simulation is tested by using five actual flood maps, pertaining to 2011, 2013, 2015, 2016 and 2017, which are obtained from Bhuvan; calculations show that approximately 76.43% of the area of the simulated flood is covered by the total inundation depicted in these actual flood maps. Hence, there is a good correlation between the simulated and the total actual inundations.