Flood Hazard Zone Mapping of Kasari River Basin (Kolhapur, India), Using Remote Sensing and GIS Techniques

Flood is the most ubiquitous environmental hazard on the earth perhaps because rivers are the most dominant geomorphic agent in the present geological epoch. The actual process of flooding is the outcome of a complex set of control factors where nature and humans play a conjoint role. Unpredictable climate change with its weather phenomena increases the chances of disastrous events like floods, so it is a need to undertake in depth study using advanced techniques like GIS and remote sensing with accurate methods, including appropriate basin factors. The present study has identified the flood hazard zones of the Kasari River catchment, located in the Kolhapur District of Maharashtra. Remote sensing (RS) and geographic information system (GIS) techniques have been used for the attempted research work. Analytic hierarchy process (AHP) and weighted overlay analysis are the multi-criteria decision-making tools that have been used for preparing the flood hazard zone map of the Kasari River basin. A number of popular approaches to flood hazard mapping use DEMs, discharge data, and flood frequency data such as remote sensing, GIS, and hydrological data. As a phenomenon, flood is complex-caused by a multiplicity of factors-thus, this often overlooks its multidimensionality. This study used a multi-criteria decision-making tool, such as AHP, which has the added advantage of analyzing a large number of input parameters and their comparative analysis; this led to the identification of factors of relative importance. In order to create the map, twelve control parameters were calculated, viz. elevation, slope, distance from the river, flow accumulation, drainage density, topographical wetness index (TWI), stream power index (SPI), curvature, rainfall, land use/land cover, geomorphology, and geology. Among these parameters, elevation is the dominant factor that influences floods, followed by distance from the river. Both factors show a strong negative correlation of r = - 0.81 and r = - 0.70, respectively. Flooding is directly related to the drainage density of a river basin. High drainage density is directly associated with a higher probability of disastrous floods since it indicates high runoff from the surface. The stream network was extracted from the ASTER DEM and a drainage density map was created using the spatial analyst ArcGIS (10.8). This drainage density ranges from 2.2 to 3.8 km/ km(2) in the middle and downstream parts of the study area, which are more likely to cause flooding. Zones of very high flood vulnerability are located in the downstream region, i.e., in the eastern part of the basin. More than 50% of agricultural land and 16% of the settlement areas come under the zone of very high flood vulnerability. The high and moderate flood hazard zone affected areas are 23.05 and 32.11 percent, respectively, which is a cause for concern.