Analysing flood risk zonation using analytical hierarchy process (AHP) in Bhagirathi basin, India

Abstract

Flood is a very commonly occurring disaster in Bhagirathi Basin. As a result, many people lost their life & properties. Proper flood control management is required to get out of this problem. It is not possible to fully control the flood damages. But by taking some physical measures, it is possible to prevent the flood damage to some extent. Identification of flood zone is very much essential for this reason. So, flood vulnerability and risk assessment are crucial strategies. Some physical and social parameters are selected to calculate. Those parameters are most influential during the flood. To evaluate flood vulnerability and risk zonation Analytical Hierarchy Process has been used, which is a beneficial process for evaluating flood risk zonation. So, the objective of this study is to assess flood risk zonation using the analytical hierarchy process in the GIS framework. The parameters considered for flood hazard are Drainage Density, Distance from River, Elevation, Slope, Topographical wetness Index, Modified Normalized Difference Water Index (MNDWI), Roughness, Rainfall, Modified Fournier Index (MFI), Normalized Difference Vegetation Index (NDVI), Soil and Sediment Transport Index (STI). And the parameters taken for Vulnerability Assessments are Total Population, Child population Under six years of age, Total female population, Distance from flood centre, Land Use Land Cover (LULC), Distance from Hospital, Distance from Road, Road Density, Illiteracy Rate and Employment Rate. The map has been prepared for each parameter, and a pairwise comparison matrix is prepared to calculate the weightage value for each parameter, which is applied in the AHP process. The result of this analysis shows that lower region of the basin is most susceptible, vulnerable and risk zoning area, due to low range value of distance from river and high value of drainage density. All most 60% area of the lower region is highly flood susceptible, 40% are flood vulnerable and almost 25% are risk zoning area. So, in future this study will help to build and implement various Government policies during flood. Keywords: Flood; Analytical hierarchy process; Hazard; Vulnerability; Risk