Analysis of flood susceptibility and zonation for risk management using frequency ratio model in District Charsadda, Pakistan

Abstract

This study focuses on the analysis of flood susceptibility and resultant zonation for risk management using frequency ratio model in District Charsadda, Pakistan. To achieve the study objectives, a reconnaissance survey was conducted, and frequent flood inundated areas were identified in the study area by interpretation of Landsat 7 image together with the intensive field survey, a total of 161 flooded locations were demarcated at different part of the district with handheld GPS. As a result, an inventory of spatial database of past flood inundation was generated and role of all the influencing factors for detecting the extent of flood susceptibility. During flood susceptibility analysis, ten conditioning parameters including: elevation, slope, aspect, curvature, plan curvature, profile curvature, proximity to roads, proximity to streams, proximity to river and land use/land cover were selected. A correlation between conditioning factors and flood was calculated using frequency ratio method. Consequently, the summation of frequency ratio values was taken for all the parameters for development of flood susceptibility index. The flood susceptibility index was then classified into five zones of very low (27.64%), low (39.88%), moderately susceptible (22.25%), high susceptible (7.78%), very high (2.46%). For accuracy assessment, flood density approach has been applied to compare the zones of susceptibility with the past flooded areas. As a result, the predication accuracy was found 77.3%. The flood susceptibility zones could be used for flood risk management and land use planning for minimizing the potential risk in the floodplain of rivers flowing through the study area.