Flash Flood Susceptibility Analysis At Sub-Watershed Level Using Morphometric Ranking Approach (Mra) In District Khyber, Pakistan

Abstract

Flash floods frequently occur in District Khyber which causes widespread losses of life and property. The current study analyzes flash floods at the sub-watershed level using the morphometric ranking approach (MRA). The ASTER GDEM acquired from the open source (https://search. Earthdata. Nasa. gov) has been processed using Arc Hydro Tool in ArcMap 10.8. Nineteen geo-morphometric parameters have been derived and were utilized in this research. The district has been delineated into 15 Sub-Watersheds (SW-1 to SW-15. Based on the Morphometric Ranking Score, the sub-watersheds are classified into three classes- highly susceptible, moderately susceptible, and low susceptible sub-watersheds. Based on the MRA, the SW-1, SW-2 SW-6, SW-7, SW-1, S[1]W-12, and SW-13 are included in the high flash flooding susceptible zone. These seven Sub-watersheds cover an area of 745.4 Km², which accounts for 46.66% of all the sub-watersheds. The moderate flash flood hazardous sub-watersheds include SW-3, SW-8, SW-10, and SW-14. The zone of moderate flash flood susceptibility covers an area of 334.44 km² which accounts for 26.67% of all the Sub-watersheds of the study area. This includes those sub-watersheds which have morphometric ranking scores between 49-54. The low flash flooding susceptible Sub-watersheds include SW-4, SW-5, SW-9, and SW-15 (26.67% of the total sub-watersheds) covering an area of 255.96 km². The cumulative MR score of these Sub-watersheds ranges between 41-48. It is anticipated that flash flood hazard modeling, analysis, and mapping will help the locals and the concerned departments to chalk out effective flood mitigation strategies for sustainable development.