Geoinformatics and AHP multi criteria decision making integrated f lood hazard zone mapping over Modjo catchment, Awash river basin, central Ethiopia

Abstract

Flood hazards are natural disasters that profoundly influence the environment and society. To effectively control the incidence of flooding, it is crucial to identify and map regions susceptible to flooding. The Modjo catchment is frequently hampered by flooding, making it crucial to map and identify flood hazard zones. This study aimed to identify and locate the flood hazard zones of the Modjo catchment employing the integrated use of multi-criteria decision-making and geoinformatics tools. Ten influencing factors were used to develop flood hazard zones: drainage density, curvature, rainfall, distance from the river, soil type, elevation, slope, topographic wetness index, land use/cover, and the normal ized difference vegetation index. Subsequently, raster-formatted thematic layers of these influencing elements were created, and appropriate weighting was assigned based on their relative responses to the occurrence of flood events and overlayed using the overlay GIS spatial analysis tool. The flood hazard potential zone in the study area was generated and classified into five groups: negligible, low, intermediate, high, and severe. According to the results, the negligible, low, intermediate, high, and severe zones were represented by 0.686% (9.74 km2), 16.73516% (237.5649 km2) 74.12% (1052.28 km2), 8.44% (119.94 km2), and 0.0012% (0.018 km2), respectively. The weighting and ranking processes are well reflected in the final flood hazard zone map. The results revealed that a substantial area of the catchment is at risk. Ulti mately, 29 observed flood datasets were used to confirm the outcome, yielding an accuracy of > 75% and an area under the ROC curve of 0.868. Most of the flood point data were found in high and severe regions. Considering the verified results, relevant organizations should participate in creating sustainable management plans.