Flood susceptibility mapping of the Western Ghat coastal belt using multi-source geospatial data and analytical hierarchy process (AHP)

Abstract

Progressive environmental and climate change have altogether expanded hydro-meteorological hazards everywhere throughout the world. In recent times, floods have gained increasing global significance as a result of their destructive nature and for causing monetary and human losses. Hitherto, flood mapping studies in India have been profoundly constrained because of the absence of a comprehensive database coordinating flood attributes, for example, peak discharge at river gauges or geospatial data. The present investigation, for the first time, applies a large number of multi-sourced environmental flood conditioning factors (viz. elevation, slope, distance from drainage, drainage density, flow accumulation, topographic wetness index, rainfall, land use, soil texture, topographic ruggedness index and geology) and socio-economic parameters (viz. population density, literacy rate, literate population density, and road density) using the analytical hierarchy process approach to prepare flood susceptibility, vulnerability, and flood risk maps of the entire Western Ghat coastal belt, India. Essential findings of this study demonstrate that a critical percentage of area is involving high (28%) and very high (22%) flood susceptibility. About 25% area shows high flood risk and these regions need immediate attention. Efficiency testing of the flood susceptibility map indicates high precision, utilizing area under the curve (AUC) through a considerably high value (0.84). The output flood risk map can be useful for planners, managers, and regulatory bodies to manage and mitigate flood incidents along the Western Ghat rivers. Even though the methodology applied in this study is highly simple, yet it shows high accuracy, and subsequently, can be utilized in other regions for expert knowledge-based flood mapping.