Flood susceptibility mapping in the Bilate catchment, Ethiopia

Abstract

Flood susceptibility mapping plays a key role in planning flood mitigation. Floods may not be avoidable due to the future climate changes. The Bilate catchment in Ethiopia is vulnerable to flood disasters and it is used as case study in this project. The analytical hierarchy process (AHP) under multi-criteria decision analysis (MCDA) is used to develop the flood susceptibility map of the Bilate catchment. It was accordingly found that factors such as slope, rainfall, land use/land cover (LULC), elevation, topographic wetness index (TWI), soil type (ST), sediment transport index (STI), drainage density (DD), stream power index (SPI), and distance from the river (DR) have significant effects on the flood intensity in Bilate catchment. Each factor was evaluated by AHP, and an output map was developed in ARCGIS. The prepared flood susceptibility map was classified into five classes such as very low, low, moderate, high, and very high 9.3%, 32.6%, 41.2%, 10.8%, and 6.1% areas respectively. The flood susceptibility map reported in this research is a great resource for relevant parties, including government and non-governmental organizations, to evaluate the impacts of flooding in the Bilate catchment and throughout the nation. The flood identified in this research may also be used as a reference to flood-related studies. HIGHLIGHTS Maps of flood susceptibility are created using proxy data and multi-criteria decision analysis (MCDA).; The key elements that significantly contribute to the flood phenomenon are land use/land cover, rainfall, slope, and elevation.; Flood susceptibility ranged from very high to very low throughout the whole Bilate catchment.; An early warning system could make use of the flood susceptibility map produced in this study.;

Keywords

• ahp
• climate change
• flood-causing factors
• flood risk
• mcda