Spatiotemporal flood hazard and flood risk assessment using remote sensing techniques. Case study: Khartoum State, Sudan

Abstract

The state of Khartoum being the most populated state in Sudan, faces the consequences of floods recurrence almost annually during rainy season. Policy makers and on ground NGOs need to tackle the hazard of floods in an effective and efficient manner. Recent research demonstrated the capabilities and potentials of remote sensing in flood hazard and risk mapping. This study aims to map flood hazard and assess the risk of floods in state of Khartoum, Sudan. In order to identify the flood hazard in state counties, an inundation indicator is used, namely the relative frequency of inundation (RFI). Flood events that occurred from 1988 to 2018 were mapped using Landsat satellite images, and maximum flood extent was then delineated. RFI was obtained using maximum flood extent maps and served as the flood hazard map. We developed a Land Cover Land Use (LCLU) map using Landsat 8 to identify affected urban and croplands areas in the state of Khartoum. RFI values was used along with LCLU map to assess state counties, and to assess the vulnerability of public facilities (health and educational facilities) using zonal statistics. It was demonstrated that, in terms of average RFI values for LCLU classes per county, croplands had the highest flood hazard, and Urban areas carried a relatively moderate flood hazard. The results of this study indicate that croplands on the riverbanks are the most inundated areas in the state of Khartoum, and the most urbanized counties have the highest flood hazard.