Analysis of Flood Risk and Strategic Management to Address Its Adverse Impacts: A Case Study of the Boudouaou Basin, Algiers, Algeria.

Abstract

Flooding is a significant and worsening challenge for many human societies, with increasing severity driven by climate change and land use pressures. This natural hazard constitutes one of the world's worst natural disasters, causing about a third of all significant human, material, and economic losses, highlighting the urgent need for effective flood risk management strategies. This study assessed the flood risk in the Wadi Boudouaou basin using an integrated approach that combines the Analytical Hierarchy Process method and the Rainfall Runoff Inundation Model to identify high-risk areas. The AHP method was applied to develop a flood vulnerability map based on seven key criteria: elevation, slope, rainfall, land use/land cover, drainage density, topographic wetness index and distance from river to provide a spatial understanding of areas with varying susceptibility to flood impacts. The RRI model was used to simulate flood hazard under two major scenarios: with and without the presence of the Keddara Dam. However, the presence of the dam produced negligible differences in flood hazard patterns. Furthermore, four rainfall conditions were tested: the actual recorded event, and hypothetical increases of 20%, 60%, and 100% to simulate the effects of future climate change. Analysis of the risk map illustrates that the areas situated in proximity to the main Boudouaou Wadi exhibit very high to high risk to flooding incidents compared to other parts of the watershed. Additionally, the results showed that flood risk increases significantly with higher rainfall intensities, particularly along main river channels and low-lying floodplains, emphasizing the pressing need for proactive flood risk management measures. the findings will provide policymakers, urban planners, and disaster management authorities with actionable strategies to reduce flood risk and enhance long-term resilience in the Wadi Boudouaou Basin.