Flood risk index development at the municipal level in Costa Rica: A methodological framework

Abstract

Floods constitute one of the most damaging natural hazards in the world. Seasonal and extraordinary rainfall recurrently trigger different types of floods in Costa Rica. An integrated and efficient flood risk management requires comprehensive understanding on the flood driving variables. This study analyzes and classifies the 82 Costa Rican municipalities in terms of hazard, exposure, and vulnerability to floods. Then, an index for flood risk is designed to comprehend the risk driver’s role (hazard, exposure, and vulnerability) at a local level. The present method provides a flood risk index on a municipal scale done through a statistical validation of different sources of municipal-level data. Higher flood risk values mostly occur in municipalities located in extensive flatlands, medium to large areas in both the Pacific and Caribbean basins, as well as borderlands and coastal regions. The results can promote flood risk assessment plans in developing countries or regions where baseline information is limited. This approach has been absent in most of the national flood risk policies, specifically the plans analyzing the likelihood of short, mid, and long-term decline of risk conditions influencing flood disasters.