Ecosystem-based approaches for flood risk reduction: Advances in their comprehensive evaluation using the case of the Ouémé River Basin in Benin

Abstract

Floods are amongst the most frequent and widespread disaster worldwide, posing enormous development challenges. Also in West Africa, flood risk still needs proper addressing. Ecosystem-based disaster risk reduction (Eco-DRR) approaches are increasingly recognised as cost-effective part of the solution, providing ecosystem services that reduce all three components of risk, namely hazard, exposure and vulnerability. Indeed, Eco-DRR, such as floodplain restoration or agroforestry, can affect hydrological processes, altering the flood hazard and exposure, and provide ecosystem services that reduce people’s vulnerability to floods and/or enhance their adaptive capacities. To fully understand the impact of Eco-DRR on the three components of risk, it is thus important to take an interdisciplinary approach to the assessment of Eco-DRR. Yet, there remains a substantial gap in the comprehensive evaluation of Eco-DRR effects, including guidance on how to depict the flow of ecosystem services and their benefits to people, which undermines the effective use of Eco-DRR measures in flood-prone environments.Using the case study of flood risk in the Ouémé River Basin, this contribution will share advances in the comprehensive evaluation of Eco-DRR measures. After defining locally-relevant Eco-DRR measures based on administrative plans, the scientific literature, and expert surveys, a systematic literature review has been conducted to understand the impact of selected Eco-DRR measures on both hydrological processes and ecosystem services provisioning, so as to evaluate the Eco-DRR measure against its effects on all risk dimensions. For the hazard, the hydrological model SWAT is used, comparing the flood hazard under different land use and land cover change scenarios. Preliminary results, with a focus on the Eco-DRR measure of agroforestry, and lessons learnt will be presented in the session.