First-ever environmental flow assessment in Benin successfully completed

How much water from the Ouémé river in Benin should be reserved to maintain important ecosystems and biodiversity in the Ouémé Delta? Benin’s first-ever environmental flow assessment, carried out by local experts with support from IUCN NL, provides the answer. The experts recently presented their findings to decision-makers, in order to allow them to plan for water allocation and aquatic infrastructure in the river basin without jeopardizing the integrity of important ecosystems.  

Header photo: © Elke Praagman, Ouémé River Basin in Benin

In the Ouémé River Basin, there are plans for dams and large water abstractions, which will alter the hydrological regime of the Ouémé River. If not planned properly, these developments will impact important ecosystem services such as fisheries, fertile soils, flood retention and water quality downstream in the Ouémé Delta.

By determining the environmental flow requirement in the Ouémé Delta, it is possible to reserve this part of the river flow for important ecosystems and their functions for nature and people. This way, it is clear how much water can be withdrawn for other uses whilst maintaining biodiversity in important ecosystems, including the goods and services we derive from them.

“Large irrigation, hydropower development and infrastructure projects are already affecting the frequency and quality of floods in the Ouémé Delta,” says Fidèle Sossa, director of the Beninese NGO AquaDeD. “Together with climate change, they constitute the main threats to ecosystem services linked to flows.”

Defining water allocation

Especially when planning for water allocation in the river basin for hydropower, irrigated agriculture and other large-scale water using activities, the results from the environmental flow assessment will define the maximum amount of water that can be allocated without compromising the functioning of important ecosystems.

It is important to include the results of the Environmental Flow Assessment in the water management plans of the Ouémé River Basin. “The environmental flow assessment is a compass and an important tool to manage the current developments in the Ouémé River Basin. We presented our findings to decision-makers, so they can take environmental flows into account in the legal and institutional framework for these developments,” says Sossa, who is part of the research team for the Environmental Flow Assessment, together with IUCN NL’s partners from NGOs CREDI and BEES and the National Water Institute of Benin and with technical assistance of IHE Delft.