Elucidating hydropower impacts on fish biodiversity across African rivers

Despite relevant environmental, social, and financial risks, developing countries are increasingly pursuing hydropower development, including 300 new hydropower projects planned in Africa for a total of around 100 GW of new installed capacity. African rivers, however, are among the most biodiverse ecosystems. Their unique biodiversity might be in peril as hydropower projects are generally designed according to techno-economic considerations, with limited consideration of environmental aspects.

In this work, we develop an integrated modeling framework to explore synergies and trade-offs associated with alternative hydropower development strategies in Africa. Specifically, we first investigate alternative options for hydropower development through the soft-link of a surface water quality model (i.e. DYNQUAL) with an energy system planning model (i.e. OSeMOSYS-TEMBA). The former simulates river discharge and water temperature at a 5-arcminutes resolution across the African continent; the latter identifies least-cost power capacity expansion plans where hydropower generation is conditioned on the simulated water availability at each power plant site. Then, we combine the DYNQUAL model simulations incorporating the selected hydropower projects to estimate the regulated dynamics of river discharge and temperature with the GLOBIO-Species model, which allows assessing the impacts on African freshwater fish biodiversity. The analysis is conducted for historical as well as projected socio-economic and climate conditions using a multi-model ensemble that includes different combinations of Shared Socio-economic Pathways and Representative Concentration Pathways.

Preliminary results show that fish biodiversity has been already impacted by the existing hydropower infrastructures. Over the next decades, these negative impacts will be amplified. Most of these impacts can be attributed to the increasing water temperature associated with climate change, while the construction of additional hydropower plants appears less important.