Uncertain climate and socio-economic change: trade-offs for plans and priorities in an African transboundary basin

Abstract:

Over 90% of Malawi’s electricity generation and most of its irrigation depend on Lake Malawi outflows into the Shire River. Infrastructure plans upstream and downstream of Lake Malawi depend on the satisfaction of key criteria; maintaining lake levels above outflow threshold and below lakeshore flooding threshold, and meeting Shire river needs for hydropower generation, irrigation and environmental flows for a biodiverse Ramsar wetland. In this study, we apply a decision making under uncertainty approach to explore uncertain climatic and development futures, and their implications for Malawi’s water, energy and food security. We force a stakeholder-validated Water Evaluation And Planning model with 29 bias-corrected climate model projections and two development pathways; a stakeholder elicited pathway and a water demand intensification pathway. We incorporate operational management changes at the Kamuzu Barrage (controls outflows from Lake Malawi into the Shire River) into the model. We find that upstream irrigation expansion in Malawi and Tanzania exacerbates climate change driven lowering of lake levels, including scenarios of no outflow from Lake Malawi. Barrage operation changes reduce lakeshore flooding risks, but do not adequately address the risk of no outflow. While low lake levels adversely impact Shire River hydropower generation and irrigation needs, extremely high lake levels under some projections could lead to lakeshore and downstream flooding. Results demonstrate how trade-offs emerge between satisficing key criteria under uncertain future changes, and reveal how uncertain climate and socio-economic futures could affect water resources availability and pose risks to Malawi’s water, energy and food security.