Energy and agricultural water conservation at scale in the transboundary Incomati River Basin

In many transboundary basins, irrigation, domestic, and industrial water uses are growing. In this study we use a detailed multi-sector river basin simulator (Pywr) to assess whether decommissioning thermal power plants and increasing irrigation efficiency basin-wide could save enough water to support planned growth of the domestic, agriculture, and environment sectors in the Incomati river basin (shared by South Africa, Mozambique and Eswatini). Results revealed that given estimated future demands and a range of plausible hydrological scenarios, on average reducing water abstraction by 14% through thermal generator decommissioning and irrigation improvements led to 7 GWh more potential hydropower energy per year and enabled a 50% decrease in the number of years where river flows violate an estuary ecological flow threshold. However, given expected demand growth, these water conservation measures were insufficient and water deficits averaged 65 million cubic metres per year. Future increases in water abstraction without improved transboundary coordination may further undermine any water savings. To support responses to increasing water scarcity, the model is deployed within an online user-interface so that basin agencies from different countries can securely share the model and collaboratively examine different scenarios of future water management.