How water demand interventions can influence water management in the Nile River Basin

Climate change and population growth are exacerbating water scarcity, especially in river basins with arid climates such as the Middle East or North Africa, calling for the design of integrated water management strategies to reconcile competing water demands in interconnected Water-Energy-Food-Ecosystems (WEFE) systems and increasingly variable water supply. Understanding the WEFE Nexus is particularly challenging in transboundary contexts, where the interplay between different systems evolves over time with social-economic development and water system expansions as well as over space across multiple riparian countries. In this work, we explore the potential for integrating traditional water supply management strategies with novel technological solutions on the water demand side to mitigate existing tradeoffs and facilitate international agreements. Our approach is demonstrated in the Nile River basin, where we explore tradeoffs between power generation and irrigation water supply across Ethiopia, Sudan, and Egypt. We analyze innovative portfolios of interventions that combine the coordinated operation of large water reservoirs (i.e., the Grand Ethiopian Renaissance Dam, Merowe Dam, and High Aswan Dam) and the main irrigation diversions, and smart water demand management options in the Nile Delta including soilless agriculture and desalination plants. Soilless agriculture is an innovative agricultural technique characterized by lower levels of water consumption than traditional techniques because crops grow on a substrate (i.e., hydroponics) which can be combined with aquaculture to reuse the wastes from one system as nutrients for the other one (i.e., aquaponics). Desalination is widely used in many of the Middle East’s countries and offers the possibility to unlock the potential contribution of sea water in meeting the water demand of the coastal region. Our results show that the Nile River basin features both strong tradeoffs and notable synergies across the WEFE Nexus and across riparian countries, with the irrigation supply in Sudan playing a major role in allocating water between competing sectors. Notably, the potential reduction of the irrigation demands through different combinations of aquaponics, desalination, reuse, and groundwater pumping in the Nile Delta can contribute to mitigating existing tradeoffs and represents an additional option in the current international negotiations between Ethiopia, Sudan, and Egypt. Further technological improvements are needed for attaining large water demand reductions via soilless agriculture and desalination, which today cannot completely substitute low-quality water sources such as reuse and groundwater that induce relevant environmental risks.