Adaptive river system and economy-wide planning framework for Nile water resources management

Climate change is projected to affect precipitation and evapotranspiration over the Nile Basin, resulting in modifications to streamflow, irrigation water demands, and evaporation from open water bodies. Future socioeconomic pathways are a key input to climate change projections as they incorporate assumptions regarding economic systems through population and economic growth and climate policies. However, there are huge hydrological and socioeconomic uncertainties and the complex interlinkages of the climate, hydrological, river, and economic systems represent a challenge for planning a resilient future. This study introduces a planning framework for designing adaptive management plans for the Nile infrastructure system. The framework combines climate change projections from CMIP6, a semi-distributed hydrological model, a river infrastructure system model, economy-wide models of Ethiopia, Sudan, and Egypt, and a multiobjective design algorithm. The framework's hydrological, river system, and economy-wide components are linked to the climate projections, ensuring coherence in socioeconomic development. The multiobjective design algorithm provides the ability to search for efficient adaptive management plans for Nile infrastructures. The adaptive planning framework was used to design efficient options for an adaptive management policy of the Grand Ethiopian Renaissance Dam (GERD), considering economy-wide and river system interests of Ethiopia, Sudan, and Egypt in 2020-2045. We compared the performance under the adaptive policy designs to the performance under a recent proposal discussed in Washington, D.C. Results show that under an example compromise solution, the mean discounted real GDP increases by 0.77, 0.67, and 0.18 billion USD in 2020-2045 for Ethiopia, Sudan, and Egypt, respectively, compared to the Washington Draft Proposal. These economic benefits are higher in extreme climate projections, with rises in discounted real GDP of up to 15.8, 6.3, and 3.0 billion USD over 2020-2045 for Ethiopia, Sudan, and Egypt, respectively.