Promoting Regional Security by Enabling Cooperative Management of the Nile River Basin through an Integrated Hydrologic Modeling Framework

The Grand Ethiopian Renaissance Dam (GERD) is currently under construction on the Blue Nile River. There is a possibility for tensions to increase between Egypt, Ethiopia, and Sudan over the impending filling of the GERD reservoir. Climate variability will likely determine the downstream impacts to Egypt and Sudan. Cooperative management will be key to mitigating conflict. Reliable objective forecasting is needed for trilateral cooperation. A U.S. government Interagency Water Working Group (IWWG) Science and Applications Team (ISAT) is working to demonstrate technologies that advance understanding and decision-making related to transboundary waters by making water data transparent and facilitating information sharing. This effort aims to create a framework that links hydrologic models, e.g. the NASA Land Information System (LIS) and U.S. Army Engineer Research and Development Center Streamflow Prediction Tool (SPT), to provide information related to flows across an entire basin in real-time with forecasting. The Nile River Basin was selected for a pilot study to use the proposed framework to estimate the hydraulic loading on GERD under various filling scenarios. Daily runoff estimates from the Noah and Joint U.K. Land Environment Simulator (JULES) Land Surface Models in the LIS were passed to the SPT river routing component to estimate daily streamflow dynamically for the entire Nile River System. These hydrologic flows are associated with meteorological forcings from various climate reanalysis products, e.g. Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS)/Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) & WATCH Forcing Data methodology applied to ERA‐Interim reanalysis data (WFDEI). This produced streamflow estimates that were well correlated with available observations (R=0.96). The streamflow results were then used to analyze various GERD filling scenarios based on a stage-storage relationship for the reservoir derived from a digital elevation model. These scenarios considered a number of different hydrologic regimes informed by IWWG experts familiar with the complex water policy issues in the basin. The GERD case study demonstrates that this integrated modeling framework can address water security challenges globally and enhance understanding of the entire system, particularly in data sparse areas involving transboundary rivers.