An integrated basin-wide water resources model for comprehensive assessment of water availability in the Nile River Basin

Abstract Despite extensive research on the Nile River Basin, few studies represent the entire basin as a connected hydrology–infrastructure–demand system. Existing basin-wide models are either dated, not openly accessible, or limited in their integration of hydrological processes, infrastructure operations, and spatially distributed water demand. To address this gap, this study aims to provide a contemporary basin-wide representation of how hydrology, major water infrastructure, and spatially distributed sectoral demand interact across the Nile. An integrated basin-wide model was developed in the Water Evaluation and Planning (WEAP) system for the 1981–2020 period using updated hydroclimatic data and contemporary infrastructure, land-use, and water-use information. Calibration and validation demonstrated strong model performance, with R 2 values above 0.79, NSE values above 0.77, and PBIAS below 11% at stations with continuous records, while long-term seasonal flow patterns were reproduced at data-scarce locations. The model was used to quantify and spatially partition the basin’s total renewable water resources. Basin-wide sectoral water demand for 2020 was also evaluated by harmonizing and scaling datasets from multiple sources. Results indicate that the basin receives an average of 2,109 billion cubic metres (BCM) of rainfall annually, of which 1,857 BCM (88%) returns to the atmosphere through evapotranspiration, leaving approximately 252 BCM as renewable water resources. These resources were partitioned among basin outflow (12 BCM), contribution to subsurface system (66 BCM), and retained open water (174 BCM). Basin-wide blue-water demand in 2020 totaled 90 BCM, of which 69 BCM was used for irrigation and the remaining 21 BCM for domestic and industrial uses. By integrating water availability, infrastructure, and demand across the entire basin, this study establishes a consistent contemporary baseline for evaluating water-resource availability, assessing supply–demand dynamics, and supporting future climatic and socioeconomic analyses.