Climate Change Impacts on Water Security in Ethiopia: A systematic Review of Hydroclimatic Trends, Resilience Strategies, and Governance in Major River Basins

This systematic review synthesizes 50 studies (2009–2025) examining climate change impacts on water security across Ethiopia's Abbay (Blue Nile), Awash, Omo-Gibe, and Rift Valley Lakes basins. Following PRISMA 2020 guidelines with dual-independent screening and thematic synthesis, we harmonized heterogeneous projections from diverse climate models and scenarios to enable robust cross-study comparison. Findings reveal a dominant mid- to end-century drying signal under high-emission pathways, driven by temperature-induced evapotranspiration exceeding precipitation changes. Projected impacts exhibit pronounced basin-specificity: Rift Valley Lakes shows groundwater recharge declines of 47–53% and water yield reductions of 48% by 2080s (RCP8.5); Awash shows mean annual flow reductions of 10–29% by 2050s. Abbay and Omo-Gibe exhibit scenario-dependence: under moderate pathways, Abbay shows potential flow increases of 10–25% by 2080s, while under high emissions water yield contracts by 22.7%. The review's central contribution is a basin-specific governance diagnosis: the gap between policy ideals and operational realities manifests as an enforcement deficit in Awash (>70% unlicensed abstractions), transboundary coordination void in Abbay, sectoral capture in Omo-Gibe, and regulatory drift in Rift Valley Lakes (