Ecohydrological Responses and Ecosystem Service Benefits of the Green Legacy Initiative in the Ethiopian Rift Valley Lakes Basin: A Proxy‐Based Evaluation

ABSTRACT Ethiopia's Green Legacy Initiative (GLI) is one of Africa's most ambitious large‐scale Nature‐based Solutions. This study applied the Multiscale Hydrologic Ecosystem Services Proxy (MS‐HES Proxy) Framework to evaluate the ecohydrological impacts of GLI across multiple spatial scales—from basin to plot level—within the Rift Valley Lakes Basin (RVLB). The approach integrated key indicators as proxies for ecosystem services: basin‐scale Normalized Difference Vegetation Index (NDVI) for vegetation greenness, subbasin‐scale curve number (CN) analysis for hydrological regulation and plot‐scale Landscape Functionality Analysis (LFA) combined with the Shannon–Wiener Index to assess soil functionality, nutrient cycling and biodiversity. Results showed notable improvements across scales. NDVI increased from 0.48 to 0.53, indicating enhanced vegetation cover, whereas CN declined from 82.62 to 81.60, reflecting reduced runoff and improved flood regulation. At the field scale, soil stability rose from 35% (control) to 50% under GLI and 77.5% with soil and water conservation (SWC); infiltration nearly tripled (16.9% to 65%–68.9%); and nutrient cycling improved from 9%–14% to 46%–69%, reaching 100% under GLI + SWC. Biodiversity (H′) increased from 0.77 to 1.75 under GLI + SWC, peaking at 2.26. The results demonstrate a clear ecosystem‐service pathway: restoring soil stability and hydrological function enhances regulating and supporting services, which in turn strengthen provisioning and cultural benefits. Overall, the study signifies a shift from tree planting towards multifunctional ecosystem restoration. Strengthening community‐based watershed stewardship and long‐term ecosystem management is essential to sustain GLI's ecological and socioeconomic benefits.