Modeling integrated impacts of agro-hydrological interventions on blue and green water and crop yield in SWAT+

Lake Tana sub-basin, Ethiopia This study evaluates integrated impacts of agro-hydrological interventions on blue and green water, and crop yield using SWAT+. The model was calibrated and validated with monthly streamflow data and long-term average maize yield. Assessed interventions included soil/stone bunds, conservation tillage, early and late planting, and fertilizer applications at 100 kg/ha and 200 kg/ha, using historical climate data from 1992–2021. SWAT+ is suitable for simulating hydrology and crop yield in the study area. At areal average scale, early and late planting reduced blue water by 0.3 % while increasing green water flow (GWF) by 0.4 %. Other practices had no discernible effect on blue water or GWF. Green water storage (GWS) increased under early planting (3.3 %) and conservation tillage (0.8 %) but declined with late planting (9.1 %). Crop yield increased with early planting (12.1 %), fertilizer application at 100 kg/ha and 200 kg/ha (16.0 % and 24.5 %, respectively), and the adoption of soil/stone bunds (0.4 %). Conversely, late planting and conservation tillage reduced crop yields. Spatial analysis revealed that intervention effects varied across regions in water and crop outcomes. Certain practices like early planting, increased crop yields but also led to unintended reductions in blue water. These findings highlight the need for integrated, region-specific agro-hydrological strategies to balance agricultural productivity with sustainable water resource management. • Integrated impacts of agro-hydrological interventions on water and crop yield were evaluated using SWAT+. • The effects of interventions varied across different areas of the study sub-basin. • An intervention that increased crop yield reduced blue water. • Sustainable water and agricultural management require integrated, region-specific strategies.