Modeling climate change impacts on blue and green water of the Kobo-Golina River in data-scarce upper Danakil basin, Ethiopia

Study region: Kobo-Golina River, Upper Danakil Basin, Ethiopia. Study focuses: It is crucial to understand the spatiotemporal distribution of blue water (BW) and green water (GW) for optimal use of water resources, especially in data -scarce regions. This study aims to evaluate the extent to which future climate is changing, and its impact on blue-green water resources in the study area. Projected changes were predicted based on the latest Coupled Model Intercomparison Project Phase 6 (CMIP6) Global Climate Models (GCMs) for three future periods (2015 - 2044, 2045 - 2075, 2076 - 2100) under two shared socio-economic pathways (SSP2 - 4.5 & SSP5 - 8.5). Compromise programming technique was employed to rank and select best performing GCMs. The multi -variable calibrated SWAT + model was forced with climate projections from the top -ranked CMIP6 GCMs ensemble to simulate projected blue water (BW) and green water (GW) in the study area. New hydrological insights for the region: Compared to the baseline period (1984 - 2014), blue water declined while green water exhibited an increasing trend in all future periods under two SSPs. It is also noted that the spatial distribution of BW and GW remains uneven in the study area. Precipitation significantly impacted BW than GW resources. This study provides valuable insights into the utilization of the recent CMIP6 Global Climate Model coupled with multi -variable calibrated SWAT + hydrological models for better simulation of Blue -Green water in data -scarce basins under changing climate.