Transboundary Nile basin dynamics: Land use change, drivers, and hydrological impacts under socioeconomic pathways

Landscape transitions in the Nile River basin will likely accelerate over the next decades due to socioeconomic developments and climate change. However, the assessments of land use/land cover (LULC) changes and their impact on the water resources over the Nile basin lacked a transboundary perspective. Here we used coupled basin-scale geospatial-hydrological models to project future LULC changes in the Nile basin and its three trib-utaries (i.e., White Nile, Blue Nile, and Atbara River), explored their drivers and projected hydrological impacts under different shared socioeconomic pathways (SSPs) during 2020-2060. Compared to 1992-2019, significant increases in the forested area (>50 x 103 km2) are expected to occur in the upstream areas of the White Nile and the Blue Nile in South Sudan and Ethiopia, with larger increases projected under higher emission scenarios. Consequently, it will likely reduce the downstream seasonal river discharge for the White and Blue Nile by up to 8.4% (SSP5) and 8.9% (SSP2), respectively. An increase of 7.4% in the Blue Nile discharge is expected during the flood season if the current urbanization/deforestation rates would prevail in the future. Large decreases (>15 x 103 km2) of unused land are expected in the Atbara River sub-catchment with increases in natural vegetation socioeconomic-related LULC types, leading to a river flow decrease of 15% during the rainy season under the SSPs. The basin-scale LULC changes are projected to decrease the Main Nile flow to Egypt by 3.6% under SSPs and increase by 2.1% if the historical trends prevail. The results highlight a close association between landscape dynamics, socioeconomic growth, and climate change over the Nile basin and suggest adaptive LULC planning and conservation measures.

Automated summary

Landscape transitions in the Nile River basin will likely accelerate due to socioeconomic developments and climate change, leading to significant changes in land use/land cover (LULC) and their impact on water resources. Using geospatial-hydrological models, this study projected future LULC changes in the Nile basin and its tributaries, identifying drivers and projected hydrological impacts under different socioeconomic pathways (SSPs). The results show increased forested areas in the upstream regions, reducing downstream river discharge, while unused land in the Atbara River sub-catchment is expected to decrease, resulting in a decrease in river flow during the rainy season. These findings emphasize the need for adaptive LULC planning and conservation measures in the Nile basin.