Land cover change and its implication to hydrological regimes and soil erosion in Awash River basin, Ethiopia: a systematic review

The Awash River basin is one of the most developed basins in Ethiopia, and its water resources are crucial to development. The collective impact of land cover (LC) changes has driven a difference in the hydrological components, substantially impacting the availability of water resources and demand. This review aimed (i) to examine the extent of change quantitatively and its effects; (ii) to analyze the relationship with a mean annual rainfall that would further reveal the causes and potential LC type response to hydrologic variables in the Awash River basin, Ethiopia. The results have revealed that urbanization and agricultural activities in the basin are the most trending types of LC, while the forest, shrubland, grassland, and pasture land have been decreasing significantly in the subbasins. As a result, the change in these subbasins has triggered hydrologic variations (runoff, groundwater flow, base flow, and evapotranspiration), and its impacts on downstream basins have mostly been flood and drought. In addition, farmland, urbanization, and shrubland trends showed a significant positive interaction, while forest and water bodies had a substantial and slight negative relation to mean annual rainfall, respectively. Vegetation, bareland, urbanization, and agriculture/farmland are directly responsible for the hydrologic variation. LC change significantly affected hydrologic regimes and the distribution of spatial rainfall is correlated significantly to LC change pattern. Besides, due to the lack of LC management practices, the impact continues to propagate. Hence, this review helps to portray the potential implications and extent of effects of changes in LC on the hydrological regimes. As a result, the implementation of sound water management strategies and practices in response to changing environments to resurrect water scarcity and mitigate flood and sediment are needed straightaway.