Climate change impact on Ethiopian alluvial groundwater

Abstract

Alluvial aquifers are valuable geological assets, and their productivity is reliant on the prevailing weather patterns. The study is aimed at investigating the climatic impact on the alluvial aquifers in two separate regions of Ethiopia: the western catchment (Gambela) and the eastern catchment (Somali). The research locations are characterized by semi-arid conditions and are particularly vulnerable to climate change effects. These effects of climate change on groundwater resources were assessed using global climate models and land cover data for two time periods: the present (2011–2040) and the future (2041–2070). The research was conducted using actual crop evapotranspiration (AETc), effective precipitation, and the De Martone Aridity Index (DMI) by using the spatial–temporal method. The technique employs a deduction grid to merge the effective precipitation and DMI for evaluating the effect of climate on groundwater giving five classes of effects, from very low to very high. The results show that all AETc, effective precipitation, and DMI vary both spatially and temporally for the coming periods. These changes were more pronounced in the western catchment (WC) than in the eastern catchment (EC). The present period’s impacts are most noticeable in the western region (near Jikawo) of WC, as well as in the northern (Shinile and Aysha) and southern (Deghabur) parts of EC. High and very high climatic effect zones will increase spatial coverage in those regions. The impact of climate change estimation was supported by empirical analysis of the potential recharge. The future potential recharge is reduced in magnitude in both catchments. The climate susceptibility study is significant for the two regions in managing precious water resources, such as groundwater.