A spatial-temporal assessment of groundwater development in response to soil erosion

Abstract

The sustainable management of water resources plays a significant role in boosting the country's economy, mainly in the agriculture sector. In many regions globally, the availability of surface water resources is limited and thus depends on the groundwater for irrigating crops. Furthermore, soil erosion is a severe problem such as worsened soil fertility, land-use disturbances, and sedimentation, especially in large-scaled river basins having complex topography. Therefore, assessment of the spatial-temporal variation of groundwater development, such as groundwater recharge (GWR) and groundwater safe yield (GWSY) and their response to topsoil erosion in large-scaled river basins, are crucial for sustainable groundwater development. This paper aims to assess the spatial-temporal dynamics of groundwater development in response to runoff–induced topsoil loss. A large-scale East African river basin such as the Omo River basin was chosen to demonstrate the proposed modeling approaches. The WetSpass-M physical-based hydrological model was used to estimate the longtime average annual GWR and runoff. The estimated spatial variation of GWR was used for the analysis of GWSY. Further, combined methods such as the RUSLE model, ArcGIS tool, and remote sensing (RS) data were used to estimate the spatial variation of annual topsoil erosion. The result showed that groundwater resources in cultivation land use in the Omo River basin have moderate to high productive aquifers (2–28 l/s), with maximum GWSY capacity ranging from 0.4 to 4 m3/day/ha. The estimated long-term average annual topsoil erosion is 12.35 t ha−1yr−1 and is comparable with the observed sediment yield of 13.24 t ha−1yr−1. The cultivation regions of the river basin receive maximum GWR and experience moderate to severe topsoil erosion, indicating that GWR has a direct response to topsoil erosion in the disturbed soil regions.