Assessing the Water-Resources Potential and Soil Erosion Hotspot Areas for Sustainable Land Management in the Gidabo Watershed, Rift Valley Lake Basin of Ethiopia

Abstract

For development of a comprehensive sediment management plan, it is crucial to categorize watersheds on the basis of soil erosion hotspot areas to extend the useful life of water bodies (e.g., Gidam reservoir). The goal of this study was to assess the surface water potential and identify erosion hotspot areas of the Gidabo watershed in Ethiopia using the Soil and Water Assessment Tool (SWAT) model. The SUFI-2 (Sequential Uncertainty Fitting Version 2) program was used to calibrate the model, and the model’s performance was evaluated. According to the catchment prioritization analysis, some of the sub-basins with similar land use, land cover, and soil type but with higher slope would generate higher sediment yield. Furthermore, the soil conservation scenarios were developed in SWAT, and the model result showed that average annual sediment yield could be reduced by the application of grassed waterway, filter strips, terracing, and contouring by 49%, 37.53%, 62.32%, and 54.6% respectively. It was concluded that sediment yield reduction by applying terracing was more effective than other conservation measures for affected sub-basins. The surface water potential of the watershed varies spatially from sub-basin to sub-basin, and the mean monthly surface water potential of the watershed is 33 million cubic meters. These findings can help decision-makers to develop appropriate strategies to minimize the erosion rate from erosion hotspot areas and to allocate the watershed water potential for different types of water demands. Strip planting, terracing, or contour farming may be necessary on chosen hotspot erosion sites to reduce the effect of slopes on surface runoff flow velocity and sediment transport capacity.

Spatial modeling of soil loss as a response to land use-land cover change in Didessa sub-basin, the agricultural watershed of Ethiopia

“…Though this technique has been attributed to conservation forests, reforestation is more likely to protect soil loss than agroforestry by 60%, as reported in Nampo and Hwanghaebuk-do, which are the nearest areas to Pyeongyang [ 17 ]. The same token the agricultural land soil loss from Gidabo watershed in the Rift Valley lake basin could be reduced by 63 and 49% by applying terracing and grassed waterway, respectively [ 1 ]. In our study, the spatial extent of poor open-up forest cover sustained its second position at a rate of 23%, similar to what the year 1987 could endure due to soil loss.…”

“…Soil erosion as a comprehensive land degradation problem is a very thoughtful environmental concern as it gets rid of soil-rich nutrients and the upsurge level of sedimentation in rivers, which lessens the life span of the watercourse channel. Soil erosion was amplified throughout this century and contributed to 85% of global land degradation (Moges and Bhat, 2017); [ [1] , [2] , [3] , [4] ]. Human-induced land use-land cover (LULC) change has momentous long-term effects on soil erosion.…”

Integrated Modeling of Land Degradation Dynamics and Insights on the Possible Future Management Alternatives in the Gidabo River Basin, Ethiopian Rift Valley

“…Due to the lack of continuoustime step sediment records, sediment yield data were generated using sediment rating curve (SRC). The SRC is extensively used to overcome the scarcity of temporal sediment data [45][46][47][48][49]. Hence, the suspended sediment load for Aposto and Bedessa gauging stations was generated using the sediment discharge rating curve developed by Adi et al [48] with an R 2 value of 0.96 and 0.91, respectively.…”

Soil erosion variations along land use and land cover dynamics in Matenchose watershed, Rift Valley Basin, Southern Ethiopia

“…Several researchers had examined the likelihood of soil erosion in the Ethiopian Rift Valley Basin at various temporal and spatial scales (Ayana et al, 2019; Bekele & Gemi, 2021; Dananto et al, 2022; Degife et al, 2019; Jothimani et al, 2022; Woldesenbet et al, 2020; Wolka et al, 2015; Yirgu, 2022). The magnitude and extent, on the other hand, differ from region to region based on existing farming practices, land management strategies, soil type, erosion susceptibility, and landscape characteristics.…”