Soil Loss Estimation for Conservation Planning in the Welmel Watershed of the Genale Dawa Basin, Ethiopia

Abstract

As a form of environmental degradation, soil degradation directly or indirectly affects many lives through decreased agricultural yields, increased flooding and habitat loss. Soil loss has been increasing in most parts of the world and is most pronounced in tropical developing countries where there is poor or zero soil and water conservation (SWC) planning and management activities. Identifying areas prone to soil erosion has also been inadequate, having not been informed by dedicated scientific studies. This is true of the poorly understood watershed of Welmel in the Oromia region of Ethiopia, where most livelihoods heavily rely upon agriculture. To plan effective SWC management techniques, a solid knowledge of spatial variations across different climate, land use and soil erosion is essential. This study has aimed at identifying potential areas needing SWC practices through conducting a spatial modeling of soil erosion within the Welmel watershed’s Genale Dawa basin using a geographic information system (GIS), remote sensing (RS), multiple factors as land uses and climate. The Welmel catchment is located in southeastern Ethiopia and extends between 5°0′0″ N–7°45′00″ N and 39°0′0″ E–41°15′0″ E. The revised universal soil loss equation (RUSLE), which was previously adapted to Ethiopian conditions, was used to estimate potential soil loss. It used information on interpolated rainfall erosivity (R), soil erodibility (K), vegetation cover (C) and topography (LS) from a digital elevation model (DEM) and that of conservation practices (P) from satellite images. The study demonstrates that the RUSLE using GIS and RS considering different climates and land management practices provides a great advantage in that it allows one to spatially analyze multilayer data in order to identify soil erosion-prone areas and thereby develop the most appropriate watershed management strategy. The mean soil loss was determined to be 31 tons ha−1 year−1 and it varied between 0 and 169 tons ha−1 year−1. About 79% of the watershed lies within the tolerable level of 11 tons ha−1 year−1. However, the remaining 21% has a high soil truncation trait, mainly due to its steeper slope and use as cultivated land. Our study identifies cultivated and deforested areas of the watershed as the potential SWC practice demanding areas. Thus, the application of RUSEL using GIS across different land management practices and climate zones is a potential tool for identifying SWC demanding sites. This remains helpful in efforts towards sustainable land management practices for the sustainable livelihood of the local human population.

Soil erosion and sediment yield assessment using RUSLE and GIS-based approach in Anjeb watershed, Northwest Ethiopia

“…Further, the cultivated lands were categorized according to slope classes, since management practices are depending on slopes. The LULC and slope raster layers of the watershed were overlaid in ArcGIS to create a layer of agricultural fields with varying slope classes, and P-factor was allocated for the corresponding slope class [42,73,74] (Table 6, Fig. 5a).…”

Modeling soil erosion susceptibility and LULC dynamics for land degradation management using geoinformation technology in Debre Tabor district, Northwestern highlands of Ethiopia

“…Modeling soil erosion is the procedure of statistically recitation soil element detachment, transportation, and confession on terrestrial surfaces and it can be castoff as extrapolative apparatuses for evaluating soil erosion aimed at management preparation, soil loss records when soil erosion is happening, and for sympathetic erosion processes (Marques et al, 2007;Tessema et al, 2020). Sophisticated and properly standardized models provide good estimations of soil erosion risks.…”

“…Soil erosion is one of the greatest severe types of land degradation, in which it affects agricultural productivity, food security, and the national economy of the country (Mhiret et al, 2019;Thapa, 2020). Accelerated erosion due to anthropogenic factors at a global scale was causing reservoir sedimentation, river morphology changes, and river bed siltation (Hailu, 2017;Tessema et al, 2020), and it had been a chronic problem ever since the beginning of settled agriculture and remained the same in the 21st century, especially in developing countries like Ethiopia (Megersa, 2014).…”

“…The loss of soil in Debre Tabor district from cultivated land can prime to a decrease in crop yield manufacture potential, degrade drainage networks, and minor surface water quality ( Hailu, 2017;May et al, 2005). Debre Tabor district, some area gets a high amount of rainfall on an arable steep slope that causes high runoff generation (Molla and Sisheber, 2017;Tessema et al, 2020). By way of a consequence, soil wearing away is a serious problem in the area.…”

Soil Loss Estimation for Conservation Planning in The Dolago Watershed Central Sulawesi, Indonesia

“…Prediction of soil loss and critical land identification for the application of forest and land management in watersheds are the core of the soil and water conservation program [Tesfaye et al, 2018]. RUSLE has been adopted in several countries in the world as an equation of soil loss giving the best results in planning soil and water conservation in a sustainable manner [Kalambukattu and Kumar, 2017; Tessema et al, 2020]. According to Phinzi et al, (2021), RUSLE is an equation that is useful as a guide in the soil and water conservation strategies, both mechanically and vegetatively.…”