Soil erosion and sediment export under rainfed agriculture dominated landscapes: Model-based evidence from the Didessa watershed, southwestern Ethiopia

Numerous studies found that the main factor contributing to the export of sediment from the Ethiopian highlands is soil erosion, which is related to the expansion of cultivated land at the expense of steep slopes of natural vegetation covers. Plantation practices on steep slopes of bare surfaces and utilizing effective water and soil conservation measures on cultivated lands, may, however, have an impact on the rate of soil loss and the sediment yield ratio. Thus, the main objective of the research was to determine how changes in land use and land cover introduced by soil conservation affected the spatiotemporal variability in soil loss and sediment delivery ratio. RUSLE, InVEST, and integrated GIS technology were used to quantify the study's results. The expansion of farmed land at the expense of natural forests, woodlands, shrubs, and grasslands between 1990 and 2000 resulted in a significant increase in soil loss and sediment yield. This was mostly seen where natural vegetation cover areas on steep slopes were turned into cultivable land. Watershed development interventions significantly decreased both the mean annual soil loss and sediment yields between 2003 and 2021. For instance, from 2010 to 2021, the mean annual soil loss in the watershed dropped by 23.5 t ha−1 and the sediment export declined by 6.13 t ha−1yr−1. To prevent soil loss and sediment export at the extensive level, it is therefore concluded that sustainable soil management on cultivated land and plantation techniques on community land should be expanded up to the adjacent watersheds.

Erosion risk assessment: A contribution for conservation priority area identification in the sub-basin of Lake Tana, north-western Ethiopia

Gullies are significant contributors to soil degradation in several regions of Brazil, including Minas Gerais, where erosion processes have caused soil loss. The characterization of erosion processes is crucial for the application of measures for recovering degraded areas and reducing erosion impacts. This study models soil loss with the use of InVEST software and assesses the impact of three different scenarios, namely (1) implementation of soil conservation practices and replacement of pasture areas for temporary agriculture, (2) reforestation of pasture areas, and (3) preservation of ciliary forests. Soil loss, sediment exportation, retention, and deposition for the present scenario (2019), as well as the three aforementioned hypothetical scenarios, were estimated. In the present scenario, the estimated mean annual soil loss was 2.75 t/ha year, with 1,449.54 t/year sediment exportation, 9,042.13 t/year retention, and 1,449.54 t/year deposition. The model predicted scenario 1 would result in 2.23 t/ha year mean annual soil loss, 1,300.59 t/year sediment exportation, 9,191.08 t/year retention, and 11,755.76 t/year deposition. Scenario 2 showed 1.92 t/ha year mean annual soil loss, 1,046.69 t/year sediment exportation, 9,444.98 t/year retention, and 10,229.77 t/year deposition, whereas the results for scenario 3 were 2.36 t/ha year, 616.65 t/year, 9,862.06 t/year, and 13,206.47 t/year, respectively. Reforestation and preservation of ciliary forests, along with soil conservation practices, were effective measures for reducing soil loss. Such findings are valuable for the management of areas degraded by erosion processes.

Water erosion is a serious and continuous environmental problem in many parts of the world. The need to quantify the amount of erosion, sediment delivery, and sediment yield in a spatially distributed form has become essential at the watershed scale and in the implementation of conservation efforts. In this study, an effort to predict potential annual soil loss and sediment yield is conducted by using the Revised Universal Soil Loss Equation (RUSLE) model with adaptation in a geographic information system (GIS). The rainfall erosivity, soil erosivity, slope length, steepness, plant cover, and management practice and conservation support practice factors are among the basic factors that are obtained from monthly and annual rainfall data, soil map of the region, 50-m digital elevation model, remote sensing (RS) techniques (with use of Normalized Difference Vegetation Index), and GIS, respectively. The Ilam dam watershed which is located southeast part of Ilam province in western Iran is considered as study area. The study indicates that the slope length and steepness of the RUSLE model are the most effective factors controlling soil erosion in the region. The mean annual soil loss and sediment yield are also predicted. Moreover, the results indicated that 45.25%, 12.18%, 12.44%, 10.79%, and 19.34% of the study area are under minimal, low, moderate, high, and extreme actual erosion risks, respectively. Since 30.13% of the region is under high and extreme erosion risk, adoption of suitable conservation measures seems to be inevitable. So, the RUSLE model integrated with RS and GIS techniques has a great potential for producing accurate and inexpensive erosion and sediment yield risk maps in Iran.

Soil loss is one of the major challenges for agricultural production in the Ethiopian highlands. The rate and distribution of soil loss (SL) and sediment export (SE) are essential to map degradation “hotspot” areas for prioritizing soil and water conservation measures. The objective of this study was to estimate the dynamics of SL and SE in the Upper Bilate River Catchment of Central Ethiopia. The Sediment Delivery Ratio (SDR) module of the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model was used to estimate and map SL and SE. The primary input data were rainfall, soil data, land use, and other biophysical parameters of the study area. The model output confirmed that the average total soil loss of the catchment was 36.8 million ton/yr. It is modeled that soil loss doubles within 30 years. The average annual sediment export was about 3.62 ton/ha/yr. The mean annual soil loss of the study area was 23 ton/ha/yr, which exceeded the soil loss tolerance (SLT), estimated to range between (2–18 ton/ha/yr) in Ethiopia. Based on the soil erosion risk level, about 22% of the catchment area was classified as severely degraded, while 62 % was moderately degraded. Severe soil erosion prevails in the sub-watershed (SW)-5, SW-4, and SW-13. Therefore, these sub-watersheds need priority conservation action to restore the ecosystem processes of the study area.

BackgroundAssessing soil erosion, sediment yield and sediment retention capacity of watersheds is one of the under-researched areas in watersheds of developing countries like Lake Hawassa watershed. The study examined soil erosion and sediment yield and their environmental implications in the Lake Hawassa watershed. The quantification and mapping were carried out using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model. Data such as Land Use Land Cover (LULC), Digital Elevation Model (DEM), rainfall, soil, and management practice were used as input parameters.ResultsThe empirical analysis confirmed that the watershed has a total soil loss of about 5.27 Mt annually. The mean annual erosion rate from the watershed was estimated to be 37 t ha−1 year−1. The estimated erosion rate was greater than the maximum tolerable erosion limit in Ethiopia (2–18 t ha−1 year−1). The total amount of sediment which was exported to the nearby streams and lakes in the watershed was estimated to be 1.6 t ha−1 year−1. The water bodies receive a total of 226,690.3 t of sediment annually. Although higher soil loss and sediment export per unit of area were estimated from the highest slope gradients, greater contributions to the total soil loss and sediment export were computed from slopes with 5–30% gradients. In terms of LULC, the highest contribution to the total soil loss was computed from cultivated land while the highest rate of soil loss per hectare was observed from bare land. Due to the existing vegetative cover, a total of 18.65 Mt (130.7 t ha−1 year−1) of sediment was retained. Vegetation-covered LULCs such as forest, woodland, shrubland, and agroforestry revealed the highest sediment retention capacity. As a result of the increased soil erosion and sediment yield in the watershed, the drying-out of a small lake and the rise in the water level of Lake Hawassa were identified.ConclusionMost of the soil loss and sediment yield were contributed by a small part of the watershed. Thus, the results underscore the urgent need for targeted soil and water conservation measures of various types to ensure the sustainability of the watershed resources.

Use of a 137Cs re-sampling technique to investigate temporal changes in soil erosion and sediment mobilisation for a small forested catchment in southern Italy

Soil erosion risk and sediment yield assessment with Revised Universal Soil Loss Equation and GIS: The case of Nesha watershed, Southwestern Ethiopia

GIS-based assessment of soil erosion and sediment yield using the revised universal soil loss equation (RUSLE) model in the Murredu Watershed, Telangana, India

Modeling the impact of land use land cover change on the estimation of soil loss and sediment export using InVEST model at the Rib watershed of Upper Blue Nile Basin, Ethiopia

Evaluating InVEST model for estimating soil loss and sediment export in data scarce regions of the Abbay (Upper Blue Nile) Basin: Implications for land managers

Soil erosion accelerated by human activities is a critical challenge affecting soil health, agricultural productivity, food security and environmental sustainability in the highlands of Ethiopia. The aim of this study was to examine the dynamics of soil loss and sediment yield potential, and identify soil erosion hotspots using RUSLE with GIS in the Suha watershed, north western highlands of Ethiopia. Digital Elevation Model, LU/LC, rainfall, soil, and conservation practice were used as input data for RUSLE model. The estimated total annual soil loss for the entire watershed increased from 1.22 million tons in 1985 to 2.43 million tons in 2019, with average annual soil loss rates of 15.2 t ha−1 yr−1 and 31.4 t ha−1 yr−1 respectively. Total sediment yield also increased from 317.52 to 630.85 thousand tons over the past 35 years. In addition, the area of soil erosion hotspots changed from 15.2% (12,708 ha) to 32% (25,660 ha) during the same periods. Sub watershed 1, 2, 15, 17, 18, and 23 are severely degraded parts of the watershed. Expansion of agriculture and bare land as the expenses of other land use types over the past 35 years could be the major causes of extensive soil erosion risk in the watershed. Besides its temporal variability, soil loss and sediment export also showed variation between land use/cover classes. The estimated results of soil loss and sediment yield as well as soil erosion hotspots revealed that the soil erosion risk is progressively increasing during the study periods. Unless action is taken and the current condition is reversed, it will critically threat the livelihoods of the community in the watershed. Generally, the results underscore urgent demand for integrated and effective watershed management strategies.

Soil is one of the most important natural resources on Earth. Information on soil loss is important to support agricultural productivity and natural resource management. Therefore, this research aimed to estimate and map mean annual soil erosion and sediment deposition using a geographic information system (GIS). The soil loss in each grid cell was analysed by the revised universal soil loss equation (RUSLE) model. The parameters of the RUSLE including rainfall, soil type, and land use were calculated in each grid cell from a digital elevation model with of 1‐km2 resolution. Furthermore, sediment deposition was derived from the RUSLE model and used in GIS software to generate soil loss capacity maps. The results show that soil erosion occurred over all parts of Thailand, especially in the northern and southern parts due to the topography, geology, and land cover. The sediment was deposited in grid cells where the elevation was low, primarily near rivers. The results of this research support local land development policies that are implemented to control sediment yields during development.

Soil loss due to surface runoff is a natural phenomenon accelerated by anthropogenic activities. The study attempted to evaluate soil loss, sediment export, and deposition as influenced by changes in land use and land cover (LULC) in the Bontanga watershed. The InVEST-SDR model integrated with RUSLE was used in soil loss assessment. Results revealed that agricultural land produced 11,365.39 tons/year of soil loss in 1997, followed by 17,476.85 tons/year in 2002. In 2013, agricultural land experienced a soil loss of 5,391.98 tons/year, which finally increased to 91,274.53 tons/year in 2022. Agricultural land exported 56.16% of sediment, 13.39% of dense forest, and 13.30% of grassland. Dense forest deposited 41.54% of the sediment load, 30.49% of mixed shrub and grassland, and 10.85% of grassland. Over a long period, agricultural land is anticipated to contribute soil loss of 2,347,414.04 tons/year and sediment export of 388,497.56 tons/year. Sediment deposition amounting to 1,048,258.78 tons/year is anticipated to be deposited within the agricultural field. Both MAE and MAPE statistical measurements indicate a good model prediction performance for soil loss and sediment export. Understanding where sediments are produced and delivered will guide decision-makers, land use planners, and watershed managers in monitoring and planning the Bontanga watershed.

Soil erosion assessment in mountainous regions is complex due to rugged topography, dynamic land use, and climate interactions. The revised universal soil loss equation (RUSLE) is widely used for regional soil erosion estimation, but it often overestimates soil loss in such landscapes. This study, conducted in the Balganga watershed of Tehri Garhwal, Uttarakhand, integrates the Integrated Valuation of Ecosystem Services and Tradeoffs-Sediment Delivery Ratio (InVEST-SDR) model to provide a more refined estimation of annual soil erosion, sediment export, and retention. Field-based soil sampling was carried out across 21 physiographic units, followed by targeted laboratory analysis. The InVEST-SDR model was applied in two stages: (1) estimating soil erosion using RUSLE and (2) computing the sediment delivery ratio to determine sediment export and retention. The results indicate that potential annual soil loss in the watershed ranges from 0 to 67.63 t ha-1yr-1, with an average of 16 . The average sediment export was 1.52 t ha-1yr-1 (range: 0 to 10.5 t ha-1yr-1), while sediment retention averaged 22.68 t ha-1yr-1, reaching up to 60 t ha-1yr-1. To validate the model, the Fallout Radionuclide (FRN) 137Cs method was employed to estimate observed soil loss across major land use/land cover (LULC) classes. A moderate correlation (R² = 0.51) was found between observed and modeled soil loss values, with a Mean Absolute Error (MAE) of 3.593, indicating reasonable predictive accuracy. The erosion assessment revealed that 58.11% of the watershed falls under the very low erosion class, while scrublands (35.51 t ha-1yr-1) and agricultural lands (16.68 t ha-1yr-1) on steep slopes exhibited the highest erosion rates. Scrublands also had the highest sediment export (3.52 t ha-1yr-1), followed by agricultural lands (2.29 t ha-1yr-1). Conversely, wellmanaged valley agricultural lands demonstrated significant sediment retention (25.84 t ha-1yr-1) from upstream sources. The study highlights vegetation cover, conservation practices, and soil erodibility (K-factor) as critical factors influencing erosion patterns. These findings reinforce the importance of integrating empirical and modeling approaches for improved erosion assessment and sustainable watershed management in fragile mountainous regions.