Soil Erosion Risk Research Articles

Towards a better understanding of pathways of multiple co-occurring erosion processes on global cropland

Soil erosion is a complex process involving multiple natural and anthropic agents, causing the deterioration of multiple components comprising soil health. Here, we provide an estimate of the spatial patterns of cropland susceptibility to erosion by sheet and rill, gully, wind, tillage, and root crops harvesting and report the co-occurrence of these processes using a multi-model approach. In addition, to give a global overview of potential future changes, we identify the locations where these multiple concurrent soil erosion processes may be expected to intersect with projected dry/wet climate changes by 2070. Of a modelled 1.48 billion hectares (B ha) of global cropland, our results indicate that 0.56 B ha (∼36% of the total area) are highly susceptible (classes 4 and 5) to a single erosion process, 0.27 B ha (∼18% of the total area) to two processes and 0.02 B ha (1.4% of the total area) to three or more processes. An estimated 0.82 B ha of croplands are susceptible to possible increases in water (0.68 B ha) and wind (0.14 B ha) erosion. We contend that the presented set of estimates represents a basis for enhancing our foundational knowledge on the geography of soil erosion at the global scale. The generated insight on multiple erosion processes can be a useful starting point for decision-makers working with ex-post and ex-ante policy evaluation of the UN Sustainable Development Goal 15 (Life on Land) activities. Scientifically, this work provides the hitherto most comprehensive assessment of soil erosion risks at the global scale, based on state-of-the-art models.

Soil erosion risk assessment using geospatial technologies and RUSLE model in Bore Guda Watershed, Southwestern Ethiopia

ABSTRACT Soil loss is one of the critical environmental problems caused by poor land use system, especially in developing countries. The loss of top soil through erosion in developing countries leads to loss of fertile soil which in turn increases the problem of food security. This study used the integration of the revised universal soil loss equation (RUSLE) model and geospatial techniques to assess the annual soil loss at Bore Guda watershed of Gibe River basin in southwestern parts of Ethiopia. To calculate the annual soil loss five factors, namely, rainfall erosivity, soil erodibility, topographic, cover management, and conservation practices were considered. The final soil loss severity classes were categorized into low, moderate, high, very high, and severe. The findings of the study revealed that the annual soil loss in the study area ranges from 0 to 775.784 ton/ha/year with average annual soil loss of 54.68 ton/ha/year. The results clearly showed that about 199.05 km2 (9.2%) and 872.63 km2 (41.29%) of the study area were identified as very high and severe soil loss, respectively. The results clearly showed that substantial areas categorized under severe erosion severity classes. Agricultural intensification caused by rapid population growth and high demand for more food is aggravating the problem of soil erosion. The increasing conversion due to agricultural intensification played a significant role in soil loss. The results of the study support decision makers, land administration, environmentalists, and others about the urgency of the situation and how to manage landscapes to minimize the severity of soil loss.

Potential risk of soil erosion on the Tibetan Plateau during 1990–2020: Impact of climate change and human activities

With global warming and increasing anthropogenic activities, the ecosystems on the Tibetan Plateau are becoming increasingly fragile, exacerbating the risk of soil erosion in the area. However, the interacting effects induced by numerous erosion processes occurring at different times and spaces on the Tibetan Plateau are challenging to quantify using the conventional single-process assessment models (e.g., water erosion, wind erosion, and freeze–thaw). Consequently, our understanding of the complicated state of the plateau with respect to the potential for soil erosion is limited. Therefore, we created a methodological framework using multi-criteria decision-making (MCDM) to evaluate the potential risk of various soil erosion processes driven by climate change and human activity under current soil and topographical circumstances in this region. The results showed that the assessment model was reliable, and the estimated accuracy using the receiver operating characteristic curve for the training and validation datasets was 0.721. The majority of the areas of the plateau (60.69%) were at very-low or low-risk levels, while 17.55% of the plateau (mainly in the southeast and along the surrounding high mountains) was at high risk. In general, the average potential risk of soil erosion significantly increased during 1990–2020, and climate change exerted more pressure on the land surface than human activities did. The potential risk increased dramatically in 28.15% of the total plateau area, and was found to be concentrated in the plateau’s southern, eastern, central, and northern regions. The findings of this study provide a basis for local ecological environmental protection and land resource management on the Tibetan Plateau and propose a new protocol to forecast and prevent soil erosion worldwide.

Agricultural Practices and Soil and Water Conservation in the Transboundary Region of Kenya and Uganda: Farmers’ Perspectives of Current Soil Erosion

Poor agricultural practices among small-scale sub-Saharan African farmers can lead to soil erosion and reduce agricultural productivity. However, information on such practices is normally not well documented, making it challenging to design future mitigation strategies. We conducted a fine-scale agricultural survey on 200 farm households within the transboundary Sio Malaba Malakisi River Basin (SMMRB) between Kenya and Uganda to quantify the frequency and type of soil conservation practices (SWCPs) implemented. Information on farm sizes, ownership, crops grown, soil fertility, soil erosion, soil water conservation practices, and the decision-making processes was collected. Descriptive and chi-squared statistics were used to present trends in land use, decision-making processes and the extent of adoption of SWCPs, as well as to analyse the relationship between the SWCPs and the farmers’ perceptions on soil erosion. The region showed highly fragmented farms (mean area: 0.6 ha), primarily practising rain-fed subsistence farming. The principal decision-makers of each farm were mainly (63%) male. Various farmers (28%) lacked soil and water conservation practices (SWCPs). However, most farmers (35%) implemented one type of soil and water conservation practice, while 37% practised a combination of two to five soil and water conservation practices. Extensive soil and water conservation practices such as intercropping were widely practised as they were more affordable than intensive measures. Results on the farmers’ perceptions on soil erosion showed that most farmers in the SMMRB reported soil erosion (60%) and even more (92%) reported to have experienced a loss of soil fertility over the last 5 years. There was a significant positive correlation (X2 (2, n = 198) = 92.8, p = < 0.001) between the perception of soil erosion and the perception of the change in soil fertility, suggesting that reducing soil erosion could result in a reduction in the loss of soil fertility. Thus, there is still a need for strategies and measures to address the soil erosion risks currently faced by Sio Malaba Malakisi River Basin farmers. This study is a baseline study that shows the importance of farmers’ perceptions on the practice of soil and water conservation measures in the Sio Malaba Malakisi River Basin and therefore becomes an important avenue for improving the currently practised soil and water conservation measures as well as developing adoption programs as well as future studies that combine scientific and farmers’ perception/knowledge for sustainable agriculture. Further research into the efficiency of currently adopted SWCPs as well as the extent of the farmers’ knowledge and the accuracy of their perceptions is recommended.

Assessment of Integrated Soil and Water Conservation Practices on Soil Erosion Risk in a Typical Red-Beds Watershed in South China

Soil erosion is the primary factor inducing soil deterioration in large river basins. Management and conservation of the soil erosion of the red bed desert, a unique gully landform shaped by intensive weathering and hydraulic erosion under the humid climate in south-eastern China, is crucial for its long-term sustainable development. This study, focusing on the Nanxiong Basin, a representative area with red beds, applied Gaofen(Gf)-2 satellite images to the RUSLE Model to analyze soil erosion modulus before and after implementing treatment for soil erosion control. We qualified the volume of soil erosion and mapped the spatial erosion variability in the basin. The results exhibited a decrease in the average erosion modulus from 3943.56 t·km−2·yr−1 to 2023.1 t·km−2·yr−1, which caused a reduction in total soil loss from 4.64 million tons to 2.38 million tons after treatment, with a reduction of about 48.7%. The mitigation reduced soil erosion from a moderate level to a light level. The areas that integrated soil and water conservation practices (SWCP) with management measures showed evident improvement in soil erosion, with a dramatic reduction in areas with annual erosion of a strong level (5000~8000 t·km−2·yr−1), extremely strong level (8000~15,000 t·km−2·yr−1), and severe level (>15,000 t·km−2·yr−1). Despite spatial heterogeneity in soil erosion intensity in the basin, this study demonstrates the great performance of SWCP in mitigating red bed degradation. The study provides a solid scientific basis for soil erosion control using ecological engineering in the Nanxiong Basin. It can also serve as an illustrative case study for further applications on soil erosion assessment in similar small basins.

Characteristics and Projection of Rainfall Erosivity Distribution in the Hengduan Mountains

This study examines the spatiotemporal variations of rainfall erosivity in the Hengduan Mountains, known for their rugged terrain and high potential for soil erosion risks, over the past 30 years. Additionally, it investigates the changing trends of rainfall erosivity between 2025 and 2040 under the Sustainable Development Pathway 2–4.5 (SSP2–4.5), using four Global Climate Models (GCMs) based on the Coupled Model Intercomparison Project phase 6 (CMIP6). The results indicate: (1) The annual distribution of rainfall erosivity in the Hengduan Mountains exhibited significant seasonal variations, ranking in the order of summer > autumn > spring > winter on a seasonal scale. (2) Over the past 30 years, there has been a slight decrease in annual precipitation and a corresponding slight increase in rainfall erosivity. Periodic extreme values occur every 6–8 years. (3) Spatially, rainfall erosivity demonstrates a decreasing gradient from southeast to northwest. There is a significant positive correlation between rainfall erosivity and precipitation, while a significant negative correlation exists with elevation in the vertical direction. Furthermore, the northeastern part of the Hengduan Mountains exhibits an increasing trend of rainfall erosivity, while the southern region experiences a decreasing trend. (4) Considering the joint driving forces of increased precipitation and erosive rainfall events, rainfall erosivity is expected to significantly increase in the future, posing a more severe risk of soil erosion in this region.

Estimation of soil erosion using the Revised Universal Soil Loss Equation (RUSLE) in Relation to Landslides in Mid-hills of Nepal

An attempt has been made in this research to assess soil erosion and its spatial distribution by the revised universal soil loss equation (RUSLE) model at Rangun Khola Watershed, western Nepal. The erosion factors were acquired from multiple sources (Satellite images, ALOSPALSAR DEM, SOTER soil database, Esri 2020 land cover map, rainfall database of DHM) and an integrated analysis was carried out in raster format of GIS. A landslide inventory was generated on the basis of satellite images and past literature to validate soil erosion intensity in the area. The result map of the RUSLE model was categorized into six levels based on the erosion severity, and 9.06 % of the area was found to be under extremely severe soil erosion risk (> 80 ton ha”1year”1) indicating urgent consequences. The frequency ratios for each level of potential erosion susceptible to landside exhibited a linear relationship depicting reasonable and satisfactory level of agreement between the landslide event/location data and the erosion map that validates the model result. The result of this study will be helpful to detect the sensitive zones presenting a priority of protection and offer valuable information that aids decision-makers and user agencies in creating adequate conservation planning programs to stop soil erosion and maintain the natural balance.

Distribution Characteristics of Rainfall Erosivity in Jiangsu Coastal Areas

The issue of regional soil and water loss caused by human activity is particularly severe in coastal regions. Since coastal reclamation areas are a valuable land reserve resource, it is of practical significance to understand the distribution characteristics of rainfall erosion and its impact on soil erosion for the prediction, evaluation, and management of regional soil and water resources. Rainfall erosivity should be updated and estimated from simplified indices. This paper analyzed the observed rainfall data of field runoff plots in Dongtai City, Jiangsu Province, between 2011 and 2017. According to the standard of erosive rainfall in coastal areas, reporting 10.8 mm of rainfall or 7.6 mm·h−1 of I30 (maximum 30 min rainfall intensity), the annual average erosive rainfall frequency in Dongtai City was 37.7 and the annual erosive rainfall was 1082.0 mm on average, which accounted for 51.6% and 90.6% of the total rainfall frequency and the total rainfall, respectively. Moreover, the annual average rainfall erosivity in the region from 2011 to 2017 was 7717.4 MJ·mm·hm−2·h−1. The annual distribution of rainfall erosivity was irregular, with an average monthly erosivity value of 4501.8 MJ·mm·hm−2·h−1. Since the accumulated rainfall erosivity of Dongtai City in the flood season (May to September) accounted for 88.1% of the total rainfall erosivity, it is essential to focus on preventing soil and water loss in the flood season. This paper established a rainfall-based model and a composite model and intensity appropriate for a single event and monthly rainfall erosivity in the region. Both models can be used to calculate the annual rainfall erosivity, but only the composite model based on rainfall amount and intensity is recommended for calculating single and monthly rainfall erosivity levels in Jiangsu coastal areas. The empirical formulas in Jiangsu coastal areas can be updated using more recent rainfall data and assess soil erosion risk accurately.

Estimation of rainfall erosivity on the Chinese Loess Plateau: A new combination of the ERA5 dataset and machine learning

Determining the characteristics of rainfall erosivity at different times and locations is significant for global and regional soil erosion prevention and control. However, accurate quantification of rainfall erosivity remains a challenge due to the limitations of high-precision and long-time series precipitation data. Here, compared with the rainfall erosivity of 291 meteorological stations on the Chinese Loess Plateau, we evaluated the distribution characteristics and accuracy of rainfall erosivity on different temporal and spatial scales calculated by the ERA5 precipitation dataset. A random forest model was constructed to generate a bias dataset to correct the annual rainfall erosivity. Besides, the relationship between erosivity density (ED) and rainfall patterns was quantified to clarify the characteristics of rainfall erosivity. Conducted analysis suggested that the rainfall erosivity calculated from the ERA5 precipitation dataset has high accuracy on average annual, seasonal and monthly scales, and the R2 were 0.62, 0.86, and 0.85, respectively. The addition of the random forest model further optimized the result of average annual rainfall erosivity of ERA5, with root mean square error (RMSE) and absolute value of relative bias (BIAS) decreasing to 185.7 MJ mm ha−1h−1 a−1 and 2.17%, respectively. Meanwhile, ERA5 can well capture the average annual rainfall erosivity in different spaces of the study area. The high correlation between erosivity density and rainstorms (R2 = 0.87) indicated that a larger proportion of rainstorms in erosive rainfall will lead to a greater potential risk of soil erosion. These findings provide a reliable approach to accurately obtain the variable rainfall erosivity in areas with complex terrain and sparse stations, and have important implications for soil sustainability.

Modelling and mapping of soil erosion risk based on GIS and PAP/RAC guidelines in the watershed of Tassaoute (Central High-Atlas, Morocco)

Morocco watersheds, which provided many ecosystem services necessary for the socio-economic life of rural communities, are experiencing significant change and environmental problems. Therefore, examining potential soil erosion considered a major problem in the Moroccan highlands is very important to prioritize high erosion severity areas. Keeping in view of the above aspects, the present study aimed to evaluate and map areas at risk of water erosion in the upstream Tassaoute watershed (central High Atlas, Morocco), using the Priority Action Program/Regional Activity Center (PAP/RAC) method associated with Geographic Information Systems (GIS) and remote sensing. The PAP/RAC approach consisted of integrating the natural factors that influence water erosion, namely slope, lithology, vegetation cover and land use. This method provided an accurate cartographic product that reflects the reality of the state of soil degradation and the qualitative assessment of erosion. The generated erosion risk map of the study area showed that the phenomenon of erosion threatens this basin, especially in the middle and downstream, such that 40% of the basin surface has significant erosion and the high and very high degree of erosion represented 27% of the total surface of the study area. These results therefore demonstrated the PAP/CAR model reliability in assessing and mapping of water erosion risks in the upstream Tassaoute basin.

Analysis of the Asymmetric Characteristic of Extreme Rainfall Erosivity in 8 Provinces of Southern China during 1961–2020

The roles of rainfall with various intensities in hydraulic erosion processes are obviously different. In-depth knowledge about the spatiotemporal variation in extreme rainfall erosivity is critical for soil erosion risk assessment and formulation of response measures. In the period of 1961–2020, more than 390,000 erosive rainfall data from 212 meteorological stations were collected to explore the erosion characteristics of different intensities of rainfall erosivity across southern China. The asymmetric characteristic of extreme rainfall erosion was analyzed and expressed by an asymmetric change index (ACI) defined in this study. Correlation analysis was applied to study the impact of global extreme climate events on the ACI. The results showed that different patterns of precipitation had evident asymmetric characteristics in rainfall erosivity, and fewer high-intensity precipitation events contributed to much higher total rainfall erosivity, particularly for rainstorms (≥100 mm). The ACI of the rainfall erosivity exhibited evident spatial heterogeneity; insignificant increasing trends were found in the ACIs for heavy rainfall, torrential, and rainstorm erosivities over the past 60 years. The change rate of ACI varied greatly on both monthly and interdecadal scales, and the ACI of rainstorms showed the maximum linear increasing trend on the long-time scale. There were significantly high correlations between the ACI and erosive rainfall days and the ACI and erosive rainfall (p < 0.01), and the correlation coefficients were relatively higher from May to October, where the precipitation was concentrated. Additionally, the El Niño-Southern Oscillation and tropical cyclones clearly influenced the spatiotemporal distribution of the ACI and rainfall erosivity but were limited to specific periods and regions. These results could provide a reference for extreme soil erosion event monitoring and control in southern China.

Water Erosion Risk Assessment for Conservation Planning in the East Hararghe Zone, Ethiopia

Water erosion is accelerating soil loss rates in the East Hararghe Zone due to inappropriate human activities and their complex and intertwined interactions with natural factors, particularly in sensitive agroecosystems that lack soil and water conservation (SWC) measures. Although these dynamic processes cause prolonged impacts, a comprehensive assessment of the risk of soil erosion has not yet been undertaken at the zonal level. To bridge this gap, we employed the revised universal soil loss equation (RUSLE) prediction model, along with remote sensing and geographic information systems (GIS), to estimate annual soil erosion rates, analyze the temporal-spatial patterns of erosion risk, and evaluate the potential of standard conservation practices to reduce soil loss in croplands. Total soil erosion (in millions of tonnes/year; Mt yr−1) was estimated to be 9 in 1990, 14 in 2000, 12 in 2010, and 11 in 2020, with average rates of 33, 50, 44, and 39 t ha−1 yr−1, respectively. This suggests an overall 18% increase in soil erosion from 1990 to 2020. Over 75% of the area showed a tolerable soil loss rate (<10 t ha−1 yr−1) and low susceptibility to erosion risk. A mountainous landscape in the northwest presents extremely high erosion (>120 t ha−1 yr−1), which accounts for more than 80% of soil loss, making SWC planning a priority. Analysis of land-use land-cover change (LULCC) confirmed a higher increase in soil loss for LULCC that involved conversion to croplands, with average rates of 36.4 t ha−1 yr−1 (1990–2000), 70 t ha−1 yr−1 (2000–2010), and 36 t ha−1 yr−1 (2010–2020). The results have further revealed that implementing supportive practices such as terracing, stripping, and contouring could reduce average soil erosion by approximately 87%, 65%, and 29%, respectively, compared to the baseline model’s prediction. Therefore, a rigorous cost–benefit analysis is essential to design and implement optimal location-specific practices that maximize investment returns in SWC efforts and ecological restoration. However, we acknowledge the limitations of this study, associated with an empirical model that does not account for all forms of erosion, as well as reliance mainly on secondary data, which may affect the accuracy of the predicted outcomes.

Estimation of surface soil erosion using the RUSLE Model of Jalpaiguri Sadar Block in Jalpaiguri District, West Bengal, India

Land degradation is a pervasive environmental and “economic challenge of the present time, especially in developing countries. Soil erosion caused by water is considered as one of the major types of land degradation processes. Soil loss estimation and detection of soil erosion-prone areas are the most important for agricultural planning and various other land management plannings in the recent era. The amount of annual average soil loss was calculated by using the Revised Universal Soil Loss Equation (RUSLE) model. This model was popularized for identifying soil loss zone areas or zones and soil erosion risk areas. This study provided a creditable prediction of soil erosion and the probable soil erosion severity zones of Jalpaiguri Sadar Block in Jalpaiguri District, West Bengal. GIS Environment was used to create the raster layer in the RUSLE factors. RUSLE data layers including rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), cover management (C), and conservation practice (P) factors were calculated to account for the average annual soil loss of the study area. The results of this work show that the range of soil erosion is >100.00 tons hac-1year-1 to <25.00 tons hac-1year-1 while the amount of soil erosion is more in the upper part of the Jalpaiguri Sadar block, mainly along the right bank of the Tista river and the bank of the Karala river, because the soil texture is very loose in nature and the area also receive heavy rainfall. Therefore, the high level of risk of soil erosion can be checked through the processes of various soil conservation techniques.

Does helimulching after severe wildfire affect soil fungal diversity and community composition in a Mediterranean ecosystem?

Straw helimulching was applied to an area with a high soil erosion risk one month after the Navalacruz megafire (Iberian Central System, Ávila, Spain) to mitigate soil erosion and to maintain soil quality. To determine whether the soil fungal community, which is key to soil and vegetation recovery after fire, is altered by straw mulching, we examined the effect of helimulching one year after its application. Three hillside zones were chosen with two treatments in each zone (mulched and non-mulched plots), with three replicates of each treatment. Chemical and genomic DNA analyses of soil samples from mulched and non-mulched plots were performed to assess the soil characteristics and the soil fungal community composition and abundance. The total fungal operational taxonomic unit richness and abundance did not differ between treatments. However, there was an increase in the richness of litter saprotrophs, plant pathogens and wood saprotrophs associated with the application of straw mulch. The total fungal composition of mulched and non-mulched plots differed significantly. Fungal composition at the phylum level correlated with the soil potassium content and marginally with the pH and phosphorus content. The application of mulch promoted the dominance of saprotrophic functional groups. Fungal composition according to guilds was also significantly different between treatments. As conclusion, the application of mulch could mean a faster recovery of saprotrophic functional groups that will be responsible for decomposing the available dead fine fuel.

Using Dye and Bromide Tracers to Identify Preferential Water Flow in Agricultural Hillslope Soil under Controlled Conditions

Processes in hillslope soils present a particular challenge for agricultural production and soil management due to their hydropedological specifics and high soil erosion risk. Soil heterogeneities can cause preferential and/or lateral flow on the entire hillslope resulting in the off-site movement of water, fertilizers and chemicals used in crop production. A study was conducted under controlled conditions in a laboratory with undisturbed soil cores (250 cm3), which were used to estimate the soil hydraulic properties (SHP) using HYPROP and WP4C devices, while undisturbed soil columns (diameter = 16 cm, length = 25 cm) were used for the evaluation of preferential flow pathways using potassium bromide and Brilliant Blue. Samples were excavated in triplicate from the hilltop, backslope and footslope regions within the inter-rows of a vineyard from a critical zone observatory, SUPREHILL, in Croatia in Dystric Luvic Stagnosol. The aim of this study was to determine if the erosion-affected hillslope position affected the physical, chemical and hydraulic properties of soil and to identify water flow and possible preferential flow using dye and bromide tracers. The results of the sensor measurements and estimated SHPs were in agreement, showing a faster leaching of the irrigated rainwater in the footslope column. The tracer experiments showed variability even in the columns taken from the same position on the hillslope, which can be linked to plant roots and soil fauna activity. Altogether, the results showed a deeper loose layer at the footslope as a consequence of the soil erosion, which then resulted in higher hydraulic conductivity and the leached mass of the bromide due to better soil structure and pore connectivity. Thus, due to significant differences in the leached mass of bromide, this research should be later expanded in field experiments to reveal the impact of surface runoff, subsurface preferential and lateral flow on a larger scale.

Soil Detachment Rate of a Rainfall-Induced Landslide Soil

In recent decades, the number of rainfall-induced landslides has increased significantly in many parts of Malaysia, especially in the urbanized and hilly areas. The disturbance of hilly morphology as a result of human activities has increased the potential for erosion on man-made slopes, especially during extreme rainfall during rain events. Most hilly areas in Malaysia are covered by a thick layer of soil, which is known to have a significant impact on soil erosion. However, little is known about how soil erosion and rainfall could be the driving force behind landslide initiation, especially on stabilized slopes. Therefore, this study focuses on the soil detachment rate of landslides triggered by rainfall at different rainfall intensities. A sandbox model is used to represent real slope conditions. The relationship between the soil detachment capacity, soil properties (water content, slope, clay layers and soil compaction), hydraulic parameters (flow shear stress and stream power) and rainfall intensities (low, medium and high) was investigated. The results showed that the hydraulic parameters and the rainfall intensity are directly proportional to the detachment rate of the soil. Water content and slope show a higher soil detachment rate and a lower critical flow shear stress than other soil properties. It can be concluded that high saturation and steep slope increase the risk of soil erosion because the cohesion and friction of the soil are significantly reduced, leading to a weakening of the soil structure at the surface. The results of this study can feed into the existing analysis of slope stability and formulate the onset of a landslide triggered by rainfall, especially in eroded soils.

Spatial estimation of soil erosion risk using RUSLE model in District Swat, Eastern Hindu Kush, Pakistan

Abstract Soil erosion is a natural geomorphic process with the potential to damage fertile land. In this study, soil erosion risk is spatially estimated in District Swat by applying Revised Universal Soil Loss Equation (RUSLE). The RUSLE parameters that trigger soil erosion including rainfall erosivity, soil erodibility, topography, cover management, and support practices were derived from monthly rainfall data obtained from Pakistan Metrology Department, soil texture map from Soil Survey of Pakistan and Digital Soil Map of the World database, land use land cover extracted from SPOT 5 satellite image, whereas slope and digital terrain extracted from Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM). It was found from the analysis that out of the total reported area, 34.5% falls in the area affected by very high soil erosion. The results of spatial pattern and erosion proneness of the study region have been further classified into very low (45%), low (8.5%), moderate (7%), high (5.2%), and very high zones (34.5%). The results show that the study area requires effective mitigation strategies to curtail the precious soil. This study has the potential to assist the decision makers and planners for soil loss risk reduction.

Specific power or droplet shear stress: Which is the primary cause of soil erosion under low-pressure sprinklers?

Specific power and droplet shear stress are generally considered to be the most critical indicators of soil erosion in sprinkler irrigation, but there is controversy about which indicator has a greater impact. This creates uncertainty in the optimization design of low-pressure sprinkler irrigation systems. In this study, a commonly used low-pressure sprinkler, i.e., Nelson D3000, was used to carry out in soil box experiments, to study the effects of specific power and average droplet shear stress at the end of a spray jet on soil erosion during sprinkler irrigation under three nozzle diameters (3.97, 5.95, and 7.94 mm), two operating pressures (103 and 138 kPa), and two soil textures (loamy sand and silty loam). Overall, the larger specific power or average droplet shear stress resulted in higher initial and steady runoff rates and a shorter time until runoff occurs and stabilizes. Enlarging the specific power or average droplet shear stress could significantly increase the initial infiltration rate, sediment yield, and surface soil bulk density, but the infiltration depth prior to runoff and surface soil porosity decreased. Furthermore, the specific power was observed to have greater correlations than average droplet shear stress with the surface runoff rate, initial infiltration rate, and increase in the soil bulk density and decrease in the soil porosity after irrigation. However, it was weakly related to the infiltration depth prior to runoff and sediment yield, indicating that the specific power could more accurately reflect the soil erosion with respect to the shear stress. To minimize the risk of soil erosion, a small operating pressure (103 kPa) is recommended in the design of center pivot irrigation systems, especially for the overhang of the system with large nozzle diameters. This research can provide the technical support for soil erosion prevention under low-pressure sprinkler irrigation.

Soil erosion hazard assessment using the RUSLE model for the Taung Watershed of Ramotswa Agricultural District in Botswana

The Revised Universal Soil Loss Equation (RUSLE) model integrated with Remote Sensing (RS) and Geographical Information Systems (GIS) was positively validated to spatially assess soil erosion risk in the Taung Watershed of Ramotswa Agricultural District during the period 2000 – 2020. The estimated annual soil erosion averaged 12.04 and 12.74 t/ha/year in 2000 and 2020, respectively. The Land Use/Land Cover (LULC) and soil type were found to be key determinants of high soil erosion hazard when using RUSLE. The soil erosion assessment tools enabled prioritization of high erosion prone areas in the study area for soil conservation planning and watershed management.

Agricultural activities lead to sediment infilling of wetlandscapes in the Canadian Prairies: Assessment of soil erosion and sedimentation fluxes

Wetlandscapes are vulnerable to land conversion and sediment infilling from upland agriculture, causing them to act as sinks for sediment deposition and putting at risk their ecosystem services. Wetlandscapes in the Canadian Prairies agroecosystems are particularly susceptible to sediment infilling because of the intensification of human activities and agricultural practices. The rising risk of soil erosion in cultivated landscapes has generated a need to estimate soil redistribution rates and soil loss monitoring tools and techniques. This research examines the effects of agricultural activities on soil loss and sedimentation rates within agricultural landscapes in the Canadian Prairies. Land and atmospheric fluxes of sediment into wetlands are quantified over the past 60 years using catchment-scale tracing (137Cs) and budgeting techniques. Findings indicate that the pattern of 137Cs erosion/deposition varies along catchment toposequences, with erosion near the top of the toposequences (the average annual soil erosion rates were found to be 1.1 kg m−2 yr−1 for Manitoba and 0.3 kg m−2 yr−1 for Alberta) and deposition within the wetland ecosystem (total deposition rates were estimated at about −3.6 kg m−2 yr-1for Manitoba and −0.9 kg m−2 yr−1 for Alberta). The sediment delivery ratios were approximately 57% and 35% in Manitoba and Alberta, respectively, indicating that a noticeable amount of the mobilized sediment exits the field. These transfers from cultivated fields into wetlands reveal that wetlandscapes in Canadian Prairies are vulnerable to sediment infilling, and soil erosion control practices are needed to achieve sustainable management of agricultural landscapes.