Soil Erosion Research Articles

Spatial–Temporal Evolution Pattern of Soil Erosion and Its Dominant Factors on the Loess Plateau from 2000 to 2020

Global changes have led to significant changes in soil erosion on the Loess Plateau. Soil erosion leads to the degradation of land resources and a decline in soil fertility, adversely affecting agricultural production and the socioeconomic situation. Therefore, revealing the spatiotemporal evolution patterns of soil erosion in the Loess Plateau region and investigating the influencing factors that contribute to soil erosion are crucial for its management and restoration. In this study, the RUSLE monthly model and the Geodetector model were utilized to reveal the spatiotemporal trends of soil erosion in the Loess Plateau from 2000 to 2020 and to determine the dominant influencing factors in different periods. The main results are as follows: (1) From 2000 to 2020, the soil erosion in the Loess Plateau initially weakened and then intensified, indicating that precipitation and precipitation intensity have different effects on surface soil. (2) From 2000 to 2015, the area experiencing slight and mild erosion increased. This is attributed to the increase in vegetation coverage in the Loess Plateau region, which has alleviated soil erosion in the area. (3) From 2000 to 2020, zones of severe soil erosion were mainly located in the cities of Yan’an and Yulin and their surrounding areas. The gravity center of soil erosion shifted northwestward from Yan’an City overall, indicating an improvement in the soil erosion conditions in the Yan’an area. (4) The predominant level of soil erosion across different land-use types was slight erosion, accounting for over 40%. This may be a result of forestry ecological projects that effectively reduce soil loss. (5) In slope zones of 0–5°, slight erosion accounted for the largest area proportion. As the slope increased, the area proportion of severe and extremely severe erosion also increased. This is attributed to the protective role of vegetation on soil in gentle slope areas. (6) From 2000 to 2020, vegetation was the dominant single factor influencing the spatiotemporal changes in soil erosion, while the interactions between vegetation and land use had the largest explanatory power, indicating that changes in land-use types partially affect variations in vegetation coverage. Our research findings could provide important data support for soil erosion control and eco-environment restoration in the Loess Plateau region.

Using radiotracers 137Cs and 210Pbex to document climate change in mountain areas through the estimate of soil erosion rates

Abstract. During the last few decades, a general increase in heavy rainfall events has been documented in many areas of the world. These events have caused changes in soil erosion rates and strongly affected the human activities in mountain areas by reducing the national income obtained from cultivated land. In this context, the use of fallout radiotracers can be an important tool for better understanding the consequences of climate change in these areas and proposing effective countermeasures in order to reduce soil loss. In this contribution, plot experiments carried out in southern Italy that involve the use of 137Cs and 210Pbex measurements were performed to estimate soil erosion rates during the last few decades. The overall results indicate an increase in soil erosion rates during the last 15–20 years and suggest the use of this technique to detect climate change in mountain areas.

On Disquieting Ground

This article focuses on attempts by inhabitants of the island of Samothraki, in North-Eastern Greece, to make sense of rapid soil erosion and degradation. Through the use of ethnographic vignettes, collected during my first fieldwork on the island in August of 2022, and broader ethnographic material, I show the imbrication of landscape perception with questions of collective ethics as well as the specific forms of social uncertainty which emerge from soil instability. The article highlights specific and local discursive attempts to make sense of broader processes, including weather events, as prompts used by Samothracians to think about their ways of inhabiting their own island.

Soil Loss Estimation and Community Awareness Assessment on Integrated Watershed Management: The Case of Lake Hashenge Watershed, Tigray, Ethiopia

Ethiopia is recognized as one of the most severely affected regions by soil erosion globally, posing significant threats to its national economy. This study investigates soil loss estimation and community awareness within the framework of integrated watershed management in the Lake Hashenge watershed, Tigray, Ethiopia. The mean annual rainfall and total drainage area of Lake Hashenge watershed is 988.7 mm and 129km2 respectively. Utilizing the Revised Universal Soil Loss Equation (RUSLE) model, we quantified soil erosion rates and identified critical areas prone to severe soil loss. Our findings indicate significant soil degradation, exacerbated by both natural and anthropogenic factors. The estimated soil loss yield entering Lake Hashenge in the form of sheet and rill erosion was 61.94 tons/ha/year. According to the universal soil loss factsheet, the soil loss estimated in the watershed was categorized as severe, indicating that the lake is in danger. Concurrently, we assessed community awareness and participation in soil conservation practices through surveys and interviews with a multidisciplinary team of researchers. The results reveal a moderate level of awareness and engagement, highlighting the need for enhanced educational and participatory approaches to foster sustainable watershed management. This research underscores the importance of integrating scientific soil loss assessments with community-based integrated watershed management strategies to mitigate soil erosion, protect the lake from sedimentation, and promote environmental sustainability in the region.

Empirical and Machine Learning Models for Soil Erosion Risk Assessment: A Case Study of Tsageri Municipality, Georgia

Soil erosion caused by water is one of the most common causes of land degradation worldwide. Within framework of this research soil erosion risk in Tsageri municipality, Georgia was evaluated using Revised Universal Soil Loss Equation (RUSLE) and a machine learning-based Random Forest (RF) model. Open access digital datasets and field observations collected in 2023-2024, which included visually identified erosion areas and GPS-recorded data on the presence or absence of erosion, were utilized in modeling process. Data processing and modeling conducted using ArcGIS Pro 3.0 and RStudio software. According to RUSLE results, 39.7% of the study area falls under the very low erosion risk zone, and 20.7% is in the very high risk zone. The RF model results indicated that 16.5% of the territory is under very low risk of erosion and 13.9% - very high risk. It was observed that RUSLE model tends to overestimate erosion rates on steep, forested slopes, while the RF model, by incorporating additional variables, provided more accurate prediction. These findings suggest that combining RUSLE with machine learning improves soil erosion risk assessment, particularly in complex landscapes such as in Tsageri municipality. Future researche should focus on testing additional variables to refine the modeling process further and enhance predictions. The generated digital thematic maps offer valuable insights for understanding the spatial dynamics of soil erosion within the study area, analyzing the factors driving the process and developing effective mitigation strategies.

An investigation on the effect of soil erosion on the properties of soil adjacent to a road right of way (ROW)

ABSTRACT Recently, soil erosion has been a significant and common issue along road right of way (ROW). This study was designed to identify the effect of soil erosion on the physical and chemical properties of soil across a ROW. Land use land cover (LULC) map, soil map, and field observation were adopted to ensure proper sampling. Moisture content, grain size analysis, soil texture, consistency test, organic content and matter, pH, and cation exchange capacity (CEC) were conducted on 10 representative soil samples collected from 14 km ROW. The laboratory results from moisture content, pH, and CEC revealed samples taken from the erosion fields (20.79% to 26.41%), (8.48 to 8.66), and (18.02 to 24.03) appeared to be higher than those taken from non-eroded fields (16.79% to 18.51%), (8.18 to 8.3), and (14.5 to 16.15), respectively. The organic content of the soil in the non-eroded areas was higher than that in the eroded areas. This variation in soil properties is primarily attributed to differences in LULC and soil composition. With regard to consistency properties, the soil was marked as highly erodible. Treatment of drainage structures, demarcating ROW, ROW stabilization, and awareness creation were proposed as feasible remedial measures. Finally, the soil along Sawla to Bulki ROW was identified as erodible soil as per experimental results and analysis.

An interpretable (explainable) model based on machine learning and SHAP interpretation technique for mapping wind erosion hazard.

Soil erosion by wind poses a significant threat to various regions across the globe, such as drylands in the Middle East and Iran. Wind erosion hazard maps can assist in identifying the regions of highest wind erosion risk and are a valuable tool for the mitigation of its destructive consequences. This study aims to map wind erosion hazards by developing an interpretable (explainable) model based on machine learning (ML) and Shapley additive exPlanation (SHAP) interpretation techniques. Four ML models, namely random forest (RF), support vector machine (SVM), extreme gradient boosting (XGB), and quadratic discriminant analysis (QDA) were used. Thirteen features associated with wind erosion were mapped spatially and then subjected to a multivariate adaptive regression spline (MARS) feature selection algorithm, and then, tolerance coefficient (TC) and variance inflation factor (VIF) statistical tests were used to explore multicollinearity among the variables. MARS analysis shows that eight features consisting of elevation (or DEM), soil bulk density, precipitation, aspect, slope, soil sand content, vegetation cover (or NDVI), and lithology were the most effective for wind erosion, while no collinearity existed among these variables. The ML models were used for ranking the effective features, and the research introduces the application of an interpretable ML model for the interpretation of predictive model's output. The ranking of effective features by RF-as the most typical ML model-revealed that elevation and soil bulk density were the two most important features. According to the area under the receiver operating characteristic curve (AUROC) (with a value > 90%) and precision-recall (PR) (with a value > 90%) curves, all four ML models performed with great accuracy. According to the PR curve, the SVM model performed slightly better than others, and its results revealed that 20.9%, 23%, and 16.6% of the total area in Hormozgan Province is characterized by moderate, high, and very high hazard classes to wind erosion, respectively. SHAP revealed that soil sand content and elevation are the most important variables contributing to the predictive model output. Overall, our research is one of the pioneering applications of interpretable ML models in mapping wind erosion hazards in Southern Iran. We recommend that future research should address the aspect of interpretability in order to better understand predictive model outputs.

Characterization of glomalin proteins in soil: A potential indicator of erosion intensity

Abstract In this study, in a pioneering effort, glomalin proteins were extracted and geochemically characterized from soil in Serbia. Standard chemical (dry combustion, Walkley-Black) and spectroscopic methods (fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), scanning electron microscope (SEM)) were used to gain insight into the glomalin proteins. Samples from the City of Novi Sad (Serbia) were used for characterization and comparison. The soil contained an average of 17 mg/g of glomalin, representing ≈21% of the soil organic matter. DLS zeta potential analysis and the FTIR spectra reveal two significant differences before and after glomalin extraction, indicating a relationship between sand fractions and organic matter that affects particle aggregation and erosion potential. A comparison of SEM images and DLS results reveals that the glomalin extract consists of two particle size groups (0.08–1 and 6 µm), suggesting that the extraction process isolates only a smaller fraction of proteins and less tightly bound particles, indicating that soil aggregation is influenced by both mineralogy and the characteristics of organic matter. Hence, our research raises important questions about the role of glomalin in mitigating soil degradation processes, particularly soil erosion. Our study will enhance the overall understanding of glomalin, inspire future research, and prove beneficial for the sustainable restoration of degraded lands.

Influence of global warming and human activity on mercury accumulation patterns in wetlands across the Qinghai-Tibet Plateau

Abstract Wetlands in the Qinghai-Tibet Plateau (QTP) are a unique and fragile ecosystem undergoing rapid changes. We show two unique patterns of mercury (Hg, a global pollutant) accumulation in wetland sediments. One is the ‘Surface Peak’ in monsoon-controlled regions, and the other is the ‘Subsurface Peak’ in westerly-controlled regions. The former is attributed to the combined effects of increasing anthropogenic emissions and climate-induced changes in the cryosphere and wetland hydrology in the last 100 − 150 years. The climate changes in westerly-controlled regions in the last 50 − 70 years led to a fluctuation of hydrology and an Hg peak in the sediment subsurface. The increase of legacy Hg input from soil erosion largely enhanced the Hg accumulation rate in wetlands since the 1950s, especially in the proglacial wetlands. We highlight that accelerated glacier melting and permafrost thawing caused by global warming have altered geomorphology and hydrology and affected Hg transport and accumulation in wetlands.

Novel adaptive control approach to fractal fractional order deforestation model and its impact on soil erosion.

Deforestation exerts profound ramifications on soil quality and biodiversity, thereby exerting substantial economic repercussions. The depletion of organic matter and structural integrity of soil following tree removal for agricultural purposes underscores the severity of this issue. In elucidating the soil pollution stemming from deforestation, this research employs a sophisticated five-compartment SDIFR model integrating fractal dimension and fractional order dynamics. The rigorous analysis, including the application of Picard Lindelof's fixed point theorem, establishes the existence and uniqueness of explicit solutions. Furthermore, the examination of local and global stability sheds light on the system's behavior, delineating between pollution-free equilibrium and pollution-extinct equilibrium states. To regulate system behavior, an adaptive control framework grounded in fractal fractional order is proposed, leveraging the Adams-Bashforth numerical approximation scheme for implementation. Through numerical simulations, the study underscores the pivotal role of parameters, thus substantiating the significance of the proposed model in comprehensively addressing the complexities of soil pollution induced by deforestation.

The Assessment of the Spatiotemporal Characteristics of Net Water Erosion and Its Driving Factors in the Yellow River Basin

The Yellow River Basin (YRB) is an important grain production base, and exploring the spatiotemporal heterogeneity and driving factors of soil erosion in the YRB is of great significance to the ecological environment and sustainable agricultural development. In this study, we employed the Revised Universal Soil Loss Equation (RUSLE) in conjunction with Transport-Limited Sediment Delivery (TLSD) to explore a modified RUSLE-TLSD for use assessing net water erosion. This modification was performed using sediment data, and the explanatory power of driving factors was assessed utilizing an optimal parameters-based geographical detector (OPGD). The results demonstrated that the modified RUSLE-TLSD can accurately simulate the spatiotemporal distribution of net water erosion (NSE = 0.5766; R2 = 0.6708). From 2000 to 2020, the net water erosion modulus in the YRB ranged between 1.62 and 5.33 t/(ha·a). Specifically, the net water erosion modulus decreased in the YRB and the middle reaches of the YRB (MYRB), but it increased in the upper reaches of the YRB (UYRB). The erosion occurred mainly in the Loess Plateau region, while the deposition occurred mainly in the Hetao Plain and Guanzhong Plain. The Normalized Difference Vegetation Index (NDVI) and slope emerged as significant driving factors, and their interaction explained 31.36% of YRB net water erosion. In addition, the redistribution of precipitation by vegetation and the slope weakened the impact of precipitation on the spatial pattern of net water erosion. This study provides a reference, offering insights to aid in the development of soil erosion control strategies within the YRB.

Comprehensive Assessment of Soil Erosion using USLE and Sustainable Management Strategies

Continuous soil erosion from all parts of world through water and winds have become a severe concerns for soil scientists and geologists due to its adverse effect on soil productivity, water bodies siltation and deterioration of water quality. Therefore, it becomes most important to locate erosion-prone regions of any landscape and take the best measures to solve the issues of erosion. USLE and its modified models i.e. RUSLE (Revised Universal Soil Loss Equation) versions and MUSLE (Modified Universal Soil Loss Equation) are most commonly used for estimation of soil erosion. In India, soil erosion is a major serious concern which varies in its intensity depending on the country's different agro-climatic zones. USLE as well known model for evaluating soil deterioration is used in this review to provide an understanding of its parameters and how this approach is useful in soil erosion assessment. In addition, an overview of the current situation of erosion status in India which is being altered by regional variations like climate and land uses. Literature also dictates and discusses the potential advantages of better erosion control approaches, such as increased agricultural output and long-term land sustainability and looks at what might be possible in the future if the things get managed. The study also looks at crop selection and land use systems, emphasizing how crucial it is to choose crops that are suitable for the land vulnerability to erosion in order to prevent the further deterioration. Lastly, it emphasize on a thorough explanation of the USLE's parameters which are essential for precise erosion prediction including slope factors, soil erodibility, rainfall erosivity and conservation techniques. The study summarizes the knowledge on soil erosion in India and the necessity of customized, area-specific soil conservation plans to guarantee long-term agricultural outputs and sustainable agricultural goals.

Tackling soil erosion and contamination within the SDGs framework: a case study of the Erdenet copper-molybdenum mine

AbstractMining operations in Mongolia have contributed significantly to national economic growth. However, the lack of adequate mine land rehabilitation practices has resulted in various forms of land degradation, including land cover change, soil erosion and contamination with heavy metals and metalloids. These issues have negatively affected ecosystems and posed potential risks to human health due to the interconnected relationships between land, water and human activities. This study focuses on the copper-molybdenum mining site of Erdenet, the oldest and one of the largest copper mines in Mongolia, to investigate the main drivers of soil degradation and evaluate effective rehabilitation strategies. By combining findings from our previous studies on soil erosion and contamination in the Erdenet area with a review of existing research, we assess key rehabilitation priorities. Taking a Nexus approach, this study explores the interconnections between environmental, economic and social sectors, emphasizing the importance of balancing mining activities with sustainable land management. The previous studies suggest that for the next 10–15 years, priorities should focus on tailings storage facility rehabilitation and soil contamination remediation, while longer-term goals include developing sustainable environmental management strategies that foster cooperation between mining corporations and local communities, enforce regulations and improve monitoring in the Erdenet mining area. The study aligns these priorities with the Sustainable Development Goals, offering science-based recommendations for managing soil erosion and reducing contamination.

Adoption of soil conservation practices by mandarin (Citrus reticulata B.) farmers in Gulmi, Nepal

Mandarin has a tremendous potential for export and increased income for farmers of Nepal. However, in the recent years, soil degradation and erosion are the major challenges faced by the citrus enterprises especially in the hilly region of Nepal. The declining status of production and productivity cannot be checked without the transfer of site-specific and commodity-based knowledge and skills to the corresponding farmers. A study was carried out in 2023 to examine the soil conservation practices and status of technology adoption among the mandarin farmers. A total of 80 households from three wards of Dhurkot rural municipality of Gulmi district were selected on purpose for the study. Data were collected through interviews, key informant interviews, and focus group discussion, using semi-structured questionnaire, then the descriptive analysis was done using MS Excel and SPSS (Version 23.0). The results revealed that mainly three types of soil were presented in the study areas viz. luvisols, cambisols and sandy gravel, which are highly prone to soil erosion. The average area under mandarin cultivation was reported to be 0.74 hectare, with an estimated productivity of 7.6 metric tons per hectare. Approximately 95% of the respondents were familiar with soil degradation and its consequences in mandarin production. Accordingly, 96.2% of the respondents had adopted some forms of soil conservation practices like sod culture (40%), minimum tillage (36.2%), liming (40%), terracing and cover cropping (95%) and integrated plant nutrient system (31.2%), alongside the traditional stone bunds and mulching. The findings suggested that an increased participation in trainings and contact with extension agents has a significant influence on the importance of capacity building of the farmers regarding sustainable soil conservation technology, innovative cultivation practices, and ensuring frequent extension services to the farmers. Implementing these measures is expected to enable mandarin farmers in Nepal to check annual losses of soil fertility due to soil erosion and landslides, thereby contributing to commercialization of citrus.

Characteristics and development of steepland gullies in the dry valleys of Southwest China

In semi-arid and arid areas, gully erosion is one of the most destructive forms of erosion and causes serious land degradation and resource destruction. Steepland gullies are widely distributed in the dry valleys of southwest China, and their formation is one of the main causes of soil erosion and the destruction of sloping farmland in the region. Previous research on the development of steepland gullies is limited, and further study is needed. In this study, 11 steepland gullies at various stages of development located in Guobu Village, Xide County, Liangshan, Sichuan Province, were selected for investigation using a digital elevation model (DEM) derived from unmanned aerial vehicle data as the primary data source. These data had a spatial resolution of 0.1 m. Fundamental parameters such as the gully length, width, depth, area, and volume were extracted from the remote sensing data. Other characteristic parameters, including the coefficient of main and tributary gullies, vertical gradient, gully elongation, and gully openness, were also investigated. The results indicate a significant linear positive correlation between the gully’s degree of openness and elongation as the gully’s length, width, and depth increase. Furthermore, the vertical gradient and coefficient of main and tributary gullies exhibit power-law relationships with these gully dimensions. The development of steepland gullies was divided into infancy, youth, maturity, and old age based on the use of the gully length as an ergodic indicator in space-for-time substitution. The morphological characteristics of these different stages were quantitatively analyzed, and a proposed mechanism for how the evolution of the gullies proceeds was developed. An empirical model of volume–length erosion was established to investigate the development process of steepland gullies in the dry valleys. It has been observed that the development law of steepland gullies is essentially consistent with the very active stage of typical gully formation, suggesting that steepland gully may represent the initial stage of gully development. The results show that these steepland gullies have their origin in high-intensity rainfall events that are accompanied by the formation of steps and drop water. The effects of gravity erosion and hydraulic erosion then cause the gullies to expand rapidly, forming gullies with a large head and a small tail before they gradually stabilize. The results of this study will help with the understanding of the formation and evolution of steepland gullies and will be of practical significance for the prevention of gully erosion and the protection of sloping farmland in the dry valley region of southwest China.

Selecting ecological attributes for managing within environmental limits: an example of a robust science-policy process in Aotearoa New Zealand

ABSTRACT Aotearoa New Zealand is experiencing continued environmental degradation despite its regulatory settings intended to improve environmental outcomes. A lack of clear environmental limits has made it hard to protect ecological integrity and reduce pressures from the cumulative effects of human activities, even more so in a changing climate. This article outlines an evidence-informed process for selecting attributes – i.e. measurable characteristics – of ecological integrity for use by policy makers in resource management across Aotearoa New Zealand. It describes criteria developed (including urgency and importance, suitability and feasibility) to select an initial suite of attributes through engagement with partners and stakeholders and substantial review. The new attributes are intended to fill key gaps not well covered by existing legislation. Seven new attributes were identified including indigenous vegetation cover, erodible soil stabilisation, sediment mud content, sediment accretion rate, nuisance macroalgae, and saltmarsh and seagrass extent. This small number of attributes are not sufficient on their own to protect ecological integrity by managing within environmental limits, but considered a necessary first step in managing priority issues. A more holistic suite of attributes could be developed later, building from this process that can be adapted depending on the details of any future resource management system.

Reconstructing the late Quaternary soil erosion and dust deposition dynamics in the southern Loess Plateau: Insights from Lake Luyanghu sedimentary records

Investigating the history of wind-dust deposition and soil erosion is crucial for understanding the relationship between geomorphologic formation, monsoon evolution and the current state of soil erosion on the Loess Plateau. This study utilizes a 50-m sedimentary record from Lake Luyanghu (LYH) in the southern Loess Plateau. We developed a chronological framework using optically stimulated luminescence (OSL) dating and stratigraphic comparisons. By applying end-member modeling of grain size, we identified various sediment sources and quantitatively reconstructed the dust deposition fluxes and soil erosion modulus during the late Quaternary. Additionally, we examined the patterns of sediment source evolution with environmental changes at LYH. Our findings reveal that dust constitutes an average of 32.3% of the lake sediments, with an average deposition rate of 40.2 g/cm2/ka. Notably, after the Last Glacial period, dust deposition became the dominant component of the lake sediment. During the Marine Isotope Stages (MIS) 5b, 5d, 4 and 2, enhanced dry climatic conditions, decreased vegetation cover and composition, leading to significant soil erosion. Based on the results of this research, future studies should aim to reconstruct the watershed's erosion and deposition processes throughout geological periods by integrating aspects of lake evolution, such as water levels and developmental stages.

Influence of climate and landscape structure on soil erosion in China's Loess Plateau: Key factor identification and spatiotemporal variability.

Climate and landscape structure are widely recognized as the primary drivers of soil erosion; however, the spatiotemporal variability of their effects remains insufficiently understood, limiting our comprehension of the dynamic processes of soil erosion. To address this gap, this study analyzed soil erosion trends on the Loess Plateau from 2000 to 2018. extreme Gradient Boosting was used to identify key climatic and landscape structural factors, while a geographically and temporally weighted regression model was applied to assess the spatiotemporal variability of these influences. The results indicate a decreasing trend in soil erosion from 2000 to 2008, followed by a sharp increase from 2008 to 2018. Grassland edge density emerged as the most important factor, followed closely by grassland percentage and annual precipitation. Temporally, the positive effect of annual precipitation has been intensifying since 2010, contributing to increased erosion, while landscape structural factors progressively enhanced their hydrological regulatory roles, reflecting dynamic interactions with climate. Spatially, the direction of climatic influences remained generally stable, consistently promoting erosion, although by 2018, the effects of average annual temperature and annual sunshine duration reversed to suppress erosion in specific areas. In contrast, landscape structural influences exhibited greater spatial variability, often fluctuating or reversing depending on topography, human activity, and land use. This variability applied specifically and differentially to each metric of fragmentation and diversity, highlighting the critical importance of trade-offs in landscape management. The findings emphasize the complexity and dynamics of soil erosion in response to climate and landscape structure, suggesting implications for the development of spatially targeted soil erosion control strategies that accommodate the phases of temporal variation.

Land-Use Impacts on Soil Erosion: Geochemical Insights from an Urban Drinking Catchment, South-Central Chile

We investigate the influence of land use and land cover (LU/LC) changes on soil erosion and chemical weathering processes within the Nonguén watershed in the Coastal Cordillera of south-central Chile. The watershed is divided into three sub-basins, each characterized by distinct LU/LC patterns: native forest and exotic plantations. A comprehensive geochemical analysis, including trace elements and lithium (Li) isotopes, was conducted on river water and suspended sediment samples collected from streams within these sub-basins to assess how land management practices, particularly plantation activities, influence the geochemical composition of river systems. Our results show that sub-basins dominated by exotic plantations exhibit significantly higher concentrations of major and trace elements in suspended sediments compared to sub-basins dominated by native forests. The elevated trace element concentrations are primarily attributed to increased physical erosion due to forestry activities such as clear-cutting and soil disturbance, which enhance sediment mobilization. Notably, concentrations of elements such as Fe, Al, and As in plantation-dominated sub-basins are raised to ten times higher than in native-dominated sub-basins. In contrast, sub-basins with native forest cover exhibit lower levels of sediment transport and trace element mobilization, suggesting that native vegetation exerts a stabilizing effect that mitigates soil erosion. Despite the substantial differences in sediment transport and element concentrations, Li isotopic data (δ7Li) show minimal fractionation across the different LU/LC types. This indicates that land use changes impact the chemical weathering processes less compared to physical erosion. The isotopic signatures suggest that physical erosion, rather than chemical weathering, is the dominant process influencing trace element distribution in plantation-dominated areas. The study provides critical insights into how forestry practices, specifically the expansion of exotic plantations, accelerate soil degradation and affect the geochemical composition of river systems. The increased sediment loads, and trace element concentrations observed in plantation-dominated sub-basins, raise concerns about the long-term sustainability of forest management practices, particularly regarding their impacts on water quality in urban catchment areas. These results are of significant relevance for environmental management and policy, as they underscore the need for more investigation and sustainable land use strategies to minimize soil erosion and preserve water resources in regions undergoing rapid LU/LC changes.

A GIS-RS Approach for RUSLE-Based Method of Mean Estimation of Mean Annual Soil Loss of the Tagoloan River Basin, Philippines

Abstract. Soil erosion is a serious environmental concern in Tagoloan River Basin (TRB), a major watershed in Northern Mindanao, Philippines. It leads to soil loss causing detrimental impacts such as decreased soil productivity, nutrient loss, siltation, and water quality degradation among others. These impacts are better understood by estimating the degree of soil loss in the watershed and visualized in a GIS-based and factor-based approach using the Revised Universal Soil Loss Equation (RUSLE) model. Thematic maps of soil loss were generated with factors for rainfall erosivity (R), soil erodibility (K), topographic (LS) consisting of slope length (L) and slope steepness (S), cover management (C), and support practice (P). Factors were calculated separately and multiplied together to develop combined soil loss maps. Results show that TRB has an actual mean annual soil loss of 153.20 tons/hectare/year with 47.15% of the study area having very high to very severe susceptibility to soil loss. Further, a comparison of the potential (RKLS) and actual (RKLSCP) soil loss maps indicates the significance of cover management and support practices to the resulting mean annual soil loss. The present characterized soil loss level maps and its understanding driving forces of soil erosion for the planning of management practices and mitigating environmental hazards in the watershed.