Erosion Dynamics Research Articles

Diffusion Kinetics Theory of Removal of Assemblies’ Surface Deposits with Flushing Oil

The diffusion kinetics theory of cleaning assemblies such as combustion engines with flushing oil has been introduced. Evolution of tar deposits on the engine surfaces and in the lube system has been described through the erosion dynamics. The time-dependent concentration pattern related to hydrodynamic (sub)layers around the tar deposit has been uncovered. Nonlinear equations explaining the experimentally observed dependences for scouring the contaminants off with the oil have been derived and indicate the power law in time. For reference purposes, a similar analysis based on formal chemical kinetics has been accomplished. Factors and scouring parameters for the favor of either mechanism have been discussed. Any preference for either diffusion or chemical kinetics should be based on a careful selection of washing agents in the flushing oil. Future directions of studies are proposed.

Dynamics of soil wind erosion in the Mu Us sandy land (in northern China) affected by cropland reclamation from 2000 to 2020

In recent decades, the wind speed displayed an obvious declining trend in northern China. Under this background, large amounts of grassland and sandy land have been reclaimed into cropland in the Mu Us Sandy Land (MUSL), and whether cropland reclamation will cause an increase in wind erosion has aroused widespread concern. Additionally, there are two reclamation patterns including croplands reclaimed by herdsmen and enterprises in this round of cropland reclamation, whether the different reclamation patterns will induce differential wind erosion is also a scientific question. These questions have influenced the policy of cropland reclamation. Consequently, the Revised Wind Erosion Equation (RWEQ) validated by field observations was applied to simulate the wind erosion of the MUSL from 2000 to 2020. Furthermore, by simulating the wind erosion modulus (WEM) under different scenarios, the climatic fluctuations and cropland reclamation effects on the WEM were distinguished. The results showed that the WEMs of the MUSL decreased during the simulated period. Moreover, the average annual WEM of croplands reclaimed by herdsmen was higher than that reclaimed by enterprises by 18.49% and 12.85% during the 2015 phase (during 2013 to 2017) and 2020 phase (during 2018 to 2020), respectively. The average WEM of the newly reclaimed croplands (reclaimed after 2013) increased 42% relative to the old croplands (reclaimed before 2013), but compared with the original land use types, the WEM of newly reclaimed cropland decreased by 134.55 and 158.94 t/km2/a (annum) during the 2015 phase and 2020 phase, respectively. During the fallow period of the cropland reclaimed by enterprises, the WEM was two times as high as that during planting, so corresponding measures to reduce wind erosion during fallow should be implemented. This study resolves the question of whether cropland will lead to an increase in wind erosion and provides valuable information for reclamation in the MUSL.

Quantification of soil erosion dynamics in the hilly red soil region of Southeast China based on exposed roots

The hilly red soil region (HRSR) of southeastern China is one of the most eroded areas in China. However, the knowledge on regional erosion dynamics and climate drivers still remains fragmental due to lack of long-term observations. Herein, exposed roots from endemic Pinus massoniana, Cunningh lanceolata, and Cinnamomum camphora trees were consulted to explore the evolution of local soil erosion across time and its linkages with climates. Results demonstrated that soil loss induced a distinct diminution in the lumen area of earlywood tracheids/vessels in the exposed roots. Based upon the signals in these root-ring records, we reconstructed average erosion rates for three sheet-erosion sites and found that local eroding conditions have been mitigated after decades-long protection. In addition, we built a chronology of sudden erosive activities since 1971 at the Benggang sites in HRSR with exposed roots. The El Niño-Southern Oscillation (ENSO) acted as a critical trigger for erosive events via modulations of spring-summer precipitation. Ongoing climate change may strongly modulate local soil erosion and an adjustment of mitigation strategies is highly desired to enhance climate change adaption for soil conservation.

Changes in Land-Cover/Land-Use Pattern in the Fortore River Basin (Southern Italy) and Morphodynamic Implications

In Southern Italy, studies dealing with the analysis of multidecadal land-use/land-cover (LULC) changes at the basin scale are scarce. This is an important gap, considering the deep interrelationships between LULC, soil erosion, and river and coastal dynamics. This study provides a contribution in filling this gap by analyzing the LULC patterns and changes in an area of southern Italy, i.e., the Fortore River basin, which occurred between 1960 and 2018. To this end, we conducted a GIS-aided comparison and analysis of LULC data from 1960, 1990, and 2018, respectively. The LULC changes were analyzed at both the basin and the physiographic unit scale. The results showed that most of the LULC changes occurred between the 1960s and 1990s, while from the 1990s onward, great stability in LULC was evident in the basin. The obtained data were mostly coherent with national-, regional-, and basin-scale trends, although some scale-dependent discrepancies were noted. The river and shoreline dynamics fully reflected the duration and the amount of phases of the changes in LULC stability at the basin scale.

A consistent multi-resolution particle method for fluid-driven granular dynamics

Granular dynamics driven by fluid flow is ubiquitous in many industrial and natural processes, such as fluvial and coastal sediment transport. Yet, their complex multiphysics and multi-scale nature challenge numerical models’ accuracy and efficiency. Here, we develop a new multi-resolution mesh-free particle method, based on an enhanced weakly-compressible Moving Particle Semi-implicit (MPS) method, to study the dynamics of rapid fluid-driven granular erosion. We propose and validate a novel multi-resolution multiphase MPS formulation for the consistent and conservative form of the governing equations, including particle stabilization techniques. First, we discuss the numerical accuracy and convergence of the proposed approximation operators through two numerical benchmark cases: the multi-viscosity Poiseuille flow and the multi-density hydrostatic pressure. Then, coupling the developed model with a generalized rheology equation, we investigate the water dam-break waves over movable beds. The particle convergence study confirms that the proposed multi-resolution formulation predicts the analytical solutions with acceptable accuracy and order of convergence. Validating the multiphase granular flow reveals that the mechanical behavior of this fluid-driven problem is highly sensitive to the water-sediment density ratio; the bed with lighter grains experiences extreme erosion and interface deformations. For the bed with a heavier material but different geometrical setups, the surge speed, and the transport layer thickness remain almost identical (away from the gate). Furthermore, while the multi-resolution model accurately estimates the global sediment dynamics, the single-resolution model underestimates the flow evolution. Overall, the qualitative and quantitative analysis of results emphasizes the importance of multi-scale multi-density interactions in fluid-driven modeling.

Climate-vegetation-erosion interactions revealed by the sediments of Huguangyan Maar Lake, southern China

Soil erosion is a serious environmental problem in the red soil region of southern China, yet little is known about the factors responsible and their specific effects on long-term soil erosion dynamics in this region. We addressed this issue via a study of the sediments of Huguangyan Maar Lake (HML), a crater lake in southern China. Our results confirm that the sediments in HML are mainly derived from the erosional input of weathering products of wall rocks, via catchment runoff. Having established the provenance of the HML sediments, the sediment accumulation rate, mass accumulation rate, and geochemical element fluxes were used to reconstruct soil erosion processes in the HML catchment over the past ∼1400 years. The potential drivers of soil erosion were explored, and regional comparisons were made to evaluate the representativeness of this study. The results show that: 1) Higher precipitation before ∼830 CE, coupled with a lower level of human activity, promoted increased vegetation coverage which reduced the rate of soil erosion. 2) Lower precipitation during 830 CE–1390 CE reduced the rate of soil loss. 3) Abundant precipitation was the main cause of the more intense soil erosion during 1390 CE–1878 CE, which may have been exacerbated by the reduced vegetation cover caused by intensive human activity. 4) During 1878 CE–2019 CE, the vegetation cover gradually recovered under the combined effects of vegetation restoration and higher precipitation, which reduced the rate of soil erosion within the HML catchment. Compared to the Chinese Loess Plateau, the erosion level in the HML catchment was relatively low during the period of intensive human activities. Overall, our results contribute to an improving understanding of the driving mechanisms of soil erosion, and they provide a guide for soil conservation measures in southern China.

Atomic oxygen degradation of a fluorine-containing colorless polyimide

Colorless polyimides (PIs) are regarded as the most feasible lens materials deployed in aerospace optical systems due to their light weight, flexibility, transparency, and excellent mechanical properties. However, durability towards atomic oxygen (AO) exposure is a chief concern for externally deployed colorless PI films in low Earth orbit (LEO) environments. In this work, we investigated the degradation behavior of a fluorine-containing colorless PI film with a combination of ground-based AO exposure experiments and reactive molecular dynamics (ReaxFF-MD) simulations. The fluorine-containing colorless PI showed linear erosion dynamics and a constant erosion yield (Ey) of ∼1.4 × 10−24 cm3 atom−1. Microscopic investigations demonstrated an increased surface roughness and shag-like appearance after continuous AO exposure. In addition, spectroscopic transformations resulted from elimination and oxidation processes occurring at specific reaction active sites (C=O, CN, CH, and CF, and CC) and the release of volatile substances. Moreover, the exposed fluorine-containing colorless PI films exhibited gradually deteriorating visible light transmission with increased AO fluence. Furthermore, the ReaxFF-MD simulations demonstrated physical sputtering and bombardment-enhanced chemical reaction models. Considering the limited-scale slab and the system thermal dissipation, the experimental and ReaxFF-MD computational results were largely consistent.

Temporal Dynamic of Soil Erosion and Rainfall Erosivity Within Srou River Basin (Middle Atlas / Morocco)

Soil erosion is a major cause of land degradation worldwide, particularly in arid and semi-arid regions. In Morocco, soil loss is the most prevalent form of land degradation. The Srou river basin, located in the Middle Atlas Mountains of Morocco, has been greatly affected by soil erosion due to physical and human factors. The basin is characterized by an arid and semi-arid climate, with high temperatures, low rainfall, and flash floods, making it particularly vulnerable to soil erosion. Furthermore, the soil is shallow and lacks proper protection from vegetation cover. Livestock and agriculture, mainly consisting of sheep and goats, are the dominant activities in the area. This study employs the rainfall erosivity index (RI) and GIS techniques to evaluate soil erosion in the Srou river basin during three representative years (1995, 1996, and 2010). The objective is to assess the temporal dynamics of soil erosion and its impact in this region. The results indicate that rainfall is irregular and often characterized by intense showers due to climate change. During wet years, the rainfall erosivity index is high, exceeding 200 in 1996 and 2010, while during the dry season of 1995, it was very low, less than 85.

Splash erosion and surface deformation following a drop impact on the soil with different hydrophobicity levels and moisture content.

The splash phenomenon and the scale of the surface deformation of post-fire soils in the variants of various hydrophobicity and moisture content were studied. Splash erosion is the result of the impact of a single water drop and was analysed using high-speed cameras, while the surface deformation was parameterized using a structured light scanner. The extremely water-repellent variant (dry_V) showed distinct differences, expressed primarily in the number of ejected particles, which was 2.5 times higher than in the four soils with lower levels of hydrophobicity. It was also observed that as a result of the drop impact onto an extremely hydrophobic soil surface, a form known as liquid marble was created inside the crater. Soil moisture content determined the manner, scale and dynamics of the splash erosion. In the case of wet soils, the phenomenon proceeded up to five times faster, and as a result of the drop impact, a large number of fine particles were ejected, which reached nearly twice the velocities and three times the displacement distances compared to the dry soil group. However, the particles and/or aggregate splashed on the dry samples were larger, which also translated into the formation of craters up to twice as extensive as those in the wet soils.

The slow downwearing of Madagascar: Inferring patterns and controls on long‐term basin‐averaged erosion rates from in situ10Be at the catchment and regional level

AbstractCosmogenic nuclide analysis of river sediment provides insight into catchment‐wide erosion rates and dynamics. Here, we investigate spatial patterns and controls on 10Be‐inferred erosion rates in Madagascar, a moderately seismically active microcontinent surrounded by passive margins with locally steep topography and a climate that varies from humid tropical to semiarid. We use a compiled dataset of 99 detrital 10Be measurements, 63 of which are new, covering more than 30% of the country and a wide range of topographic, bioclimatic and geologic characteristics. Overall, 10Be erosion rates are low (2.4–51.1 mm kyr−1), with clear differences between regions. The lowest rates are measured on the central highlands ( 8 mm kyr−1), in the Alaotra–Ankay graben ( 11 mm kyr−1) and in the large north‐central catchments ( 11 mm kyr−1). Higher rates are found on the steep eastern escarpment ( 20 mm kyr−1), in the northwest ( 31 mm kyr−1) and in the southwest ( 29 mm kyr−1). A stepwise linear regression model identified elevation as the main factor associated with variations in 10Be erosion rates (lower rates for higher catchments). Random within‐between statistical models (REWB), on the other hand, indicated that the differences between different regions can be explained by differences in river concavity, seismic events and gully (lavaka) densities, whereas additional variation within regions is only linked to seismicity. We find no correlation between catchment or river steepness and 10Be‐inferred erosion rates. Our results indicate that in Madagascar, long‐term erosion rates are overall low and that simple topography‐based models do not explain variations in rates of landscape change inferred from 10Be concentrations in river sediment. We demonstrate that identifying different regions aids in interpreting spatial patterns of erosion rates and that REWB models can be a powerful tool in deciphering environmental controls on 10Be erosion rates.

Soil Erosion Status Prediction Using a Novel Random Forest Model Optimized by Random Search Method

Soil erosion, the degradation of the earth’s surface through the removal of soil particles, occurs in three phases: dislocation, transport, and deposition. Factors such as soil type, assembly, infiltration, and land cover influence the velocity of soil erosion. Soil erosion can result in soil loss in some areas and soil deposition in others. In this paper, we proposed the Random Search-Random Forest (RS-RF) model, which combines random search optimization with the Random Forest algorithm, for soil erosion prediction. This model helps to better understand and predict soil erosion dynamics, supporting informed decisions for soil conservation and land management practices. This study utilized a dataset comprising 236 instances with 11 features. The target feature’s class label indicates erosion (1) or non-erosion (−1). To assess the effectiveness of the classification techniques employed, six evaluation metrics, including accuracy, Matthews Correlation Coefficient (MCC), F1-score, precision, recall, and Area Under the Receiver Operating Characteristic Curve (AUC), were computed. The experimental findings illustrated that the RS-RF model achieved the best outcomes when compared with other machine learning techniques and previous studies using the same dataset with an accuracy rate of 97.4%.

Drainage development on the northern Tibetan Plateau controlled by the Altyn Tagh Fault: Insights from analogue modelling

AbstractAlong the northern margin bounded by the Altyn Tagh Fault, the Tibetan Plateau has been uplifted relative to the Tarim Basin and horizontally extruded to the east for hundreds of kilometres. The Altyn Tagh Fault separates the western Kunlun Shan and Altyn Shan from the Tibetan Plateau, and these two mountain ranges form a topographic window through which river sources from the northern Tibetan Plateau flow into the Tarim Basin. In this study, we designed a specialized geomorphic sandbox to investigate major factors controlling the drainage development on the northern Tibetan Plateau. The modelling results revealed that the Altyn Tagh Fault and preexisting topography played dominant roles in reorganization and divide migration. This strike‐slip fault together with the topographic window has controlled the formation and frequent reorganization of two disproportional fault‐related drainage basins, with the eastern one much larger than the western one. Large‐scale horizontal slip along the fault has resulted in an asymmetric distribution of the drainage area, which showed eastward deviation relative to the topographic window. The modelling results are supported by the observed fluvial landforms as well as evidence of captured channels in nature. Rightward decreasing of the denudation and headward erosion rates in three‐step patterns in the model showed that the slip direction of the main plateau relative to the position of the topographic window influences the erosional dynamics. We conclude that the tectonic activity along the Altyn Tagh Fault, together with the preexisting topography, controlled the drainage development and dynamics in the northern Tibetan Plateau in the late Cenozoic.

Gullies and badlands of India: Genesis, geomorphology and land management

AbstractGully erosion is a formidable land degradation process globally. It is omnipresent across India, wherein two of the largest badlands regions in the world also exist. However, despite being affected by widespread gullying, gully erosion research in India has been rather limited, with key aspects of gully formation, morphologies and dynamics remaining unknown. Through this comprehensive systematic review, we synthesise previous studies on gully erosion in India and in turn highlight pivotal knowledge gaps. The review starts with a discussion of the causal factors of gullying in India, which underlines how gully initiation in several regions was an aftermath of deforestation and overgrazing. Contrastingly, the badlands of Central and Western India have mainly developed in response to natural triggers like neotectonics and Holocene climate change. The section on mapping highlights how mapping methodologies have not only been dictated by the availability of imagery and/or means of data processing, but also the mapping purpose—that is, individual gully channels or entire badlands. Although a few studies applying concepts of fractal geometry to characterise badlands’ geomorphology are innovative and unique, the most striking research gaps we have identified also pertain to understanding and quantification of gully geomorphology and erosion dynamics in different regions of India. Our review reveals that gullies of peninsular India have been the least studied, followed by those of the Himalayan and Sub‐Himalayan region. Although the literature provides interesting examples of linkages between badlands development and the wider geomorphic evolution of the landscape, better chronological understanding is required to disentangle the relative importance of natural and anthropogenic drivers of landscape change in India's badlands. Large‐scale mapping of gully characteristics, quantification of gully morphologies, gully erosion rates and its share in catchment sediment budget across various physiographic regions or river basins of the country also constitute important areas for future research.

Palaeosols as stratigraphic proxies and palaeosurface markers in distributive fluvial systems

Palaeosols can be used as stratigraphic proxies, palaeosurface indicators, and palaeorelief reconstitution tools, as they reflect a complex interrelationship between sedimentation, erosion, non-deposition, and pedogenesis. The objective of the article was to estimate the relative time of formation of palaeosols of the Marília Formation, to determine the periods of non-deposition and non-erosion, indicative of stabilities on the surfaces, and to interpret the profiles as markers of palaeosurfaces in distributive fluvial systems (DFS) of the Late Cretaceous of Brazil. Eleven sections of the Marília Formation (S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, and S11) were described, comprising forty-three profiles. The pedotypes classification (polygenic, compound, and cumulative) and the determination of palaeosols' relative formation time and residence time were based on the specialized literature. The reconstitution of pedosedimentary cycles considered the dynamics of sedimentation, erosion, and pedogenesis. Eight sedimentary cycles and 45 pedosedimentary cycles were interpreted. All the Maastrichtian pedosedimentary cycles of the Bauru Basin corresponded to depositional cycles interspersed with erosive and pedogenic processes. Palaeosols with argillic (Btk, Bt, Bss) and calcic (Bkm) horizons, developed from fluvial sandstones, evolved in processes predominantly after the deposits, with later erosive processes. However, although most of the profiles developed in periods between deposits and erosion, pedogenic processes also occurred concomitantly with the sedimentary cycles, favouring the formation of polygenetic profiles, which presented the longest pedogenic cycles in chronological terms. Palaeosols with argillic horizons can be important stratigraphic landmarks. They represent stopping moments in erosion and sedimentation of up to 1.374 My, thus consisting of the closing of high-frequency depositional cycles. Although palaeosols can demonstrate relief inversion and pedotypes with Bt-horizons can indicate ancient regional surfaces, the complete reconstitution of the topography becomes more possible at the local level, in a palaeoslope approach, due to the variability of pedofacies.

Effects of geomorphological processes and phytoclimate conditions change on forest vegetation in the Pomeranian Bay coastal zone (Wolin National Park, West Pomerania)

The functioning of plant associations, including forest associations, in the coastal cliff edge zone of the Pomeranian Bay in the Wolin National Park (WNP) is determined by short-term factors related to the dynamics of erosion and denudation processes and long-term phytoclimatic conditions’ changes. The study presents a temporary analysis of the occurrence of sea abrasion and water and aeolian erosion, based on the applied hydrometeorological threshold values. The influence of changes in phytoclimatic conditions on the development and productivity of coastal forests with the dominant species of Fagus sylvatica was also presented. Assessments of spatial susceptibility to erosion of the cliff coast and the existing plant associations were also carried out in conditions of the risk of coast erosion. It was found that 55% of the cliff edge zone of the Pomeranian Bay of the WNP and the forest associations (mainly Luzulo pilosae-Fagetum) occurring there are in the zone of particular risk of increased erosion and denudation processes. In addition, unfavourable trends in changes in phytoclimatic conditions in the 21st century were found, which reflect climate changes unfavourable to the development of beech forests on Wolin Island.

Spatiotemporal Evolution of Soil Erosion and Its Driving Mechanism in the Mongolian Section of the Yellow River Basin

Soil erosion is a popular environmental issue that threatens sustainability. Influenced by multiple factors, such as climate, soil, and terrain, Baotou City, which is in the Bohai Sea Economic Circle and the Economic Belt along the Yellow River, has a severe ecological environment. In this study, revised soil and soil wind erosion equations were used to evaluate the soil erosion dynamics in Baotou City, and the potential driving factors of soil erosion were further investigated. Results showed that from 1990 to 2020, the water erosion modulus in Baotou City increased first, decreased, and then increased, with great fluctuations in annual changes. The wind erosion modulus decreased continuously, with a small fluctuation in annual changes. Water erosion in 2020 was more severe, with 4840.5 km2 added to the desert steppe and 1300.5 km2 reduced in the Yellow River Basin. The extent of wind erosion was significantly reduced, and the phenomenon of wind erosion improved. Meteorological factors are the primary factors that influence soil water erosion and soil wind erosion. Meanwhile, adverse climate changes can alter physical and chemical soil properties and vegetation coverage, thereby indirectly influencing soil erosion. With the implementation of the Beijing–Tianjin sandstorm source control, the farmland return to forest project, the ecological restoration and protection project at the southern and northern foothills of Daqingshan Mountains, grazing prohibition, and rotation grazing—including grassland awards, subsidies, and other policies and systems during this period—the overall deteriorating trend of the grassland ecological environment in Baotou was contained, grassland ecological system functions were improved, wind and sand erosion was prevented, biodiversity was maintained, and the ecological service functions of soil and water conservation were guaranteed.

Monitoring erosion in tropical savannas from C-band radar coherence

Increased erosion related to climate and/or land cover change has adverse impacts on terrestrial and aquatic ecosystems. Mapping of erosion hotspots improves our ability to identify and potentially remediate the most active erosion sources. The topical savannas of the Great Barrier Reef catchments, in northeast Australia, are generating excessive sediment yields, primarily from gully erosion. To reduce the adverse impacts on marine ecosystems, there is an urgent need to identify priority erosion hotspots and implement mitigation measures. While repeat airborne LiDAR surveys allow subtle topographic change detection, they are cost-intensive for catchment-scale applications and their applicability is constrained by data avalability and detection treshold of ground level change. In contrast, satellite-based radar imagery can allow large scale tracking of geomorphic change at high temporal resolution. Here we apply a new method based on Sentinel-1 C-band radar images and Coherence Change Detection (CCD), where large stacks of interferometric coherence images are subdivided with rain gauge time-series for separation of erosion-rich and erosion-free coherence information. After correcting the former with the latter, the resulting corrected coherence maps are compared with differential elevation models derived from multitemporal LiDAR, regional scale gully delineation maps, maps of gullying potential and in-situ field verification. Our results demonstrate the promising potential of this technique in detecting gully erosion hotspots. The coherence loss indicating erosion/deposition is well detected in wide gully morphologies, however, the line-of-sight angle does not allow penetration into narrow linear gullies. Further, CCD detects sheetwash or rill erosion occurring in areas identified as at risk of gully expansion, which is commonly below detection threshold for multitemporal LiDAR datasets. When used with LiDAR-derived geomorphic change mapping and gullying potential maps, CCD allows identification of gully erosion dynamics and forecasting gully evolution and creation, which is critical for supporting mitigation measures.

Structure and biogeochemical process of microaggregates in a water source area of China’s South-to-North Water Diversion Project according to different land use types

Soil biogeochemical processes have the potential to impact water quality in source areas of water diversion projects. This study aimed to explore the differences in biochemical processes and mechanisms at the microaggregate scale for different land use types in the water source area of China's Middle Route of the South-to-North Water Diversion Project. The study compared four typical land use types—forests, shrublands, terraces, and cultivated land—by characterizing the microaggregates using various analytical techniques, including scanning electron microscopy (SEM), SEM-EDS plane scan analysis, X-ray diffraction (XRD), X-ray fluorescence (XRF) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. Microaggregates from forests and shrublands had a flocculent spatial structure, while those from terraces had a nondirectional plate-like spatial structure, and those from cultivated land had a laminar spatial structure. Additionally, elements such as Mg, Al, and Fe were enriched in clay particles when combined with microaggregates. The mineral composition of clay varied significantly between different land use practices, with illite, chlorite, anorthite, albite, and quartz present in higher proportions in terraces and cultivated land than in forests and shrublands. Moreover, the contents of transitional elements such as Ti, Fe, Zn, Y, and Zr increased with each successive land use practice. Soil organic matter (SOM) was observed to decline in the order of forest > shrubland > terraces > cultivated land. Over-tillage appeared to be the primary mechanism of organic matter loss due to long-term tillage. The results of this study provide valuable insights into soil erosion and chemical transport dynamics. The mineral composition and spatial structure of microaggregates are important determinants of soil biochemical processes and mechanisms, which can influence water quality. The findings suggest that forest and shrubland management practices may be more conducive to maintaining soil health and water quality in source areas of water diversion projects.

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

Soil erosion is a vector of disturbances to agricultural productivity and economic development in the western highlands of Ethiopia. Yet, tough vegetation cover loss swapped to other land uses could have amplified the soil loss rate at which land cover change preceded, but little is known about their effects on soil loss in the Limu-Seqa watershed. This study was designed to evaluate the historical trends of the effects of land use-land cover change on soil erosion dynamics as a threshold for potential monitoring of soil loss. Satellite image data of 1987, 2002, 2021, and DEM-20 m resolution were used. The RUSLE model was applied with primary parameters to generate soil loss. Findings show that average annual soil loss increased from 4.5 in 1987 to 13.5 t ha−1 yr−1 in 2002 and surpassed to 45.35 t ha−1 yr−1 in 2021 as a result of LULC changes, particularly the transition of forest and overgrazed land to cropland (43.83%) and dense-forest to poor-open-up forest (6.92%) between 1987 and 2021. Soil loss during the recent study period was substantially affected by a substantial LULC change, from forest to cropland. The severe and very severe erosion risk categories jointly cover more than half of the entire catchment, which contributes to two-thirds of the total mean annual soil loss in the watershed, which is found to be over and above soil loss tolerance (SLT) in Ethiopia and tropical regions. Therefore, given the robust economic and political status of priority conservation measures, red hues areas are significant.

Performance of soil and water conservation practices in the erosion evolution process, runoff dynamics and surface roughness

AbstractSoil and water conservation practices are used widely to prevent soil erosion and protect soil and water resources, which is significant for ecological restoration and food security. However, rill evolution processes, erosion and deposition characteristics and critical hydrodynamic parameters need more research. In order to investigate the effect of soil and water conservation practices on soil erosion dynamics, simulated rainfall experiments were undertaken in a laboratory on 15° loess slopes with engineering measures (fish‐scale pits, FSPs), tillage measures (artificial digging, AD; contour ploughing, CP) and bare slope (CK). The results showed that: (1) during rill erosion, hillslopes with FSPs, CP and AD were more likely to develop wide and shallow rills, while a bare slope (CK) was more likely to develop narrow and deep rills. At the end of the experiment (cumulative rainfall was about 150 mm), headward retreat erosion dominated the AD slope (maximum rill length: 3.27 m), side‐wall expansion erosion dominated the CP slope (maximum rill width: 0.522 m) and bed incision erosion dominated the CK (maximum rill depth: 0.09 m); (2) soil and water conservation practices reduced surface erosion and sediment transport and runoff velocity. However, the positive effects disappeared when rainfall amounts exceeded 82.5, 105 and 127.5 mm for FSPs, CP and AD, respectively; (3) for runoff kinetic energy and runoff shear strength of 3 J and 1.5 N/m2, respectively, soil and water conservation measures had greater anti‐erosion abilities than CK; (4) as rainfall duration increased, surface roughness, runoff rate and sediment concentration increased on the CK and FSP treatments, but decreased on the CP and AD treatments. This study has important implications for managing different soil and water conservation measures based on rainfall conditions and offers a deeper understanding of soil erosion processes.