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The Weihe Basin is one of the regions with the highest concentrations of ground fissure development and the most serious disasters in China. Hidden ground fissures are formed in the shallow soil layer due to preexisting fissures generated by tectonism, hidden ground fissures suddenly exposed to the surface after heavy rainfall. Because the details of the water erosion process cannot be replicated by geological survey methods, the erosion and extension mechanism has not fully developed and the discontinuous medium numerical simulation method is well suited for simulating large deformations and facilitates a microscopic perspective in elucidating the underlying causal mechanisms. This paper deploys the discrete element method (DEM)–computational fluid dynamics (CFD) fluid–solid coupled method modeling the growth process of hidden fissures containing different soil types (sand and clay) under heavy rainfall, revealing a mechanism for the development of hidden fissures into surface fissures. The findings include: (1) the emergence process of hidden fissures into surface fissures under heavy rainfall can be summarized into four stages: subsurface erosion into hidden holes, traction into arches, collapse into sinkholes, and horizontal extension; (2) the emergence process of clay is slower than that of sand due to the constraint of cohesion; (3) the shape of the bottom seepage point affects the fissure emergence process, which is an important factor in the macroscopic performance of the exposed surface fissures. The intuitive and reproducible DEM-CFD coupled modeling used in this paper possesses important reference value for the study and prevention of water erosion ground fissures. [ABSTRACT FROM AUTHOR]

Background: Granular flows are common on the Qinghai–Tibet Plateau and the Hengduan Mountains in China, and their dynamic process processes have obvious erosional and entrainment effects. On the one hand, the volume of the granular flow increases by a factor of several or ten, which significantly increases its ability to cause a catastrophe; on the other hand, the eroded loose material affects the granular flow dynamics process and changes its state of motion. Methods: In this paper, the dynamic mechanism of granular flow erosion and entrainment is investigated by DEM simulation. Purpose: The effects of different substrate materials and substrate boundary conditions on granular flow erosion and entrainment are analyzed, and the effects of material mixing caused by erosion and entrainment on the state of motion of granular flow are discussed. It was verified that the kinetic mechanisms of granular flow erosion and entrainment includes impact erosion, ploughing, and shear abrasion. Results: And discovered that small matrix particle size, small matrix boundary friction, and small matrix thickness lead to stronger ploughing and shear abrasion; Large matrix fractal dimensions result in stronger ploughing and weaker shear abrasion, and the granular flow does not entrain large amounts of material to the accumulation zone. Meanwhile, the dynamics of erosion and entrainment of granular flow were investigated, and the results showed that: 1. The greater the erosion rate, the greater the velocity and kinetic energy of the granular flow, the greater the distance traveled, and the smaller the apparent friction angle (i.e., the greater the mobility). 2. The amount of small granules in a granular flow changes its fluidity, the more small granules there are, the more fluid it is. 3. The fit reveals that the substrate fractal dimension has the strongest effect on the velocity and kinetic energy of granular flow, followed by substrate thickness and substrate boundary friction. [ABSTRACT FROM AUTHOR]

Soil and water conservation and protection are of great importance to China, as the source of the Pearl and Xiang Rivers, and the main rare earth mining area, the ecology of Dongjiang River Basin, is very fragile. In this paper, the Chinese soil loss equation and the Geodetector method are used to analyze the spatial and temporal patterns and the impact factors of soil erosion in this area from 2016 to 2020. The results show that (1) Soil erosion intensity in the Dongjiang River Basin from 2016 to 2020 is mainly mild, with the soil erosion intensity in the Dongjiang River Basin in 2016 being the largest in five years. (2) The erosion modulus shows an increasing trend with the increase of slope. In terms of vegetation, when the vegetation cover is <30%, the soil erosion modulus is the largest, which is easy to induce soil erosion. When the vegetation cover is >60%, the soil erosion modulus is the smallest, which effectively slows down the occurrence of soil erosion. Rainfall is proportional to the soil erosion modulus and soil erosion. (3) The results of Geodetector indicate that the single factor sizes are land use > vegetation > slope > precipitation, and interaction factors all show a nonlinear enhancement. (4) The proper allocation of land use types, the prohibition of steep slopes for cultivation, and the restoration of forestry can effectively prevent and control soil erosion in the area. Core Ideas: Chinese soil loss equation enabled us to quantify soil erosion patterns.Geodetector unravels the underlying mechanisms responsible for spatial heterogeneity.The investigation highlighted the significant impact of intense rainfall events on steep slopes.Our analysis illustrates the shifting landscape of soil erosion within the Dongjiang River Basin.Our research sheds light on the key drivers behind this phenomenon. [ABSTRACT FROM AUTHOR]

Freeze–thaw (FT) erosion intensity may exhibit a future increasing trend with climate warming, humidification, and permafrost degradation in the Qinghai–Tibet Plateau (QTP). The present study provides a reference for the prevention and control of FT erosion in the QTP, as well as for the protection and restoration of the regional ecological environment. FT erosion is the third major type of soil erosion after water and wind erosion. Although FT erosion is one of the major soil erosion types in cold regions, it has been studied relatively little in the past because of the complexity of several influencing factors and the involvement of shallow surface layers at certain depths. The QTP is an important ecological barrier area in China. However, this area is characterized by harsh climatic and fragile environmental conditions, as well as by frequent FT erosion events, making it necessary to conduct research on FT erosion. In this paper, a total of 11 meteorological, vegetation, topographic, geomorphological, and geological factors were selected and assigned analytic hierarchy process (AHP)-based weights to evaluate the FT erosion intensity in the QTP using a comprehensive evaluation index method. In addition, the single effects of the selected influencing factors on the FT erosion intensity were further evaluated in this study. According to the obtained results, the total FT erosion area covered 1.61 × 106 km2, accounting for 61.33% of the total area of the QTP. The moderate and strong FT erosion intensity classes covered 6.19 × 105 km2, accounting for 38.37% of the total FT erosion area in the QTP. The results revealed substantial variations in the spatial distribution of the FT erosion intensity in the QTP. Indeed, the moderate and strong erosion areas were mainly located in the high mountain areas and the hilly part of the Hoh Xil frozen soil region. [ABSTRACT FROM AUTHOR]

The upper reaches of the Yellow River in China, influenced by erosion of the Yellow River and tectonic activities, are prone to landslides. Therefore, it is necessary to investigate the existing landslide traces. Based on visual interpretation on high-resolution satellite images and terrain data, supplemented and validated by existing landslide records, this paper prepared the most complete and detailed landslide traces inventory in Jianzha County, Huangnan Tibetan Autonomous Prefecture, Qinghai Province, to date. The results indicate that within the study area of 1714 km², there are at least 713 landslide traces, ranging in scale from 3,556 m2 to 11.13 km², with a total area of 134.46 km². The total landslide area excluding the overlap area is 126.30 km². The overall landslide point density and area density in the study area are 0.42 km[sup -2] and 7.37% respectively. The maximum point density and maximum area density of landslide traces in the area are as high as 5.69 km-2 and 98.0% respectively. The landslides are primarily distributed in the relatively low-elevation northeastern part of Jianzha County, characterized mainly by large-scale loess landslides, with 14 landslides exceeding 1x10[sup 6] m². This inventory not only supplements the landslide trace data in the transition zone between the Qinghai-Tibet Plateau and the Loess Plateau, but also provides an important basis for subsequent landslide risk zoning, response to climate change, and landscape evolution. Additionally, it holds significant reference value for compiling landslide inventories in similar geological environments. [ABSTRACT FROM AUTHOR]

The problems of gully and soil erosion caused by large-scale urban construction and agricultural development in China have become more and more serious in recent years. In an effort to solve this problem, a series of gully stabilization and highland protection projects have been carried out on the Loess Plateau, and this has resulted in a large number of high-loess-filled-slopes (HLFSs). Although these filled slopes uses several different mitigation measures, the HLFSs have been eroded and destroyed under the action of water. In order to study the influence of different mitigation measures on the stability of HLFSs and their failure process, this paper uses a flume test of the effects of various mitigation measures on this failure process. The results show that: (1) the failure processes of slopes with different mitigation measures are obviously different. Slope deformation u with a declining gradient mitigation mainly occurs on the surface of the slope body, and although slope erosion is quite serious, the slope does not fail as a whole. Slopes with a stepwise drainage channel mitigation show little erosion, but material can easily slide along the horizontal drainage channels. (2) The slope deformation process is correlated with changes in pore-water pressure. When local instability occurs, there is always a pre-process of continuously rising pore-water pressure. When a failure occurs, the pore-water pressure of the soil at each position of the slope body suddenly fluctuates under instantaneous excitation. (3) The response of soil pore pressure and the development characteristics of tension cracks affect the deformation of the slopes, which is also the cause of the differences slope instability caused by different mitigation measures. These research results provide reference for the protection of HLFS engineering projects from heavy rains. [ABSTRACT FROM AUTHOR]

Featured Application: This paper provides a simulation method for extreme precipitation events in geotechnical slopes (spatio-temporal connections, forecasting, generation, impact analysis, and vulnerability and risk assessment). Our improved methods provide a valuable tool for engineering disaster early warning and contribute to a better understanding of hydrodynamic processes in general. Coal gangue is one of the largest solid wastes in the world. In previous studies, the influence and mechanisms of rainfall infiltration on coal gangue slope stability and possible rain erosion have been studied through theoretical analysis, numerical simulation, and modelling, and the results have indicated that discontinuous discrete element methods are the most suitable for determining the erosion mechanism of coal gangue slopes. In this study, we take a Guizhou coal gangue slope as a general case, use three-dimensional Particle Flow Code (PFC3D) as the key method, and combine discrete element fluid–structure coupling technology with optimized erosion shear failure theory to determine the erosion failure mechanism of coal gangue slopes. We investigate a coal gangue slope near the electric power plant in Panzhou City, Guizhou Province (China) as a case study, and conduct a comprehensive analysis of the erosion induced by the corrosion damage mechanism. We use the PFC3D method, combined with optimized rain erosion shear failure theory, for our investigation. The applied methods mainly consider dynamic inversion of the erosion process, as well as the changes in coordination number, porosity, unbalanced force, and energy dissipation. The scour damage type of the studied gully is intermittent fragmentary damage, with the following inferred damage sequence: Center–bottom–top of the slope. The entire erosion damage process can be divided into three stages: catchment–fracture, erosion–accumulation, and piping–penetration failure. In the first stage of erosion, the force chain fracture is the most severe. The maximum kinetic energy reaches 25 MJ and the coordination number decreases from 5.3 to 4.0, whereas the porosity increases from 0.42 to 0.45. Unexpected lateral erosion and expansion occur at 40–60 m (in the central slope) in the y-direction of the slope, the unbalanced force reaches 7500 N, and the peak porosity is increased by 10%. This paper provides a simulation method for extreme precipitation events in geotechnical slopes (contributing to spatio-temporal connections, forecasting, generation, impact analysis, and vulnerability and risk assessment). Our improved methods provide valuable tools for engineering disaster early warning, and contribute to a better understanding of hydrodynamic processes in general. [ABSTRACT FROM AUTHOR]

Purpose: Cemented conglomerate accumulation is a weak and heterogeneous medium that occurs in western China. It consists mainly of argillaceous cement that loses strength rapidly upon contact with water, leading to collapse instability failure. Its deformation failure mechanism is complex and poorly understood. In this paper, the erosion failure mechanism of cemented conglomerate accumulation is investigated. Design/methodology/approach: The collapse failure process after erosion of the slope foot for typical cemented conglomerate accumulation is studied based on field investigation using the particle discrete element method. And how the medium composition, slope angle and cementation degree influence the failure mode and process of the cemented conglomerate accumulation is examined. Findings: The foot erosion of slope induces a tensile failure that typically manifests as "erosion at the foot of slope – tensile cracking at the back edge of slope top – integral collapse." The collapse failure is more likely to occur when the cemented conglomerate accumulation has a higher rock content, a steeper slope angle or a weaker cementation degree. Originality/value: A model based on rigid blocks and disk particles to simulate the cemented conglomerate accumulation is developed. It shows that the hydraulic erosion at the foot of the slope resulted in a different failure mechanism than that of general slopes. The results can inform the stability management, disaster prevention and mitigation of similar slopes. [ABSTRACT FROM AUTHOR]

The Weihe Basin is a crucial part of the Fenwei Graben System and is a typical example of an extensional fault basin. Over time, the region has been developed around 212 ground fissures, with the majority of them being associated with heavy rainfall. These water-eroded ground fissures have caused serious damage to farmland, houses, and roads, with the Liangjiacun ground fissures, Meiyuancun ground fissures, and Dizhentai ground fissures being the most known. To understand the developmental characteristics and formation mechanisms of water-eroded ground fissures in the Weihe Basin, we utilized a variety of methods, including ground surveys, mapping, trenching, drilling, and geophysical exploration. These three ground fissures are distributed along corresponding fault zones, with their orientations being closely linked to local topographic changes. Additionally, the trenching profiles showed that all three typical ground fissure zones have distinct hidden holes above the paleosol. The formation of these ground fissures is closely associated with tectonic activity and heavy rainfall, with soil ruptures resulting from tectonic activity becoming the dominant channels for surface water infiltration. Furthermore, the erosion caused by heavy rainfall accelerates the rupture and expansion of ground fissures in the shallow subsurface. This paper is a valuable resource for disaster prevention and mitigation strategies aimed at mitigating the damage caused by ground fissures in the Weihe Basin. [ABSTRACT FROM AUTHOR]

Lacustrine sediments are good recorders of palaeoenvironment changes and have been widely studied in recent years. The study of lacustrine sediments in Southwest China will improve our understanding of the complex environmental evolution history of Southwest China. Therefore, this paper presents a high-resolution rock magnetism study from the Pengtun drilling hole (PT2) in the Heqing Basin, Southwest China. The results show that the dominant magnetic minerals in the PT2 drill core are magnetite, maghemite and haematite. The magnetic susceptibility (χ) of the upper part of the core (0–13.5 m) is lower than that of the lower part (13.5–33.5 m). There is no maghemite in the upper sections. The minerals with high χ values have the characteristics of pseudosingle-domain (PSD), single-domain (SD), superparamagnetic (SP) and multidomain (MD) grains. The magnetic domains are widely distributed, and the particles are coarser. When χ is low, the magnetic domains of the different samples vary greatly, and the particles are finer. Combined with the magnetic and nonmagnetic characteristics of the sediment, we infer that the change in χ in the PT2 drill core is related to clastic input, water erosion, and reductive dissolution. [ABSTRACT FROM AUTHOR]

Both vegetation coverage rates and arrangement patterns have important influences on erosion. Very little previous research focuses on the impacts of spatial vegetation distribution patterns on erosion. The slope-gully system was taken as the research object, which is composed of a 5.0 m long hillslope with a slope gradient of 20° and a 3.0 m long gully slope with a gradient of 50°. A series of scouring experiments with two inflow discharges (3.2 L min−1, 5.2 L min−1) was carried out. The effects of the flow discharges, spatial grass arrangement patterns (US, MS, and DS represent the presence of grass covering on up-hillslope, middle-hillslope, and down-hillslope, respectively) and grass coverage rates (0%, 30%, 50%, 70%, and 90%) on runoff and sediment were studied in this paper. The results indicated that either runoff or sediment yielding was significantly decreased with the grass coverage rates increasing and with the variation of grass arrangement patterns on a hillslope. While grass coverage had more effectiveness in controlling erosion compared with runoff reduction, and DS can control erosion more effectively than US and MS erosion controlling. For the gully slope, erosion significantly increased with the grass coverage rates increasing no matter how the grass arrangement patterns on the hillslope. Therefore, both different grass coverage and different grass arrangement patterns have an influence on erosion processes; any research that only takes care of the single factor mentioned above is not enough to reveal the effects of grass on erosion. In the process of erosion control in the Loess Plateau, taking effective measures both on the hillslope and gully slope will be effective methods of reducing soil erosion. [ABSTRACT FROM AUTHOR]

Gully erosion is a major threat to ecosystems, potentially leading to desertification, land degradation, and crop loss. Developing viable gully erosion prevention and remediation strategies requires regular monitoring of the gullies. Nevertheless, it is highly challenging to automatically access the monitoring results of the gullies from the latest monitoring data by training historical data acquired by different sensors at different times. To this end, this paper presents a novel semi-supervised semantic segmentation with boundary-guided pseudo-label generation strategy and adaptive loss function method. This method takes full advantage of the historical data with labels and the latest monitoring data without labels to obtain the latest monitoring results of the gullies. The boundary-guided pseudo-label generation strategy (BPGS), guided by the inherent boundary maps of real geographic objects, fuses multiple evidence data to generate reliable pseudo-labels. Additionally, we propose an adaptive loss function based on centroid similarity (CSIM) to further alleviate the impact of pseudo-label noise. To verify the proposed method, two datasets for gully erosion monitoring are constructed according to the satellite data acquired in northeastern China. Extensive experiments demonstrate that the proposed method is more appropriate for automatic gully erosion monitoring than four state-of-the-art methods, including supervised methods and semi-supervised methods. [ABSTRACT FROM AUTHOR]

The outer bank slump blocks play a fundamental role in modulating the rate of bank erosion, and consequently, have a profound influence on many geomorphic and ecologic processes in meandering streams, e.g., channel evolution and habitat creation. To date, no adequate research has been developed regarding how these blocks, partially strengthened by roots of herbaceous plants, impact the near-bank flow velocity, bank erosion, and migration of streambanks. This paper analyzes 246 slump blocks in a meandering stream on the Marqu Meadow, China. Aerial surveys were conducted once a year from 2018 to 2021 and the lateral migration rates (M) of streambanks are estimated by superimposing the current-year drone imagery onto its previous-year counterpart. When compared to the outer bank segments lacking slumps, our research findings indicate that the bank segments exhibiting slumps demonstrate a reduction of 57 % and 43 % in the maximum and average bank erosion rates, respectively. Overall, the wider blocks provide stronger bank protection; nevertheless, they may also introduce or enhance local scouring in their vicinity, thereby increasing the heterogeneity of bank erosion rates. To elucidate this complex influence mechanism, we simulate the three-dimensional flow velocity field of a ~100 m meandering bend containing three slump blocks using the MIKE-3 model. Furthermore, we compare one-year bank migration distance with and without the blocks by correlating the lateral migration distance of outer banks to the longitudinal gradient of near-bank velocity. The paper provides valuable insights into the complex interplay between flow dynamics and streambank behavior in real-world settings, thereby enhancing the effectiveness of future management and restoration practices. • 246 slump blocks were analyzed in a meander on Marqu Meadow, China. • Slump blocks can persist for years but may be washed away in high flows. • The outer bank slump blocks play a vital role in modulating bank erosion rates. • Slump blocks protect outer banks by redistributing the high flow and secondary flow. • Slump blocks help protect bank overall but it may introduce scour in their vicinity. [ABSTRACT FROM AUTHOR]

Soil erosion is a major environmental problem of global concern. In the Loess Plateau region of China, erosion of loess slopes is one of the major modes of soil erosion, causing serious erosional problems. Most current studies of loess slope erosion use qualitative analyses from field investigations, while quantitative analyses from experimental physical simulations are relatively rare. This paper takes slope erosion, which is the most typical mode of loess erosion, as the starting point and investigates the hydraulic erosion process for different initial states using small-scale physical simulations. The slope erosion process can be generalised into two stages: rapid erosion, and slow and uniform erosion. Results of the physical simulations suggested that the initial dry density is negatively correlated with the erosion rate, but the initial water content is positively correlated with the erosion rate. The results of the study are not only of practical significance for the prevention and control of soil erosion on loess slopes, but also of theoretical significance, as they reveal the development of slope gully erosion. [ABSTRACT FROM AUTHOR]

A prediction method applicable to erosion-prone areas of fluorine chemical pipelines is herein proposed. By summarizing the common working conditions in the fluorine chemical industry, a computational fluid dynamics (CFD) model for industrial pipelines is established, and three-dimensional numerical calculations of the flow field in the pipelines are carried out to analyze the characteristics of the hydrodynamic parameters and phase distribution in the flow field, as well as the erosion rate distribution in different areas of the pipelines. The areas in the pipeline that are susceptible to erosion are predicted based on the results. The method has universal applicability and has been applied in many large petrochemical companies. It achieves the function of predicting the areas of severe pipeline erosion in a scientifically sound manner. This paper also details the application of the method in a distillation oil and gas pipeline of a large oil and gas company in western China. [ABSTRACT FROM AUTHOR]

Based on potential vorticity (PV) thinking, northeast China cold vortex (NCCV) corresponds to an upper‐level high PV anomaly from stratospheric PV downward intrusion. Within a vortex, latent heating from precipitation would produce a vertical dipole of PV anomalies that would affect structures and evolution of the vortex. In this paper, three‐dimensional structures and evolution of NCCV and, effects of latent heating from precipitation along bent‐back, cold and warm fronts on them are investigated based on convection‐allowing simulations for an intense NCCV case during 8–17 June 2012. Trajectory analysis shows that the negative upper‐level diabatic PV anomaly from bent‐back frontal precipitation, near the vortex center, is the dominant contributor to erosion of high PV in the vortex core region as it is advected in, leading to the weakening of the vortex. The negative PV anomalies along the cold and warm fronts, at the east‐to‐southeast side of the vortex, are mostly advected downstream away from the NCCV. In the middle troposphere, positive PV anomalies are primarily generated along fronts and the accumulated positive PV anomalies filling the vortex region help to reinforce the low‐level cyclonic circulation. The lower‐level PV is affected by surface heating and cooling through their effects on static stability, but such effects are periodic and create mainly diurnal variations. The NCCV eventually decays as the upper‐level vortex weakens due to significant PV erosion. Plain Language Summary: Northeast China cold vortex (NCCV) is responsible for much of the warm season precipitation in northeast China. Based on convection‐allowing simulations of a characteristic case, the distribution and effects of latent heating release from precipitation in bent‐back, cold and warm frontal regions on the structures and evolution of potential vorticity (PV) within the NCCV are studied. Negative upper‐level PV anomalies generated at the bent‐back front are primarily responsible for the filamentation and erosion of high PV in the core of NCCV, leading to the weakening of the vortex. At middle‐to‐low levels, positive PV anomalies generated reinforce the low‐level circulations. However, the lower‐level PV exhibits a significant diurnal cycle, which is mainly affected by the surface heating and cooling through reducing static stability at daytime and increasing static stability during night. The overall system eventually decays as the upper‐level vortex weakens. Key Points: Precipitation in northeast China cold vortex produces negative upper‐level potential vorticity (PV) anomaly that weakens the upper level cold vortexNegative PV anomaly produced at the bent‐back front is the dominant contributor to the erosion of upper‐level high PV in the vortex centerLower‐level vortex is enhanced by positive PV anomaly from precipitation, and the PV has diurnal variations due to surface heating/cooling [ABSTRACT FROM AUTHOR]

As the most important gold producer in China, the Northwest Jiaodong Peninsula is famous for its large gold deposits. In recent years, the discovery of gold mineralization has reached a depth of 4 000 m below the surface in this region. It has attracted significant interest from explorers about the prospecting potential at greater depths. Besides, the current deep drilling shows that the prospecting effect in the west portion is better than the region to the east. Does it imply that there is a difference in prospecting potential between the east and the west? This paper seeks to address the issue through fission track thermochronology on apatite and zircon to reveal the temperature-time evolution relationship of rock mass and to inverts their thermal evolution history. In addition, this study analyzes the transformation of ore deposits after mineralization, quantitatively calculates the uplift-erosion rate of rock mass, and summarizes the preservation law of ore deposits. Based on the thermal history simulation of the apatite fission track, our results show that the Guocheng gold belt has experienced three stages of thermal evolution: 108–74, 74–27, and 27–0 Ma. The uplift and cooling processes of the three-stage tectonic uplift events are the results of multi-stage Pacific plate accretion. The calculated total denudation depth of the gold deposit in the Guocheng gold belt from Cretaceous to the present is about 3.4–5.3 km. The metallogenic depth of the ore body in the gold belt is 5.6–8.0 km, which indicates that the ore body in the Guocheng gold belt has suffered a significant degree of denudation. It is speculated that the location with less denudation in the southwest has greater prospecting potential. Our results quantitatively identify the uplift and denudation of the deposit after mineralization, which provides a new theoretical reference for regional mineralization, deep prospecting and exploration. [ABSTRACT FROM AUTHOR]

Soil erosion resistance is influenced by intrinsic soil properties and multiple external factors. This study investigated the effect of tea planting age on soil resistance to flowing water erosion (reflected by rill erodibility (Kr) and critical shear stress (tc)) in Three Gorges Reservoir Area. One slope farmland (as the control) and five tea plantations cultivated for 3 to 34 years were selected for sampling sites. The results indicated that bulk density (BD), soil cohesion (Coh), water stable aggregate (WSA), mean weight diameter (MWD), soil organic carbon (SOC), litter density (LD), and root mass density (RMD) increased generally with tea planting age. Compared to the control, Kr of tea plantations reduced by 71.1%-85.3%. The temporal variation in soil erosion resistance was controlled greatly by the variations in most near-surface characteristics. Kr decreased with WSA, Coh, LD, RMD, and SOC following a power function (P < 0.01); tc increased with MWD, LD, RMD, and SOC as an exponential function, with BD a power function, and Coh a logarithmic function (P < 0.01). In this study, Kr could be simulated well by WSA and LD with a power function, and tc could be simulated well by MWD and RMD with an exponential function. [ABSTRACT FROM AUTHOR]

The hydrological and mechanical properties of granitic residual soils can be significantly altered by periodical wetting and drying (W-D) cycles. The soil structure degradation induced by W-D cycles can lead to soil mass failure and collapsing gully erosion in granitic hilly slopes in south China. However, limited attempts have been made at a comprehensive investigation of the effects of W-D cycles on the structure degradation of granitic residual soils, especially at the pedon scale. The purpose of this paper is to investigate the structural degradation of granite soils induced by W-D cycles and explore its potential influence on the development of collapsing gully erosion. The granitic soil properties, including hydraulic properties, shear strength, and disintegration characteristics, were performed after W-D cycles. The results indicated that the W-D cycles altered the soil pore structure, leading to variations in soil hydraulic properties. Specifically, with increasing alternate W-D cycles, the initial saturated water content and residual water content decreased, while the saturated hydraulic conductivity increased. Meanwhile, increasing W-D cycles contributed significantly to variations in cohesion and internal friction strength by decreasing the shear strength variables, especially the soil cohesion strength. Correspondingly, soil disintegration was increased during W-D cycles. Furthermore, most degradation of soil structure was recorded within the first two cycles of W-D. The obtained results indicate that the W-D cycles weaken soil structure, increase rainwater infiltration, decrease soil shear strength and disintegration resistance, and accelerate soil erosion. A vicious cycle of granitic slope failure induced by W-D cycles is eventually formed. This study provides useful information about the mechanism of soil mass failure and collapsing gully erosion in granitic hilly slopes. [ABSTRACT FROM AUTHOR]

• Hillslope erosion dynamic model integrating vegetation effect was established. • Unified baseline parameters were obtained across different land uses. • Effect of vegetation on soil detachment and sediment transport was revealed. • Contribution rates of vegetation to sediment reduction along slopes were quantified. Developing a process-based soil erosion model that comprehensively considers the effects of vegetation is complex but crucial for evaluating sediment reduction during vegetation restoration. Current understanding of the effect of vegetation on sediment reduction along hillslopes across different land uses is limited. In this paper, we developed a dynamic model of hillslope erosion that integrates the effects of vegetation on soil detachability and hydrodynamics (VED) based on the feedback mechanism between soil detachment and sediment transport. The VED was calibrated and validated with runoff plot data for woodland, grassland, and farmland in the Wuding, Yan, Jing and Wei Rivers of the Loess Plateau in China. Unified baseline parameters and decay coefficients of vegetation were obtained. The model validation results indicated that the coefficient of determination, Nash–Sutcliffe simulation efficiency and relative error ranged from 0.59 to 0.99, 0.56 to 0.90, and −45.99 % to 46.36 %, respectively. The decay coefficients for soil detachment capacity (Φ), sediment transport capacity (T c), and the sediment reduction effect of vegetation exhibited the following order: woodland > grassland > farmland. Compared with VED, existing process-based soil erosion models failed to effectively characterize the influence of vegetation on Φ and T c on the Loess Plateau, with differences of several orders of magnitude. The individual contributions of runoff, soil detachability, and hydrodynamics with vegetation impact on sediment yield were quantified by VED. The contribution rates of vegetation to sediment reduction decreased gradually with increasing slope length because the soil detachment capacity of bare slopes exceeded that of vegetated slopes, resulting in a faster increase in sediment yield. The contribution rates of vegetation to sediment reduction for woodland, grassland, and farmland with 20 %–60 % vegetation covers were 66.75 %–99.95 %, 57.43 %–99.63 %, and 27.91 %–88.63 % in the boundary conditions of this study, respectively. The results reveal the potential for integrating VED into other distributed watershed hydrological and sediment models to assess the effects of vegetation restoration on sediment reduction at a watershed scale. [ABSTRACT FROM AUTHOR]

Soil erosion is a challenge worldwide, including in China. The dendrogeomorphic method was applied, for the first time, at Xiaolong Mts in Gansu Province to obtain a quantitative estimate of the soil erosion rate. The dataset built in this pilot study allowed the identification of exhumation texture in exposed roots between 1967 and 2002. The calculated mean erosion rate estimates (Era) ranged from 2.6 to 16.5 mm yr−1 and showed an increase with the slope steepness (s). The best fitting linear model (Era = 0.043(±0.017) × s + 3.09(±1.04); R² = 0.20; R²adj = 0.16; F = 6.18; p = 0.02) could be used in future research to determine and to map soil denudation in this part of the Xiaolong Mts. Notable associations were found between erosive rainfalls and root exhumation events. Daily (Rx1day) and 5-day (Rx5day) precipitation totals of 56 and 73 mm, respectively, seem to be critical thresholds which if exceeded will always induce root exhumation in the same year or in the consecutive season in the forest of the Xiaolong Mts in the studied period. [ABSTRACT FROM AUTHOR]

The progressive reservoir construction and operation have led to nonstationary sediment load response to water discharge and a new equilibrium between sediment supply and transport of a river system. However, an increase in the reservoir impoundments on the nonstationary behaviors could demonstrate significant temporal variability over the river system. In this study, the statistical relationships of annual sediment load with both streamflow and reservoir storage capacity during 1956–2018 are analyzed in the Upper Yangtze River Basin (UYRB), China. The trend and abrupt detection analyses show that the significant departure of annual sediment load to annual water discharge occurs only when the cumulative storage capacity over the course of progressive impoundments reaches a critical value for the cascade reservoirs in UYRB. The critical storage capacity gradually appeared in the 1980s, 1990s, and 2000s, accounting for the sharp increases of small- and medium-sized reservoirs in the tributaries and large-sized reservoirs in the mainstem. Once the critical storage is exceeded, the capacity to trap sediment increases exponentially with the cumulative storage. The significant increase of trapped sediment (e.g., 26%–88% of the free-flow capacity in the tributary and mainstem stations) has led to the shift of sediment-controlling factors from water discharge to the impounded runoff index. The significant reduction of sediment transportation and the altered dominant factors of sediment load could result in the steady erosion of channels and coastlines and adversely impact ecosystems in the downstream Yangtze River. Human activities, especially dam construction, have severely altered the global river system. Dams disrupt the continuity of the river, inevitably altering the natural transport of sediment and reducing sediment loads. Since the 19th century, a large number of reservoirs have been built in the upper reaches of the Yangtze River where water resources are abundant. When the cumulative storage capacity over the course of progressive impoundments reaches a critical value for the cascade reservoirs in the Upper Yangtze River, the capacity for trapping sediment increases exponentially with the cumulative storage. The significant increase in trapped sediment has led to a shift of sediment-controlling factors. The significant reduction of sediment transportation and the altered dominant factors of sediment load could lead to several environmental problems, such as the limited availability of nutrients in the middle and lower reaches, river bed erosion, and the destruction of benthic habitat. The change in the relationship between sediment, water discharge, and reservoir capacity can provide a reference for the environmental management and protection of the Yangtze River. [ABSTRACT FROM AUTHOR]

In croplands, soil erosion resistance varies with both natural processes and human disturbances. To clarify the temporal variation in soil erosion resistance, nine cropland plots with three treatments (continuous fallow, fallow after tillage and tillage with corn) were established in the dry–hot valley region of China. A total of 144 field runoff simulation experiments were conducted from May to October to measure the soil detachment rate (Dc), rill erodibility (Kr) and critical shear stress (τc). The results revealed that the natural dry—wet alternation had little influence on the continuous-fallowed soil erosion resistance. On the other hand, the tillage disturbance that occurred in May sharply increased the Dc and Kr to 2.24 and 3 times that of the continuous-fallow treatment, respectively. Then, the erosion resistance could be enhanced with surface consolidation for the fallow-after-tillage treatment. However, after three months of fallow, the Kr was still 89.5% of the fresh tilled soil. In contrast, crop growth could significantly improve aggregate stability and reduce the Kr to 38.2% in August and even further to 23.7% in October compared to the fresh tilled soil. It could be concluded that crop growth is more efficient in enhancing erosion resistance than the mechanical effect. The above results would benefit from the accurate modeling of cropland soil erosion dynamics and guide agricultural management in dry–hot climate regions. [ABSTRACT FROM AUTHOR]

Granites, widely distributed in the Earth's crust, undergo pedogenic processes, shaping diverse soil-mantled landscapes influenced by climatic factors in different regions. Investigating the geochemical signatures in granite weathering profiles across varying climatic conditions provides valuable insights into the intricate interplay between weathering and landscape evolution. In this study, the geochemical features, particularly major and rare earth elements, and the weathering degree of granites across temperate to subtropical regions in China were examined. The results indicated significant variations in the geochemical characteristics of granite weathering profiles, both at a pedon and regional scale (p < 0.01). With increasing hydrothermal conditions from north to south, soil pH shifted from neutral to acidic, accompanied by the leaching of major elements (K2O, Na2O, CaO, and MgO) and the enrichment of Al and Fe. The total rare earth elements (∑REEs) ranged from 75 to 352 ppm, and light rare earth elements (LREEs) from 71 to 317 ppm, exhibiting less significant variations across the study area, while heavy rare earth elements (HREEs) showed higher concentrations in the subtropical region (3 to 35 ppm). Plagioclases dominated the weathering process in temperate regions, with K-feldspar progressively increasing and, eventually, dominating from temperate to subtropic regions, resulting in a shift in clay minerals from 2:1-type in the temperate to 1:1-type in the subtropic. The chemical index of alteration (CIA) and comprehensive weathering index (W) increased from fresh rock to residual soils along the weathering profiles and from north to south across the study area, ranging from 50.72 to 97.44 and 35.11 to 70.62, respectively. The intensified granite weathering degree was significantly influenced by climatic conditions (p < 0.05), especially the multi-year average precipitation (22.4%) and relative humidity (9.1%) (p < 0.01). Gully erosion on the granite weathering mantle was concentrated in granites with a comprehensive weathering index exceeding 52.51, and the spatial variation of the granite weathering degree aligned with the spatial distribution of gully density across the study area. [ABSTRACT FROM AUTHOR]

The time-effective mapping of erosion gullies is crucial for monitoring and early detection of developing erosional progression. However, current methods face challenges in obtaining large-scale erosion gully networks rapidly due to limitations in data availability and computational complexity. This study developed a rapid method for extracting erosion gully networks by integrating interferometric synthetic aperture radar (InSAR) and the relative elevation algorithm (REA) within the Huangfuchuan Basin, a case basin in the northern Loess Plateau, China. Validation in the study area demonstrated that the proposed method achieved an F1 score of 81.94%, representing a 9.77% improvement over that of the reference ASTER GDEM. The method successfully detected small reliefs of erosion gullies using the InSAR-refined DEM. The accuracy of extraction varied depending on the characteristics of the gullies in different locations. The F1 score showed a positive correlation with gully depth (R2 = 0.62), while the fragmented gully heads presented a higher potential of being missed due to the resolution effect. The extraction results provided insights into the erosion gully networks in the case study area. A total of approximately 28,000 gullies were identified, exhibiting pinnate and trellis patterns. Most of the gullies had notable intersecting angles exceeding 60°. The basin's average depth was 64 m, with the deepest gully being 140 m deep. Surface fragmentation indicated moderate erosive activity, with the southeastern loess region showing more severe erosion than the Pisha sandstone-dominated central and northwestern regions. The method described in this study offers a rapid approach to map gullies, streamlining the workflow of erosion gully extraction and enabling efficiently targeted interventions for erosion control efforts. Its practical applicability and potential to leverage open-source data make it accessible for broader application in similar regions facing erosion challenges. [ABSTRACT FROM AUTHOR]

Pelton turbine, with its unique advantages in high mountainous region especially in the southwest of China, has received more and more attention. This paper focuses on the erosion influence to the hydraulic characteristics by Euler particle tracking model. Two-phase numerical simulation results are compared with the model experiment results and are proved to be accurate. Solid particle is then added in the flow and three-phase flow is solved. Particle parameters (silt particle size, concentration) were considered to investigate the mechanism of silt erosion on Pelton turbine distribution system including distributor, bifurcation tubes, and nozzle structure. It proves that erosion destroys the vortex structure in bifurcation tubes. As the particle's diameter increases, discharge in different bifurcations appear more uniform. With the particle flow, a strong collision phenomenon appears at nozzle seat. As the particle's diameter increases, the erosion strengthens accordingly. This study reveals that the particle influence induces erosion which is important to be considered during the design and operating procedures in the whole life of Pelton turbine. [ABSTRACT FROM AUTHOR]

Pelton turbine, as its working principle, can perform in the high head condition especially in the southwest mountainous region in China. When the flow contains silt, it will induce the erosion in the bucket and needle structure which affects the efficiency and furthermore the service life. This paper performs unsteady air-liquid-solid three-phases simulation focusing on the distribution tube and needle parts. Volume of Fluid (VOF) method is used for capturing the free surface flow, at the same time, silt particle is simplified as the sphere particle and simulated through the Discrete Particle Model (DPM). Furthermore, flow detail and erosion information are obtained by conjugating both the former methodologies. Finally, particle size is analyzed in order to investigate the effect of erosion characteristic to the flow passage of Pelton turbine which aims to improve the turbine efficiency. [ABSTRACT FROM AUTHOR]

There are many sand-laden waters in China, and the wear of hydraulic structures caused by sand-laden water diversion has been paid more and more attention. Taking the spillway of a reservoir as the research object, the numerical model of erosion wear caused by sediment-laden particle flows on the spillway was established by using the computational fluid dynamics (CFD) method, VOF (Volume of Fluid) multiphase flow model and DPM (Discrete Phase Model). Through the simulation analysis of the spillway's overall erosion, the distribution of the spillway erosion wear was obtained. Then, according to the main wear parts, the single variable, such as sediment diameter, sediment concentration, flow velocity and gate opening degree, was changed to study the erosion amount of the spillway and the distribution law of the spillway erosion parts. The results show that the main erosion sites of the spillway are at the bottom of the gate chamber and the middle section of the spillway. The maximum erosion increases linearly with the increase in sediment concentration. With the increase in sediment concentration, the sediment concentration changed from 1 kg/m3 to 6 kg/m3, and the maximum erosion of the spillway increased from 2.58 × 10−7 kg/m2 to 1.53 × 10−6 kg/m2. The erosion at the bottom of the spillway and gate leaf increases first and then decreases with the increase in sediment diameter and reaches the maximum value when the particle size is 0.002 mm. The erosion at the bottom of the spillway and the gate leaf increases with different growth trends as the flow velocity increases, when the flow velocity increases from 2 m/s to 9 m/s and the maximum erosion amount at the bottom of the spillway increases from 3.66 × 10−7 kg/m2 to 1.14 × 10−6 kg/m2, and the maximum erosion of the gate leaf increased from 1.66 × 10−8 kg/m2 to 8.98 × 10−6 kg/m2. The erosion amount at the bottom of the spillway increases with the increase in the gate opening between 0 and 3 m and tends to be stable when the gate opening is greater than 3 m. The maximum erosion position moves to the rear part of the spillway with the change in the gate opening. The change in the gate opening has no obvious effect on the erosion amount of the gate leaf but only changes the area of the gate erosion part. Thus, the erosion wear distribution of spillway under different work conditions is summarized, and the qualitative study between the erosion wear and the distribution of sediment diameter, sediment concentration, flow velocity and gate opening degree is made. [ABSTRACT FROM AUTHOR]

In the mudslide prone areas of western China, concrete piers were severely damaged by washing.In our previous research, the anti-abrasive UHPC prepared with saturated prewet high titanium heavy slag sand (ST-UHPC) is proposed to prevent such damage. And we studied the effect of grinding and erosion on the performance of ST-UHPC before, but the mechanism has not been studied in depth In order to study the microstructure evolution of ST-UHPC cement by the grinding and erosion, we use XRD, SEM, 27Al NMR, 29Si NMR test methods in this paper. By this way, we studied the effects of shock and salt erosion on hydration products composition, migration and transformation of Al-containing hydration products, hydration degree of cement and C-A-S-H gel microstructure. The results showed that the impact of bedload damaged the microstructure of UHPC. Then the damage of UHPC microstructure accelerates the transport of aggressive ions. Next, SO 4 2- erodes from the site of damage and produces expansive erosion products such as gypsum and calcareous vanadite. The erosion of SO 4 2- and Mg2+ resulted in the dealuminization and decalcification of C-A-S-H gel in UHPC cement and mechanical properties degradation. Thus, the expansion damage of UHPC and the impact damage of UHPC structure are aggravated. So the microstructure damage of UHPC was further aggravated. Under the action of impact, the water impacting material forms various chemical bonds with the C-A-S-H substrate. The chemical bonds results in the evolution of C-A-S-H microstructure. In conclusion, the structure of C-A-S-H substrate deteriorates obviously under the coupling effect of scouring and erosion. And the impact resistance of C-A-S-H substrate decreases significantly. • The anti-abrasive UHPC prepared with saturated prewet high titanium heavy slag sand was proposed. • XRD, SEM, 27Al NMR, 29Si NMR were used to study the microstructure evolution of ST-UHPC. • The microstructure evolution of UHPC was studied by molecular dynamics simulation. [ABSTRACT FROM AUTHOR]

Coastal dunes record the evolutionary process of coastal dynamic geomorphological systems, and provide valuable information on climate change, sea level changes, environmental evolution. These dunes are essential for global change research. In view of the dynamic changes in coastal dunes caused by extreme weather, coastal erosion and human activities, we propose a comprehensive evaluation method for coastal dune evolution, which monitors Haiyang Ten Thousand Meters Beach of China from three perspectives: point, line, and surface. This method integrates LiDAR, GNSS, and RS technologies. The research results indicate that between 2016 and 2018, 68% of the GNSS point measurements in 22 survey profiles of coastal dunes were eroded along the foreshore. During 2011-2020, the coastline based on the RS data basically remained stable; only the estuarine district underwent significant changes, and the overall average change rate was 1.32 m/a. The overall morphological evolution of coastal dunes obtained by LiDAR in 2018 was relatively stable, but there was a weak erosion trend in the foreshores of the coastal dunes. This study is beneficial for providing precise targets for remediating and restoring eroded coastal areas in the future. Furthermore, it can provide technical support and informational information for ecological environment protection, coastal erosion prevention and environmental evolution in the Haiyang Ten Thousand Meters Beach Marine Nature Reserve. [ABSTRACT FROM AUTHOR]

Granite residual soil is widely distributed in the southern coastal areas of China, and the slopes of granite residual soil are prone to instability and failure under the alternating action of rainfall and drying, which will cause great disasters to human society. In order to study the response mechanism of granite residual soil slopes under the alternating action of rainfall-drying-static-rainfall (RDSR), this study conducted indoor scaling model tests to analyze the response during dry and wet cycles. This study presented the response process of the slope under the influence of dry and wet cycles and discussed the change laws of slope deformation, water content, and matric suction. The results show that, under the alternating action of rainfall-drying-static-rainfall, 1) the network cracks on the slope form a dominant channel for rainwater seepage, which is the main reason for the rapid decline in soil anti-sliding ability within a short time; 2) at a rainfall intensity of 1.7-2.4 mm/min, the erosion effect of rain on the slope is obviously stronger than that of osmotic erosion, and the surface erosion failure of the granite residual soil slope tends to occur without an obvious sliding surface; 3) after the loss of matric suction over a certain period, the phenomenon of channeling and loss failure on the slope serve as a sufficient condition for slope instability failure but is not a necessary condition. The above research results are expected to provide the basis and reference for preventing and controlling landslide hazards in granite residual soil slopes under similar conditions. [ABSTRACT FROM AUTHOR]

Freeze–thaw erosion is one of the three major soil erosions in China, including wind erosion and hydraulic erosion, which leads to the destruction of the natural environment, the imbalance of economic development, a threat to personal safety, and irreversible disaster to the country and people. China's permafrost area accounts for about one-fifth of the country's land area, and the seasonal permafrost area accounts for half of China's land area, mainly concentrated in the Qinghai–Tibet Plateau, Xinjiang Province, Heilongjiang Province, Gansu Province, and other regions. In order to establish an evaluation system for the ecological function reserve of the Greater Hinggan Mountains, nine evaluation indicators were selected from the perspectives of topography, climate, soil, and vegetation conditions. GIS technology, a multiple collinearity test, and principal component analysis were used to comprehensively evaluate the freeze–thaw erosion in the ecological function reserve of the Greater Hinggan Mountains. This study categorized the evaluation results into five intensity levels, from micro to severe. Finally, the degree of influence of different influencing factors on freeze–thaw erosion and the interactions between the factors were analyzed using a geographic detector. The results showed the following: (1) The intensity of freeze–thaw erosion in the study area gradually increased from west to east, and the comprehensive evaluation results were −0.2552 to 0.7581. Overall, moderate, severe, and mild erosion accounted for 29.83%, 25.9%, and 21.54% of the total area of the freeze–thaw zone, respectively. (2) Soil moisture content and the annual range in temperature were the main factors contributing to freeze–thaw erosion. The degree of influence of the two effects on freeze–thaw erosion (q = 0.5997) was better than that of the single-factor effect. [ABSTRACT FROM AUTHOR]

The Naozhi deposit of northeast China comprises intermediate-sulfidation epithermal-style veins and subeconomic, porphyry-style Cu mineralization hosted by dioritic to granitic plutons, which formed at ca. 130 Ma. These intrusive phases were fed by magmas that ponded at mid- to upper-crustal levels and were finally emplaced at < 0.6 kbar based on amphibole geobarometry. The magmas were moderately oxidized (∆NNO − 0.35 to 2.21; with NNO being the nickel–nickel–oxide buffer) and water-rich (mostly > 4 wt. %), and likely experienced a relatively prolonged evolution in the shallow crust rather than at depth. Magma devolatilization and fluid exsolution at shallow-crustal levels lead to decreases in both oxygen fugacity (log ƒO2 − 10.96 to − 14.13) and water content (6.53 to 2.26 wt. %) at < 2.5 kbar pressures. Thermochronological data of zircon and apatite, thermal history modeling, and geological preservation record complex time–temperature histories of the mineralized intrusive rocks, from the cooling of the parent magma itself through burial by younger volcanic rocks to protracted erosion with time. It is estimated that < 2 km of pre-mineralization material was removed from the top of the Naozhi magmatic–hydrothermal system from the Early Cretaceous to present. A 108 ± 2 Ma volcanic event possibly tilted the hydrothermal system, but buried the ores, protecting them from extensive erosion. [ABSTRACT FROM AUTHOR]

Inappropriate soil management accelerates soil erosion and thus poses a serious threat to food security and biodiversity. Due to poor data availability and fragmented terrain, the landscape pattern of garden erosion in tropical Xishuangbanna is not clear. In this study, by integrating multi-source satellite imagery, field investigation and visual interpretation, we realized high-resolution mapping of gardens and soil conservation measures at the landscape scale. The Chinese Soil Loss Equation (CSLE) model was then performed to estimate the garden erosion rates and to identify critical erosion-prone areas; the landscape pattern of soil erosion was further discussed. Results showed the following: (1) For the three major plantations, teas have the largest degree of fragmentation and orchards suffer the highest soil erosion rate, while rubbers show the largest patch area, aggregation degree and soil erosion ratio. (2) The average garden erosion rate is 1595.08 t·km−2a−1, resulting in an annual soil loss of 9.73 × 106 t. Soil erosion is more susceptible to elevation and vegetation cover rather than the slope gradient. Meanwhile, irreversible erosion rates only occur in gardens with fraction vegetation coverage (FVC) lower than 30%, and they contribute 68.19% of total soil loss with the smallest land portion, indicating that new plantations are suffering serious erosion problems. (3) Garden patches with high erosion intensity grades and aggregation indexes should be recognized as priorities for centralized treatment. For elevations near 1900 m and lowlands (<950 m), the decrease in the fractal dimension index of erosion-prone areas indicates that patches are more regular and aggregated, suggesting a more optimistic conservation situation. [ABSTRACT FROM AUTHOR]

Intertidal bar systems (IBSs) are ubiquitous geomorphic features on beaches and play an important role in nourishing and protecting beaches. IBSs can also pose a significant threat to nearshore swimmers and ships. Therefore, studying the evolution of IBSs will yield valuable insight in understanding the dynamic nature of beaches, provide help in protecting beaches from current widespread erosion, and provide early warning of potential hazards. However, the data used by previous approaches are commonly site-specific and labor-intensive (or expensive), which restricts their application. This paper introduces a new approach for studying the long-term evolution of IBSs based on free satellite imagery. This satellite approach uses three methods, namely bar, trough, and breaker methods, to directly recognize the planar positions of IBSs. This approach has low requirements on satellite images, therefore it is conducive to making full use of the precious historical satellite images to study the highly dynamic evolution of IBSs in recent decades, which cannot be measured and photographed again. Based on the terabytes of free satellite imagery, this approach can be used on almost all beaches in the world, which will greatly expand the study object pool and facilitate the selection of study objects in different types of marine conditions. This paper also introduces how to use the satellite approach based on a case study. The case study quantitatively revealed the forming, migration, decay, and distribution of the IBSs around the Feng River mouth in China, evaluated the errors of the satellite-derived position and migration rate, analyzed the main factors affecting their evolution, and discussed the main factors influencing their evolution and their influence on the evolution of adjacent beaches. • A new satellite approach was provided to study the evolution of intertidal bar systems. • The approach uses bar, trough, and breaker methods to recognize the position of IBS. • The long-term evolution of IBSs around a river mouth was revealed and analyzed. [ABSTRACT FROM AUTHOR]

• Progress of research on Benggang erosion was systematically analyzed. • Research deficiencies exist in understanding of erosion mechanism, prevention and evaluation. • Possible future research directions and priorities were identified. • Hydraulic-gravitational composite erosion mechanism and modelling is the main future research direction. Benggangs are a special type of severely eroded landform in southern China. They cause severe damage to soil resources, which has had a large negative impact on local ecological environments and people's lives. Benggang erosion has received abundant attention in the past few decades, but few studies have systematically summarized and analyzed the progress, deficiencies and future directions of research of Benggang erosion. The purpose of this paper is therefore to analyze the progress of research on Benggang erosion, summarize the research deficiencies and propose future research directions and priorities. Benggangs gained attention in the 1960s, and studies of Benggang erosion have achieved rich results, including the characteristics of parental materials, spatial variation of soil properties in Benggang areas, mechanisms of the occurrence and process of Benggang erosion, dynamic monitoring of Benggang erosion, estimation of erosion volume, measures for controlling Benggang erosion and evaluation of their effectiveness. These studies have improved our knowledge and understanding of the basic attributes, occurrence, development, and factors influencing Benggang erosion and have provided a scientific basis for the optimal arrangement of measures for conserving soil and water and the rational development and effective management of Benggangs. We nevertheless believe that deficiencies remain in the aspects of the optimization of monitoring methods, mechanism of composite erosion, control of erosion and evaluation of the effectiveness of controlling Benggang erosion under the current level of development of research on soil erosion and the high standard of ecological protection. Further studies are necessary in the following areas: space-air-ground integrated technology for optimizing the monitoring of Benggang erosion; mechanism of hydraulic-gravitational composite erosion and the construction of models; research, development and application of new material for the prevention and control of Benggang erosion and development of a system for evaluating the effectiveness of erosion control. These research topics can supplement and enrich the content of traditional research on Benggang erosion and are very important for the restoration of ecological environments and improving ecological services and functions in areas with Benggang erosion. [ABSTRACT FROM AUTHOR]

The basal cavity of a rock block formed due to differential weathering is an important predisposing factor for rockfall in hard–soft interbedded rocks, which induces an eccentricity situation at the base of the rock block. Rock block falling due to the non-uniform distribution with the failure modes of toppling or sliding is defined as biased rockfall in this study. Taking into account the non-uniform stress distribution due to the eccentricity effect, a new analytical method is proposed for three-dimensional stability analysis of biased rockfall. The development of non-uniform stress distribution stress calculated by this analytical method was verified by numerical simulation. The biased rockfall progresses from partial damage of the soft underlying layer, caused by non-uniform distributed stress, to toppling and sliding of overhanging hard rock block due to overall unbalanced force. Therefore, a set of factors of safety (Fos's) against partial damage (compressive and tensile damage of the soft underlying layer) and overall failure (toppling and sliding of the hard rock block) are used to determine the rockfall susceptibility level. The analytical method is applied and validated using biased rockfalls on the northeastern edge of the Sichuan Basin in southwest China, where a significant number of rockfalls consisting of overhanging thick sandstone and underlying mudstone occur. The evolution process of biased rockfalls is divided into four stages, initial state, basal cavity formation, partially unstable and failure. The proposed method is validated by calculating Fos's of the typical unstable rock blocks in the study area. As the cavity continues to grow, the continuous retreat of mudstone causes stress redistribution between the hard and soft rock layers. This results in damage to the underlying soft rock layer due to the development of the non-uniform distribution, ultimately leading to the failure of the hard rock block. The critical retreat ratio is determined to be 0.33, which is used to classify the low and moderate rockfall susceptibility in the eastern Sichuan Basin. The proposed analytical method provides insights into the evolution of biased rockfall and a means for early identification and susceptibility assessment of rockfall. [ABSTRACT FROM AUTHOR]

Using high-precision CT scanning equipment, two series of tests on frost and salt weathering were conducted to investigate the characteristics of pore change in tuff. Experiments on frost and salt aging were performed with pieces of tuff from the same area of southeast China. One set of tuff samples was soaked in saturated sodium sulfate or magnesium sulfate solutions for 60 days. Another set of tuff samples were subjected to 60 freeze–thaw cycles after being submerged in saturated sodium sulfate or magnesium sulfate solutions for 48 h. Our study demonstrates that processes such as salt erosion and freeze–thaw affect the pore evolution of tuffs significantly. Tuff lost 1.56% of its mass after being submerged in magnesium sulfate solutions for 60 days, while tuff submerged in sodium sulfate solutions gained a negative 0.33% of its mass. After 60 freeze–thaw cycles, the mass loss of tuff samples immersed in sodium sulfate, magnesium sulfate, and distilled water solutions was 3.52%, 3.58%, and 3.82%, respectively. The average porosity of the magnesium sulfate and sodium sulfate test groups increased by 6.59% and 4.14%, respectively, when the number of days of salt erosion was extended from 10 to 60 days. The average porosity of tuff samples immersed in magnesium persulfate and sodium sulfate solutions increased by 2.25% and 2.18%, respectively, as the number of freeze–thaw cycles went from 10 to 60. [ABSTRACT FROM AUTHOR]

Numerical modeling of landform evolution is the key to understanding the formation of land surfaces. However, landform evolution occurs under certain initial topographic conditions, while existing landform evolution models often use a plane or a randomly produced surface to establish the initial topographic conditions. This misunderstanding of the initial topographic conditions causes the landform evolution results to deviate greatly from the real terrain. Therefore, the initial topographic conditions must be reconstructed and integrated into the current numerical landform evolution model. In this paper, the Loess Plateau of China was selected as a typical sample area. The paleotopography was reconstructed and integrated into the numerical landform evolution model. Based on the evolutionary mechanism of loess landforms, modules of surface erosion, matter diffusion and precipitation were selected to construct a numerical model of loess landform evolution. Moreover, randomly produced terrain was used as the initial conditions during the landform evolution process and compared with the paleotopography-constrained evolution results. In addition, the results of the landform evolution process were evaluated with different terrain factors, and the uncertainty of the model was assessed by comparing different model conditions. The results show that, due to the control of paleotopography, the evolution results can maintain the main morphological structure of valleys in the loess landscape. Without considering the paleotopography, a large difference exists between the evolution results and the true ground terrain. These results show that paleotopography is an important feature of loess landform evolution modeling and is indispensable for reasonably expressing the process of landform evolution. Finally, the numerical modeling of loess landform evolution with the consideration of paleotopography can not only help to achieve a better understanding of the loess landform evolution process but also provide a reference for feature dependent landform evolution modeling in different landform applications. • Paleotopography affects the evolution of loess landform in the Loess Plateau. • We integrate the paleotopography into the numerical loess landform evolution model. • Our results can maintain the main morphological structure of loess landform. • Our research provides a reference for feature-concerned landform evolution modeling. [ABSTRACT FROM AUTHOR]

A land resource asset (LRA) table is highly valued by the Chinese government for resource management. However, most of China's researches on LRA table focused on theoretical construction. The difficulty in obtaining data hinders the practice and promotion of existing methods, and it limits the selection of data for many practical studies. Thus, this study proposes a land value quantification (LVQ) model that is suitable for a large spatio–temporal scale background to solve the above problems. Based on this model, the LRA table in the middle reaches of the Yellow River was successfully compiled. The results indicated that: (1) the assets of regional land resources were in an unbalanced development state; (2) the LRAs in the middle Yellow River had changed frequently; (3) there were significant spatial differences in the distributions of various types of LRAs in the middle reaches of the Yellow River; and (4) topography and soil erosion were the main factors restricting optimal regional land resource spatial allocation. Based on the research findings, this study provides scientific policy recommendations for the optimal allocation and sustainable development of land resources in the middle reaches of the Yellow River. Moreover, the LVQ model proposed in this research provides a model reference for LRA accounting with large spatial and temporal scales in China and similar regions. [ABSTRACT FROM AUTHOR]

Hyperpycnal flow deposits, one of the most important deep‐water gravity‐flow deposits in lacustrine basins, have become the research focus in recent years. However, the sedimentary characteristics and depositional model of hyperpycnal flow deposits in lacustrine basins remain unclear due to the differences of depositional settings between lacustrine and marine environments. Hyperpycnal flow deposits observed in the middle of the third member of the Shahejie Formation (Es3z) in the Bonan Sag, Bohai Bay Basin, Eastern China, provide a rare case study to reveal the characteristics and depositional model in lacustrine basins. For the first time, detailed core analysis, high‐resolution 3D seismic data, petrology and grain size analysis were used to unravel the characteristics and depositional model of hyperpycnal flow deposits in this study. Twelve lithofacies, six bed types and four bedsets (corresponding to feeder channel, distributary channel, levee and lobe) were recognized from detailed facies analysis. Plant fragment, an important identification mark for hyperpycnal flow deposits, can be classified into three types: completely broken plant fragments, partially broken plant fragments and complete leaves. The proximal part of the deposit develops a small amount of scattered and completely broken plant fragments in massive or spaced stratified pebbly sandstone and massive sandstone due to strong erosion of sustained high‐density turbidity current. The medial part of the deposit is dominated by laminated partially broken plant fragments in planar laminated or rippled sandstone due to suspended settling of sustained high‐density turbidity current and quasi‐steady low‐density turbidity current. Layered partially broken plant fragments with some complete leaves are common in the upper part mud rich division of hybrid event bed and laminated siltstone in the distal part of the deposit. The distribution pattern of hyperpycnites is controlled comprehensively by palaeogeomorphy and sediment supply. Palaeogullies determine the provenance direction of hyperpycnal flow. The formation of synsedimentary faults and troughs control the transport routing patterns. Local micro‐palaeogeomorphy and depression areas further restrict the distribution of sand bodies. During the early stage of deposition with insufficient sediment supply, sediments are transported to the deep basin along confined faulted troughs forming elongated sandy bodies. During the late stage of deposition with sufficient sediment supply, sediments are transported to the deep basin without confinement accumulating fan‐shaped sandy bodies. This study offers insight for enhancing the recognition criteria of hyperpycnites, as well as their depositional model in lacustrine basins. [ABSTRACT FROM AUTHOR]

Soil erosion poses a global threat to arable land and its sustainability, particularly in China, where the most severe soil erosion exists worldwide. No-tillage (NT) and mulching (NTS) are considered the most effective soil management techniques for reducing erosion, but only 10% of the global area utilizes them. Therefore, in comparison to conventional tillage (CT), we conducted a comprehensive national assessment of NT and NTS to evaluate their impact on water erosion across China's croplands for the period spanning 2000 to 2018, through using Revised Universal Soil Loss Equation (RUSLE); subsequently, we projected the temporal and spatial erosion distribution, and examined their effects of various underlying driving factors by using a random-forest model. Nationally, the average soil loss rates were 1085, 564, and 396 t km−2 a−1 for the CT, NT, and NTS, respectively, across the entire arable land over a span of 18 years. This represents a reduction of 48% and 64% in the NT and NTS, respectively, compared to CT. From 2000 to 2018, water erosion-induced soil loss exhibited a slightly increasing trend with a wavelike pattern in CT, NT, and NTS. The spatial distribution of water erosion in China's arable land was primarily influenced by local precipitation, accounting for 45% to 52% of the total impact on CT, NT, and NTS. Additionally, the soil slope degree played a role, contributing 29% to 36% of the erosion patterns. Overall, NT and NTS demonstrated superior performance in mitigating the soil erosion in the southern regions of China, including the Central South, Southwest, and East China, owing to the substantial local rainfall and steep terrain. In contrast, NT and NTS exhibited a lower but still significant reduction in soil loss in the northern regions of China due to the flat topography and limited rainfall. However, considering the trade-off between economic losses (yield) and ecosystem benefits (erosion control), we recommend implementing NT and NTS primarily in the northern parts of China, such as the Northeast, North China, and Northwest. [ABSTRACT FROM AUTHOR]

The evolution of subaqueous deltas in mountain rivers is highly sensitive to variations in sediment load and hydrodynamic conditions, and human activities can rapidly alter these parameters. To better understand the evolution of the subaqueous Minjiang River Delta (MRD) under human activities, we investigated the effects of construction of reservoirs, channel training walls, land reclamation activities, and sand mining from 1910 to 2010. Analysis of bathymetric and fluvial discharge data revealed that the MRD shoals generally experienced slight development during the study period, but with alternating stages of erosion and deposition that were related closely to sediment discharge and the role of human activities. The northern MRD was more strongly affected by decreasing sediment load, while the southern MRD was more influenced by land reclamation. Human activities in the MRD can be divided into five stages: Weak (before 1935), blockage (1935–1950), slight strong (1950–1970), strong (1970–2000), and stable (since 2000). Correspondingly, the geomorphic evolution of the MRD can also be divided into five stages: Natural evolution, channel blockage, southern channel erosion, divergence, and degradation. Furthermore, the morphodynamic response time of MRD to a decrease in riverine sediment was found to be less than 10 years, which is much faster than the morphodynamic changes observed in large‐scale estuaries and deltas. These results provide further insight into interpreting morphodynamic changes in typical small/medium‐sized estuaries and deltas under various human activities. [ABSTRACT FROM AUTHOR]

Benggang is an erosional landform that forms in granite hills due to coupled hydraulic and gravity erosion, and its unique development makes it difficult to obtain moisture characteristics through direct means. In this study, the soil moisture characteristics were investigated on the collapsing walls with different weathering degrees of two different Benggang types defined as scoop‐shaped Benggang and strip‐shaped Benggang in the typical Benggang erosion areas of southeastern Guangxi. The soil water characteristic curves (SWCCs) of the collapsing wall were measured by the centrifuge method to explore the moisture transport mechanism of Benggang development. The response of moisture characteristics to the Benggang morphology was not significant, but the soil layer changes in the collapsing wall had a significant impact. The Atterberg limits of the surface layer and laterite layer were significantly higher than those of the transition layer and sandy layer, with a liquid limit (LL) value exceeding 55%, indicating high LL clay. The Van Genuchten (VG), Gardner and Fredlund–Xing (FX) models were used to fit the SWCCs, and the results indicated that the VG model had a high fitting accuracy (R2 > 0.984), followed by the FX model (R2 > 0.943); however, the Gardner model had a low fitting accuracy (R2 > 0.891). With the change in matrix suction, the sandy layer had the maximum water release capacity, followed by the transition layer, and finally the surface layer and laterite layer. The variation in equivalent pore size distributions with soil layers showed that the micropores in the laterite layer of the two Benggangs accounted for 44.91% and 44.38% of the total porosity. The macropores of the sandy layer accounted for 35.40% and 36.84% of the total porosity. Both the unsaturated hydraulic conductivity K(θ) and water diffusivity D(θ) exhibited two abrupt changes with increasing soil volumetric water content, and K(θ) and D(θ) of the lower layers were larger than those of the upper layers. The heterogeneity of soil texture and pore conditions among different collapsing wall soil layers can significantly affect the Benggang water conditions. This study provides a database for further investigation of the Benggang development mechanism. [ABSTRACT FROM AUTHOR]

Tunnel projects in the southwestern mountainous area of China are in full swing. According to the tunnel burial depth, structural characteristics, and chemical erosion environments of the Lixiang railway tunnel, carbonaceous slate specimens obtained in the field were taken to experimentally investigate the physical, mechanical, and creep characteristics of the bedding's slate specimens after chemical erosion. The results of scanning electron microscopy (SEM) indicate that chemical erosion leads to internal damage in the carbonaceous slate specimens, and the internal damages are increasing with the increase of erosion days. Moreover, the specimens' ultrasonic test (UT) results prove that specimens with smaller bedding angles suffer a more serious erosion and induce more internal cracks. Under conventional triaxial compression conditions with 40 MPa of confining pressures, the conventional triaxial compressive strength (σs) decreases with the decrease of the bedding angle and the increase of erosion days, and the failure modes of the specimens are mainly controlled by oblique shear fractures and accompanied by the occurrence of slip dislocation fractures between the bedding inclination. Under creep conditions with 40 MPa of confining pressures, the final deformations of specimens are increasing with the increase of erosion days, which means the longer the erosion days, the greater the deformations. The failure modes of the specimens under creep conditions are controlled by shear fractures, and for the specimen with a 60° bedding angle and long-term erosion, there are block separations and many cavities along the shear planes. Therefore, more attention should be paid to prevent serious failure of the surrounding rock if the surrounding rock has a bedding angle of 60° or suffers long-term erosion. [ABSTRACT FROM AUTHOR]

Gully erosion is widespread in central China's ecologically fragile loess plateau. However, research on the monitoring and evaluation of large-scale erosion is scarce. Here, we collected 16 pairs of Sentinel-1A images from the rainy season, spanning April 5-October 26, 2019, subsidence is then quantified and its results can indirectly reflect the intensity of erosion on the largest loess plateau in China, the Dongzhiyuan tableland, using small baseline subset synthetic aperture radar interferometry (SBAS-InSAR). The results showed that, the average erosion rate was 9 mm/year, throughout the study area, Surprisingly, the average erosion rate in the gully reached 160 mm/year, the sides of the gully correspond to the most extensive and intense erosion. Heavy rainfall, slope gradients below 15°, changes in groundwater levels due to freeze–thaw action and water infiltration during rainfall, and lack of vegetation due to continued gully side erosion, drive the intense erosion. These results demonstrate the reliable ability of the SBAS-InSAR method in accurately assessing large-scale gully erosion. The InSAR-calculated subsidence demonstrates a strong predictive capability for soil erosion and is generally consistent with previously observed levels of erosion, although much noise interference also occurs. Therefore, in the future InSAR-calculated sedimentation could be used as an indirect measure of erosion levels at multiple watershed scales. [ABSTRACT FROM AUTHOR]

Extreme weather events and anthropogenic activity have severely impacted the Minjiang estuary (MJE) with evolution patterns in recent decades. Determining the estuarine alluvial evolution pattern is crucial for the sustainable development of densely populated coastal areas. Using chart data, this paper analyzed how the MJE's flushing and siltation changed over time (1950–2019). The findings indicate that, in the past 70 years, the MJE has evolved through seven stages of flushing and siltation under the condition of decreasing incoming sediment: "significant siltation - siltation - minor siltation - significant erosion - significant siltation - minor siltation - significant erosion". Despite decreased incoming material, the estuary underwent substantial siltation from 1998 to 2005. Extreme meteorological conditions were the cause of this anomaly. The "severe flushing" phenomenon occurred in the study area from 2011 to 2019, and the comparison of pre-dam and post-dam at the estuary revealed that extreme weather can only adjust in stages and cannot change the overall state of the estuary flushing due to the reduction of incoming sediment in the basin. According to the EOF (Empirical Orthogonal/Eigen Function) study of four sections of the estuary, it is most impacted by incoming sediment from the watershed, followed by severe weather conditions. Our research is crucial for comprehending how human behavior and harsh weather might affect the development of MJE, and it offers sound advice for the long-term management of MJE. [ABSTRACT FROM AUTHOR]

Rapid permafrost thawing triggered by heat release from the buried warm-oil pipeline would result in the instability of the pipeline, posing a potential risk of an oil spill in permafrost regions. Therefore, how to precisely control the ground temperature to mitigate pipeline foundation permafrost from thawing is of significant importance. Thermosyphon is a widely-accepted and extensively-used countermeasure against permafrost thawing in permafrost engineering. This paper presents 3-year (2015–2018) monitored data of ground temperature and geophysical survey results conducted by electrical resistivity tomography in April 2018, to investigate the thermal stabilizing effect of thermosyphons installed nearby the China-Russia crude oil pipeline (CRCOP) and the influencing factors. Furthermore, numerical simulation tests were conducted to evaluate their long-term cooling applicability and to optimize their layout parameters. Field observations show that the thermosyphons can cool down and even freeze the thawed soil layers around the CRCOP, prohibiting the infiltration of water into the thawing front to some extent and effectively mitigating the rapid thawing of permafrost beneath the pipeline. The performance of the thermosyphons is greatly influenced by the method and time of thermosyphon installation, as well as layout parameters including the number and longitudinal spacing. Two pairs of thermosyphons with a shorter spacing are unable to control the thawing of the underlying permafrost due to the non-anticipated higher oil temperature, the thermal erosion of water ponding, and climate warming. The simulated results indicate that thermosyphons perform well in the first 5 years after installation. Thermosyphon lowers the mean annual temperature of soils surrounding it by about 2 and 1.4 times when the evaporator section length is increased by 50% and the longitudinal spacing is decreased by 0.5 m, respectively. The application of thermosyphons has proven its strength for thermally stabilizing the pipeline foundation permafrost along the CRCOP. • 3-year ground temperature data and geophysical survey results are presented. • Thermosyphon can mitigate the rapid thawing of permafrost beneath the pipeline. • Thermosyphons performs most significantly in the first five years. • Lengthening thermosyphon and decreasing spacings are favorable for the better cooling effect. [ABSTRACT FROM AUTHOR]

Rill erosion on unpaved roads is widespread and highly destructive on the Loess Plateau of China, but the exploration of its evolution mechanism is scarce. In this study, a multiphase runoff scour experiment was performed on an abandoned field road in the Loess Plateau, China. Using a terrestrial laser scanner (TLS), scour experiments are used to evaluate the dynamic evolution of rill erosion and fill. The results show that soil erosion decreases significantly after the initial surge. During the first scouring, the depths of erosion and fill reached their maximum, which were 5.49 ± 7.62 mm and 5.72 ± 16.37 mm, respectively, and the fourth erosion and fill rates are only 24% and 35% of the first. Unlike the upstream and midstream, which are dominated by erosion, the downstream is mainly characterized by fill, and the downstream fill depth is 1.46 times the erosion depth; however, this ratio is 0.52 and 0.74 in the upstream and midstream, respectively. A comparison of the erosion raster with slope change revealed that rapid slope change due to erosion was mainly concentrated at 10–15°. In addition, a comparison of the fill raster with the slope found that slopes greater than 30° during the second scouring tended to flatten out most by filling, as the hydrodynamic forces of steep slopes were easily dissipated. The relationship between slope, erosion, and fill is complex and variable for each scouring. Orthophotos revealed that the U‐shaped bottom topography was conducive to concentrated overland flow, which significantly worsens the rill erosion on the road surface. This indicates that even if the slope is very gentle, the terrain easy to collect water will cause considerable erosion damage. Prevention of rill erosion on the unpaved loess road surface, therefore, requires focused drainage development. This study provides important further scientific insights into the evolution of loess road rill erosion and road erosion damage to inform erosion hazard management in the context of fragile loess landscapes. [ABSTRACT FROM AUTHOR]

The Sulu ultrahigh-pressure (UHP) belt has been proven to form by deep northward subduction of the Yangtze Block (YB) beneath the North China Block (NCB) in the Triassic. The basement rocks originated from the YB and experienced Triassic UHP metamorphism. In this contribution, we identify for the first time tens of non-UHP metasedimentary blocks enclosed in the regional UHP granitic gneiss in the Weihai terrane in the northeastern Sulu UHP belt. They are mainly composed of paragneiss, marble and calc-silicate rocks, in which UHP-related minerals have not been identified. Detrital zircons from the non-UHP metasedimentary rocks are mostly of magmatic origin and yield U-Pb ages mainly from 2842 to 1792 Ma with two clusters of 2580–2460 Ma and 1900–1800 Ma. This zircon U-Pb age spectrum is typical of the NCB but not the YB, and matches the tectonothermal/magmatic history of the southwestern end of the Jiao-Liao-Ji belt (JLJB), eastern NCB, which lies immediately adjacent to the Weihai terrane. Furthermore, their whole-rock geochemical compositions show great resemblance to those of the Paleoproterozoic metasedimentary rocks within the JLJB. In particular, metamorphic zircons from the non-UHP metasedimentary rocks indicate widespread late Triassic-early Jurassic (213–194 Ma) metamorphic overprinting of the Paleoproterozoic (1850–1820 Ma) metamorphism that characterizes the JLJB. This means that the enclosed non-UHP metasedimentary rocks with NCB signatures in the Weihai terrane were involved in the collision-subduction process during the Triassic. They have not been carried to mantle depths during deep continental subduction. These lines of evidence prompt us to establish a Triassic tectonic erosion model to explain these new discoveries and pre-existing problems along the Sulu UHP orogenic belt. [ABSTRACT FROM AUTHOR]