Types Of Erosion Research Articles

Formation of Gully Erosion in the Myjava Region

Abstract The article deals with the problems of the occurrence and formation of gully erosion in the Myjava catchment. Gully erosion is a significant problem in that region of Slovakia. Together with this type of soil erosion, muddy floods, waste ground, economic losses in agriculture, and many other problems are involved. The main objectives of this article are an analysis of the occurrence of gully erosion in the Myjava region in different periods of time and identification of the most significant factors that have impacted the formation of the gully network. The appearance of gully erosion has been identified from historical maps and other historical documents preserved from the region. The factors analysed were mainly human activities that resulted in changes in land use and physical-geographic catchment characteristics such as the soil, the geology, and the morphology. Nowadays, we are seriously lagging behind in dealing with this issue compared to other European countries.

Establishment and Application of Ecological Suitability Evaluation System for Highway Route Selection of Subtropical Mountains

Subtropical mountains area Landsat8 satellite Tm images were used as information sources, RS technology was used to extract vegetation coverage, soil erosion and land use type for the evaluation of ecological background condition, and the GIS software was utilized to extract indices of terrain slope and water environment. Based on the indicators above, with GIS analysis techniques, comprehensive evaluation and analysis of the ecological background the subtropical mountains area were conducted, subtropical mountains ecological background conditions could be classified as excellent, good, fair, poor and very poor level. Based on the overall distribution and evaluation route corridors with relatively some feasible routes, and possible route options were compared to ultimately determine the best route with environmental coordination. The results show that the method overcomes the limitations of traditional line selection method which is too dependent on designers experience and subjective judgement.

Mesh erosion after hiatal hernia repair: the tip of the iceberg?

Primary repair of large hiatal hernia is associated with a high recurrence rate, which has led to the use of mesh for crural repair. However, severe mesh-related complications, including esophageal or gastric erosion, have been observed. In the present study, we made a thorough identification of all published reports on the esophageal or gastric mesh erosion or migration after hiatal hernia repair. The incidence, site, mesh type, latent interval, consequence and treatment methods of mesh erosion were summarized and analyzed. A total of 50 cases of esophageal or gastric mesh erosion or migration after hiatal hernia repair were reported since 1998. A higher erosion rate was observed in recurrent hiatal hernia repair. The most common erosion site was esophagus (50%), followed by stomach (25%) and gastric-esophageal junction (GEJ) (23%). The most common mesh types reported in this series were PTEF andpolypropylene. The duration from the hernia repair to the identification of erosion varied greatly, and 79% of the erosion occurred within 2years after the hernia repair. Various treatment methods were reported, including endoscopic mesh retrieval (15.7%), laparoscopic mesh removal (11.8%), surgical mesh removal (19.6%); however, distal esophageal resection and gastric resection were reported in 19.6% and 5.9%, respectively. Some patients had to receive tube feeding. The true incidence of mesh erosion after hiatal hernia repair may be higher than previously reported, and the erosion is more prone to occur after recurrent hiatal hernia repair. Mesh erosion can result in severe morbidity and sometimes require complex organ resection. Different kinds and shapes of prosthetic meshes can cause erosion; therefore, mesh should be used very selectively for hiatal hernia repair. The patient should be informed about the mesh placement and the possible mesh-related complications.

Automated system for soil wind erosion studies

Wind erosion is a natural soil degradation process that threatens agriculture in many locations. We have used several different methods, including wind tunnels, to analyze this type of soil erosion. In this paper we present a new wind tunnel design that enables very simple analysis of soil wind erosion. The equipment is lightweight and can be folded up for easier transport. This very easy-to-install prototype combines laser telemetry, computer vision, and sediment collection analytical techniques. Tests can be done more quickly, so manifold areas can be covered in a short time. The innovative use of sensors allows the experiments to be replicated the same way anywhere, so different experiments can be easily compared. This wind tunnel is designed to be used in any terrain and has an automatic data collection and analysis system.

Coastal Processes and Influence on Damage to Urban Structures during Hurricane Irma (St-Martin & St-Barthélemy, French West Indies)

This study aims to better understand coastal processes associated with extreme cyclonic events through the study of the coastal changes, flooding and damage that resulted from the passage of a category 5 hurricane (Irma) on 6 September 2017 over the islands of Saint-Martin and Saint-Barthélemy in the Lesser Antilles. Hurricane Irma was contextualized from tropical cyclone track data and local weather observations collected by Météo-France, as well as high-resolution numerical modelling. Field work involved the study of accretion coasts through qualitative observations, topo-morphological and sedimentary surveys, as well as image acquisition with Unmanned Aerial Vehicle (UAV) surveys during two trips that were made 2 and 8 months after the catastrophe. Wave propagation and flood numerical models are presented and compared to field data. Our field analysis also reports on the devastating impacts of storm surges and waves, which reached 4 and 10 meters height, respectively, especially along east-facing shores. The approaches reveal a variety of morpho-sedimentary responses over both natural and highly urbanized coasts. The analysis shows the effects of coastal structures and streets on flow channeling, on the amplification of some erosion types, and on water level increase. Positive spatial correlation is found between damage intensity and marine flood depth. The signatures of ocean-induced damage are clear and tend to validate the relevance of the intensity scale used in this study.

Research on Visual Interpretation and Spatial Distribution Pattern of the Erosion Gully in Luoyugou Watershed of China

There are criss-cross Ravines and gullies in the Loess Plateau, where the erosion gullies grows better. The loess material, which is loose and has the vertical jointing, is easy to suffer from the erosion; the types of erosion in this area mainly include gravitational erosion and the trench erosion. There are typical gulling erosion in Luoyugou watershed of Tianshui northern suburb, located in the interactive region of Longxi Loess plateau hill-gully area and the Longnan mountainous area. Under the support of the SPOT satellite photos in 2008 and field survey, the paper establishes the visual interpretation features of erosion gully, extracting the information of erosion gully, and uses the landscape pattern analytical method, studying the spatial distribution pattern of the erosion gully in the watershed. Finally, the paper draws the following conclusions: 1) The shapes of erosion gullies are strip or arborization, and in the black-white image, the stable erosion gullies appear deep dark color, active erosion gullies present the bright color, and half-active erosion gullies are the shallow dark color; while in color synthesis image, the color of stable erosion gullies mixes garnet, and other erosion gullies are bright green. 2) There are more erosion gullies in the study area where human activities occur frequently, such as the both sides of terraced field, the side of road and the river marshland, the both sides of terraced field have. 3) The erosion gullies in the study watershed are primarily stable ones, whose area accounts for 51.3% of the total erosion gullies, and half-active ones accounts for 18.3%. This phenomenon indicates the progress in the control of the erosion gullies in this basin. 4) From the upstream to the downstream in the research basin, the erosion gully's average shape index has the tendency to reduce gradually, illustrating that the more getting nearly to the downstream, the more the slope of erosion gully to be gentler. The data results match well with the actual terrain feature.

Spatial prediction of landslide susceptibility in Taleghan basin, Iran

Identifying landslide-susceptible zones is warranted to prevent and mitigate associated hazards in mountainous regions, where a landslide is a destructive type of erosion. A landslide susceptibility map was developed for the Taleghan basin based on frequency ratio (FR), logistic regression (LR), maximum entropy (MaxEnt), and support vector machine (SVM) with radial base (RBF), sigmoid (SIG), linear (LN), and polynomial (PL) kernel functions. To this end, an inventory map with 166 landslide locations was prepared and partitioned into 70% and 30% to train and validate the models, respectively. Subsequently, the models were designed based on 13 factors including elevation, slope degree, slope aspect, distance to stream, Stream Power Index, Topographic Wetness Index, Stream Transport Index, distance to fault, lithology, soil texture, land use, distance to road and precipitation. The performance of the methods was assessed using the area under the receiver operating characteristic curve, the Seed Cell Area Index (SCAI), the precision index (P). Moreover, statistical measures including sensitivity, specificity, and accuracy were calculated. Friedman test was also applied to confirm significant statistical differences among the seven models employed in this research. The validation results showed that MaxEnt had the maximum area under the curve (0.812). The results obtained using the models LR, FR, PL-SVM, SIG-SVM, LN-SVM, and RBF-SVM were 0.807, 0.732, 0.679, 0.663, 0.643 and 0.660, respectively. The obtained P index showed the better performance of MaxEnt and LR models. Moreover, the trend of changes in the SCAI values, from low- to high-susceptibility, indicated that the MaxEnt and LR models had the best performance. Decision makers can effectively use the findings of the present study to mitigate the financial and human costs resulting from the landslides.

Land degradation index of tropical forest landscape in Batang Toru watershed using spatial analysis

Forest degradation and deforestation have reduced the functions of forest ecosystem in Batang Toru watershed landscape. The degree of land degradation rate can be minimized by restoring the functions of forest ecosystem. Data concerning the degree of land degradation is needed to restore the functions of forest ecosystem. This research aims to obtain spatial distribution characteristics of land as well as land degradation index in Batang Toru watershed landscape. Land degradation was determined by using 3 variables, namely soil chemical and physical properties, as well as erosion type which occur in the site. Each variable was ranked through Likert scale. The total score of all land degradation indicators was converted into land degradation index. The study found that land degradation index in Batang Toru watershed landscape consist of very low (0,00-0,2), low (0.21-0,4), moderate (0.41-0,60 ), high (0.61-0.80) and very high (0.81-1.00). Most of Batang Toru watershed areas fall into moderate land degradation category.

Democracy, Federalism, and the Guarantee Clause

The Guarantee Clause of the Constitution promises that “[t]he United States shall guarantee to every State in this Union a Republican form of Government . . . .” The Supreme Court has long held this Clause to be nonjusticiable, and as a result, many see the Clause as purely vestigial. But nonjusticiable does not mean toothless, and this view fails to recognize the Clause’s grant of power to Congress. The Guarantee Clause provides Congress with the authority to ensure that each state’s internal governance meets a minimum standard of republicanism. The Framers included this promise because they feared that some forms of government, such as monarchy, were incompatible with republicanism, which they understood as representative self-government. Nonrepublican government in one state, they believed, might have deleterious or even dangerous effects on other states, and protection against nonrepublican government was thus essential for long-lasting and healthy interstate and federal–state relationships. Today, the Framers’ fears appear prescient as a number of states engage in tactics like extreme partisan gerrymandering, which entrenches one party in power; lame-duck legislation, which reallocates power to undermine an incoming administration; and targeted burdens on voting. These tactics parallel the types of democratic erosion that scholars have observed internationally and historically. Moreover, the potential negative effects of these antidemocratic tactics from one state to another, and from one state to the nation as a whole, are substantial and threaten to undermine many of the benefits of federalism. Fortunately, the Guarantee Clause allows—indeed, requires— Congress to address these antidemocratic state-level practices.

The reverse shoulder arthroplasty angle: a new measurement of glenoid inclination for reverse shoulder arthroplasty

Avoiding superior inclination of the glenoid component in reverse shoulder arthroplasty (RSA) is crucial. We hypothesized that superior inclination was underestimated in RSA. Our purpose was to describe and assess a new measurement of inclination for the inferior portion of the glenoid (where the baseplate rests). The study included 47 shoulders with rotator cuff tear arthropathy(mean age, 76 years). The reverse shoulder arthroplasty angle (RSA angle), defined as the angle between the inferior part of the glenoid fossa and the perpendicular to the floor of the supraspinatus, was compared with the global glenoid inclination (β angle or total shoulder arthroplasty [TSA] angle). Measurements were madeon plain anteroposterior radiographs and reformatted 2-dimensional (2D) computed tomography (CT) scans by 3 independent observers and compared with 3-dimensional (3D) software (Glenosys) measurements. The mean RSA angle was 25° ± 8° on plain radiographs, 20° ± 6° on reformatted 2D CT scans, and 21° ± 5° via 3D reconstruction software. The mean TSA angle was on average 10° ± 5° lower than the mean RSA angle (P < .001); this difference was observed regardless of the method of measurement (radiographs, 2D CT, or 3D CT)and type of glenoid erosion according to Favard. In Favard type E1 glenoids with central concentric erosion, the difference between the 2 angles was 12° ± 4° (P < .001). The same angle cannot be used to measure glenoid inclination in anatomic and reverse prostheses. The TSA (or β) angle underestimates the superior orientation of the reverse baseplate in RSA. The RSA angle (20° ± 5°) needs to be corrected to achieve neutral inclination of the baseplate (RSA angle = 0°). Surgeons should be aware that E1 glenoids (with central erosion) are at risk for baseplate superior tilt if the RSA angle is not corrected.

Sediment delivery of partially-unfrozen loam soil rill by snow/glacier meltwater flow

Erosion of freeze-thaw soil by meltwater from snow/glacier is one of the main erosion types in high altitude or latitude regions. This study aims to experimentally measure soil erosion processes over partially-unfrozen soil slopes in laboratory. The experiments including three slope gradients of 10°, 15°, and 20°, three water flow rates of 1, 2, and 4 L/min (0.06, 0.12, and 0.24 m3/h), and three thawed-soil depths of 1, 2, and 5 cm were conducted to measure sediment concentration and calculate its delivery rate under seven slope lengths of 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, and 6.0 m. The sediment delivery rates from nonfrozen soil slopes under the corresponding slope gradients, flow rates, and slope lengths also were measured as control treatments. Results showed that the sediment delivery rate from both partially-unfrozen and nonfrozen soil slopes increased logarithmically with slope length. The sediment delivery rate from partially-unfrozen soil slope increased with the increased slope gradient and meltwater flow rate significantly, and the effect of water flow rate on it was greater than that of slope gradient. The thawed-soil depth did not significantly affect sediment delivery rate. The sediment delivery rate from a partially-unfrozen loamy soil slope averagely was 11.4% smaller than that from nonfrozen soil slope. This study is helpful to understand the erosion process of thawing-soil by meltwater from snow/glacier.

Endoscopic features of submucosal invasion in undifferentiated type early gastric cancer sized less than 2 cm without ulceration.

76 Background: The prediction of invasion depth is important to decide the treatment modality for the undifferentiated type early gastric cancer (EGC) when size is less than 2 cm and had no ulceration. We aimed to identify the endoscopic features associated with submucosal invasion in the undifferentiated type EGC that meet the criteria of size and status of ulcer in the endoscopic submucosal dissection (ESD). Methods: A total of 120 patients with undifferentiated type EGC who received ESD or operation from August 2008 to December 2017 were enrolled in this study. All lesions met the ESD criteria except the invasion depth. We retrospectively reviewed endoscopic features of tumor before the resection and depth of invasion after resection. Results: In 120 undifferentiated EGCs, the mucosal and submucosal cancer were 97 and 23 lesions, respectively, In univariable analysis, discolor change, upper third location, the presence of deep/wide erosion were associated with submucosal invasion. Multivariable analysis revealed that upper/middle third location (odds ratio [OR] 8.0, 95% confidence interval [CI] 1.2-55.0; OR 7.9, 95% CI 1.8-35.1), erosion or polypoid (OR 41.8, 95% CI 4.1-427.9), and elevated type (OR 20.9, 95% CI 2.5-173.8) were significant risk factors. In 112 patients received gastrectomy with lymph nodes dissection, lymph node metastases were found in four cases (three mucosal cancer and one submucosal cancer). However, there was no lymph node metastasis in the lesions meeting the expanded ESD indication. Conclusions: The careful decision of treatment modality is needed for undifferentiated type EGC with erosion or elevated gross type located on the upper/middle third, although the tumor size and ulcer status meet the ESD indication.

Research progress on the effects of freeze-thaw on soil physical and chemical properties and wind and water erosion

Freeze-thaw erosion, one of the main types of soil erosion, is widely distributed in China. The distribution and harm of the combined erosion of freeze-thaw and other forces were greater than freeze-thaw erosion. We reviewed related research progress of the effects of freeze-thaw on soil phy-sical and chemical properties, wind erosion, and water erosion, based on literatures from China and abroad. Under the condition of freeze-thaw, soil water was transported and soil structure was dama-ged. Soil porosity, bulk density, shear strength, aggregate stability and organic matter were all changed. The change tendency and amplitude were related to soil texture and the degree of freeze-thaw. The occurrence and process of soil wind erosion and water erosion were influenced by the condition of freeze-thaw. Soil erodibility and erosion intensity increased as a result of the changes of soil physical and chemical properties. At present, the research on freeze-thaw mainly based on indoor simulation, which was quite different from the actual freeze-thaw process in the field. The conclusions obtained were not unified or even contrary due to different test conditions. Therefore, through combining indoor simulation and field survey, to strengthen the research of soil erosion mechanism of freeze-thaw conditions was the focus of the future research, which was of great significance for forecasting and preventing of soil erosion in the periods of thawing and the regions of seasonal freeze-thaw.

Assessment of the importance of gully erosion effective factors using Boruta algorithm and its spatial modeling and mapping using three machine learning algorithms

The Maharloo watershed has witnessed many gullies in the recent due to the specific topo-climatic conditions and man-made activities in that area. The present study is set out to address this issue by producing gully erosion prediction maps via three machine learning algorithms including RF, SVM and BRT in Maharloo watershed, Fars province, Iran. Also, this research attempted to consider the importance of effective factors in the occurrence of gully erosion using Boruta algorithm. To this end, gully erosion locations were identified by extensive field surveys as well as the use of already prepared gully raster map of Maharloo watershed. Then, sixteen causative factors of gully erosion such as elevation, slope degree, slope aspect, plan curvature, TWI, distance from rivers, distance from roads, drainage density, lithology, annual mean rainfall, NDVI, land use and some soil characteristics (pH, clay percent, electrical conductivity-EC, and silt percent) were identified and their maps were produced and classified in the GIS. In this study, the relationships among each agent and gully erosion were defined employing the evidential belief function (EBF) algorithm and the weight of each factor's classes was determined. On the other hand, the results of the collinearity test among the factors showed that sand percentage agent had a VIF > 5; therefore, this covariate was removed from the model. Also, the results of the importance of effective factors using Boruta algorithm indicated that three factors including land use, distance from river, and clay percent had the most noticeable importance in the occurrence of gully erosion in the study area. Finally, the gully erosion susceptibility maps were produced using the RF, BRT, and SVM models in the R statistical software. The results of machine learning techniques were evaluated employing 30% of unused locations in the modeling process as well as the receiver operating characteristic (ROC) curve. Also, in the current research, try to assess the fitting performance of models and their robustness using sensitivity rate, specificity rate, Cohen's Kappa, and 4-fold cross-validation measures. Results showed that the final gully erosion susceptibility maps had an excellent accuracy with AUC values of validation data sets by scenarios 7 and 9 independent factors on gully erosion, respectively (SVM = 0.957, 0.975, RF = 0.991, 0.986, BRT = 0.913, 0.913). The fitting performance measures and robustness technique (4-fold cross-validation) also confirmed the achieved validation results. In order to control and prevent this type of erosion in the Maharloo watershed, there should be protective actions and watershed management measures in place at the primary stages, especially at the beginning of the gully erosion, to control the development of the gully erosion.

Test of the RUSLE and Key Influencing Factors Using GIS and Probability Methods: A Case Study in Nanling National Nature Reserve, South China

The main purposes of the study were to test the performance of the Revised Universal Soil Loss Equation (RUSLE) and to understand the key factors responsible for generating soil erosion in the Nanling National Nature Reserve (NNNR), South China, where soil erosion has become a very serious ecological and environmental problem. By combining the RUSLE and geographic information system (GIS) data, we first produced a map of soil erosion risk at 30 m‐resolution pixel level with predicted factors. We then used consecutive Landsat 8 satellite images to obtain the spatial distribution of four types of soil erosion and carried out ground truth checking of the RUSLE. On this basis, we innovatively developed a probability model to explore the relationship between four types of soil erosion and the key influencing factors, identify high erosion area, and analyze the reason for the differences derived from the RUSLE. The results showed that the overall accuracy of image interpretation was acceptable, which could be used to represent the currently actual spatial distribution of soil erosion. Ground truth checking indicated some differences between the spatial distribution and class of soil erosion derived from the RUSLE and the actual situation. The performance of the RUSLE was unsatisfactory, producing differences and even some errors when used to estimate the ecological risks posed by soil erosion within the NNNR. We finally produced a probability table revealing the degree of influence of each factor on different types of soil erosion and quantitatively elucidated the reason for generating these differences. We suggested that soil erosion type and the key influencing factors should be identified prior to soil erosion risk assessment in a region.

Quaternary Glaciotectonics of the Ural-Siberian North

Abstract This is a review of previous works on glaciotectonics and recent epeirogenesis of the northern West Siberian sedimentary basin and adjacent parts of the Urals and the Siberian Craton. It is supported by the addition of detailed structural profiles of the disharmonic dislocations around Malyi Atlym settlement on the Lower Ob’ never published before. The collected data highlight sources and results of neotectonic phenomena in the north of West Siberia and their impact on distribution of hydrocarbon deposits. The rugged topography of the northern Urals and Mid-Siberian Plateau, discordant with the regional tectonic structure, is generated by compensation uplifts along the margins of thick ice sheets in the West Siberian North. Ice load vacillations were an important factor of geographical separation of hydrocarbons liquid and gaseous phases. This is evident from the west–east zonation of petroleum deposits, discordant with the south–north strike of ancient structures but concordant with thickness zonation of ice sheets. The structure of the alpine-type dislocations penetrating up to 400 m into the sedimentary basin on the Lower Ob’ reveals that the variations of their tectonic style do not fit the mechanical properties of thawed Paleogene rocks. However, they are more understandable assuming their origin from deviatoric stress in pressurized perennially frozen Paleogene rocks. Such conditions are feasible at the base of a growing thick ice sheet. Ice sheets did significant work of glaciotectonic erosion of soft Paleogene rocks of the perennially frozen substrate soldered with glacial ice. This type of erosion is evident in the Ob’ catchment area where whole blocks of intact sand and clay were transported by glaciers over hundreds of kilometers. Glaciotectonic erosion of glacier substrate is sufficient for explaining the well-known stratigraphic hiatus between Quaternary and Upper Cretaceous formations of the Siberian Arctic instead of the popular but illogical tectonic inversion of the sedimentary basin.

Empirical Analysis of Farmers’ Perception on Causes, Variability and Control Measures of Soil Erosion on Different Lands in Yola and Environs of Nigeria

Soil erosion is one of the most devastating phenomena affecting soil resources and food availability in Yola and environs. However, Farmers’ perceptions on the causes, variability and control measures to conserve natural soil resources have receivedlittle emphasis in the study area. Therefore, this study aimed to understand farmers’ perception on causes, the variability of soilerosion and their indigenous methods adopted in soil erosion control. The study was conducted in Yola where five farm locationswere purposively selected ( Yolde pate, Mbamba, Bole, Wuro-chekke and Namtari ). Data was collected using household interviews where 30 farmers were selected and interviewed from each location making a total of 150 farmers in all. It wasrevealed that water and tillage erosions were the two major types of soil erosion in the study. Similarly, heavy rainfall,deforestation and steep were the major causes of soil erosion in all the farm locations. Gully and rill-gully erosion were the mostprevalence on the farmlands and the erodibilty level was rated high to very high affecting the soil resources. For the controlmeasures, farmers in the study area have adopted majorly contour ridging, planting of vegetative barriers and waters ways incontrolling the erosion on their farmlands. The study recommends the establishment of erosion control scheme by the government in the area and farmers should be trained adequately on modern techniques of controlling erosion with respect to its causes and erodibilty level for optimum food production that will meet up the accelerated growing population in the area and beyond.

Evaluation and spatial distribution characteristics of freeze-thaw erosion intensity in the Yalu Tsangpo River basin on the basis of geographic information system

Freeze-thaw erosion is one of the main ways of soil erosion in three major erosion types, which are related to the development of regional economy and the protection of ecological environment. Therefore, its research is particularly important. This paper uses the Yalu Tsangpo River basin as the research area. The range of the freeze-thaw erosion area in the Yalu Tsangpo River basin was defined by using Shuttle Radar Topography Mission-Digital Elevation Model (STRM-DEM) data. Six factors, namely, annual temperature difference, annual precipitation, slope, aspect, vegetation coverage, and elevation, were selected as the evaluation indexes of the intensity of freeze-thaw erosion. Analytic hierarchy process (AHP) was used to determine the weight of each factor. A comprehensive evaluation index model was employed to obtain the range of freeze-thaw erosion intensity. The natural breaks method in ArcGIS was applied to grade the result. The classification chart of the freeze-thaw erosion intensity of the Yalu Tsangpo River basin was drawn to show the distribution of freeze-thaw erosion. Results showed that (1) the total area of freeze-thaw erosion in the Yalu Tsangpo River basin is 229,231.80 km2, which accounts for 93.5% of the total area of the Yalu Tsangpo River basin, with mild erosion and moderate erosion. (2) The distribution of freeze-thaw erosion intensity in spatial pattern is obvious; from west to east, the intensity of freeze-thaw erosion increases gradually. Severe erosion is mainly concentrated in the northeast and northern regions of the Yalu Tsangpo River basin. (3) The areas of freeze-thaw erosion are mainly distributed in the temperature zone with the annual temperature range of ≥40 °C, accounting for 86.4% of the total freeze-thaw erosion area. The freeze-thaw erosion area is mainly distributed in the slope ≥15° slope zone, which accounts for 62% of the total freeze-thaw erosion area, and has a severe effect on moderate erosion and severe erosion in this slope zone. Freeze-thaw erosion areas are mainly concentrated in vegetation belts with vegetation coverage less than 20%, accounting for 63.8% of the total freeze-thaw erosion area. With the increase in vegetation coverage, the proportion of freeze-thaw erosion area decreased. The freeze-thaw erosion area was mainly concentrated on the altitude zone of ≥4000 m, which accounted for 84.3% of the total freeze-thaw erosion area. Thus, the freeze-thaw erosion area increased with altitude.

Effect of soil moisture on soil disintegration characteristics of different weathering profiles of collapsing gully in the hilly granitic region, South China.

Collapsing gully erosion is the main important and specific soil erosion type in the red soil region of tropical and subtropical South China. Knowledge of the soil disintegration characteristics within different weathering profiles (surface layer, red soil layer, sandy soil layer and detritus layer) and its relationships with soil particle size distribution and soil properties is important in understanding the mechanism of the forming process and development of the collapsing gully. In this paper, we conducted an experiment on four collapsing gullies located four counties (Tongcheng County, Gan County, Anxi County and Wuhua County) in the hilly granitic region of southern China. The anti-disintegration ability of the different weathering profiles with two different moisture conditions (the air-dried condition and the natural state condition) were determined by the anti-disintegration index (Kc) and measured by the submerging test. The results show that the coarse particles are higher in the sandy soil layer and the detritus layer of collapsing gully than that in the surface layer and the red soil layer, but the finer particles show the inversed order. The Kc values reduce significantly from the surface layer to the detritus layer. In the surface layer and the red soil layer, the Kc values in the natural state condition are much higher than that in the air-dried condition. The results highlight that, the sandy soil layer and the detritus layer are easily to disintegrate compare with the surface layer and the red soil layer, and in the case of low soil water content, the soil in any layer of collapsing gully is easy to disintegrate. The regression equation shows a very significant and positive relationship between the Kc values and the < 0.002 mm particles contents and the SOM (soil organic matter) (p<0.01), and negative relationship between the Kc values and the contents of other soil particle size. The results revealed that the repulsive force produced by compressed air in the soil exceeds the suction between the soil particles is the predominant factor to soil disintegrate rates in the air-dried state condition. Whereas the soil contained a certain amount of water can reduce the degree of disintegration. The results also indicated that the more contents of the cementation agents (like clay and SOM) in the soil of the different layers of collapsing gully, the higher Kc values (it means the more difficult to disintegrate).

Compositional variations of Titan's impact craters indicates active surface erosion

Titan, the only moon in the solar system with a considerable atmosphere, is host to a variety of exogenic processes that shape its surface. These processes form features that are quite similar to features on Earth, including sand dunes, rivers, and lakes. The combination of a thick atmosphere and active surface processes also leads to a scarcity of impact craters on the surface of Titan. The compositions of these craters vary and may relate to the type and extent of erosion occurring at their location. In this work, we examined the composition of 12 impact features on Titan using Cassini's Visible and Infrared Mapping Spectrometer (VIMS) and 2.18 cm emissivity data from the RADAR radiometer on board the probe. Comparisons were made between crater composition as inferred from VIMS and composition as inferred from emissivity data with corresponding crater characteristics such as latitude, longitude and erosional state. We see a correlation between crater subsurface composition as inferred from the emissivity data and its erosional state and location. Well-preserved craters typically are more enriched in water-ice than degraded, organic-rich craters, suggesting that variations in composition are partially controlled by erosion and infilling. Moreover, craters located in dune fields show more subsurface organic enrichment than craters within the plains, which indicates that the efficiency of erosion and infilling varies with location and geologic context. VIMS data provide complementary information about crater surficial composition. We note that VIMS spectra do not change with erosional state, but rather appear to depend on the crater location on the moon. We suggest that there are active surface processes occurring on Titan, such as wind or rain, which are actively clearing off its surface and filling in subsurface fractures with organic materials. These processes would act to change the emissivity of the craters over time but leave the surface sensed by VIMS unchanged.