Extent Of Erosion Research Articles

Determining Causes of Erosion and Sedimentation at Cua Dai Beach, Quang Nam Province, Vietnam: Applying an Integrated Geographical Approach

Cua Dai is one of the 21 estuaries in the Central region and is the first river mouth to the north of the South Central Coastal region. It is renowned for its beautiful beaches, which attract many tourists. Additionally, the Cua Dai River mouth area is a fishing ground for local fishermen due to its rich marine biodiversity. However, a serious issue has emerged in this area. Cua Dai Beach has been facing severe erosion for several years, threatening its natural beauty. This article employs an integrated geographical approach, utilizing two main methods: document collection (research on geology and hydrodynamics) to determine historical changes and on-site surveys (in point format) to assess the extent and current status of erosion. Information exchange with residents is also conducted to understand the situation and gather data identifying the causes of erosion and sedimentation in the Cua Dai area, part of the lower Thu Bon River system in south-central Vietnam. The results indicate that erosion and sedimentation in the research area are influenced by both natural and anthropogenic factors, with no single factor prevailing.

Land use and climate change-induced soil erosion mapping in a sub-tropical environment

One of the most important aspects of the ‘sub-tropical’ monsoon-influenced environment is the issue of ‘soil erosion’ and its related ‘land degradation’. On the other hand, the climate in this area has become quite extreme. According to this viewpoint, it is important to research a future ‘soil erosion’ scenario in front of the probable effects of climate change and land use change. For the objective of assessing the extent of soil erosion in this area, this study took into account both the USLE and the RUSLE. Compared to the USLE that has been validated, RUSLE has a comparatively greater quantitative efficiency. In RUSLE, the ‘very high’ (>20) and ‘high’ (15–20) ‘soil erosion’ zones tend to be associated with the ‘north-western, western, south-western, and southern’ regions of the river basin. The ‘soil erosion’ that will occur in the future has been estimated by taking into account the projected rainfall, land use and land cover (LULC). ‘Soil erosion’ has increased from the previous time to the projected time. Predicted R factor values for SSP 585 range from 399.92 to 493.72. In addition, a growing erosion tendency associated with increased shared socio-economic pathways (SSPs) has been found.

Impact of Land Use/Cover Changes on Soil Erosion by Wind and Water from 2000 to 2018 in the Qaidam Basin

Assessing the impact of land use and land cover change (LUCC) on soil erosion by wind and water is crucial for improving regional ecosystem services and sustainable development. In this study, the Revised Wind Erosion Equation (RWEQ) and Revised Universal Soil Loss Equation (RUSLE) were used to reveal changes in the extent of soil erosion by wind and water in the Qaidam Basin from 2000 to 2018 and the impact of LUCC on them. From 2000 to 2018, with global climate change, the areas and intensities of soil erosion by wind decreased, whereas those of soil erosion by water increased. With increased human activities, approximately 12.96% of the total area underwent conversion of the type of use: the areas of cropland, woodland, grassland, and construction land increased, whereas the areas of shrubbery, desert, and other unused land decreased. Land use/cover changes are positive to the soil erosion of water but negative to the soil erosion of wind. Among them, the changes in vegetation coverage of other unused land and grassland contributed to 83.19% of the total reduction in soil erosion by water. Converting other unused land to grassland reduced the total reductions in soil erosion by wind by 94.69%. These results indicate that the increase in vegetative cover and area of grasslands in the Qaidam Basin had a positive impact on the reduction in soil erosion. It is recommended that the arrangement of grasses, shrubs, and trees be optimized to prevent compound erosion by wind and water for protecting regional ecological environments.

Analysis of the impact of roughness coefficient changes due to land use changes on the hydraulics of the Kashafrood River

Abstract Mashhad's Kashafrood basin has been affected by land use changes, urbanization, and the development of agricultural water resources. This basin is located in the Razavi Khorasan province, Mashhad city. This research analyzes the impact of land use changes on river flow from a hydraulic point of view. For this purpose, the studied area was divided into five sub-basins and flood values were calculated using Deacon's method and different return periods for the sub-basins. In order to determine the intensity and extent of lateral erosion, two factors, the height of the terraces (H) and the amount of erosion activity (T), were measured, separated into different classes and evaluated. Also, the river was simulated under different hydraulic regimes. The results showed that the effects of erosion in more than 50% of the observation path and the 25-year discharge entered the bed area. The highest sensitivity to changes in the roughness coefficient is related to the flow surface and the width of the upper surface. Based on this, this research provides valuable information for land use management, understanding the impact of land use changes on river basins, and for decision-making by the executives.

Analysis of land use/land cover change and erosion hazard levels in the social forestry area of KPH Ulubila, South Sulawesi Indonesia

Changes in land use/land cover are part of the dynamics of nature, both changes caused by natural disasters and human activities. The need for land by humans encourages the acceleration of land cover change, especially from forests to non-forests. The rate of change in land cover will affect the hydrological state so that the land becomes very critical. One of the things that causes land to become critical is erosion. One of the policies carried out to reduce the rate of change in land cover, reduction of erosion area and empowerment of communities around forests is the Social Forestry program. Social forestry refers to any forest utilization activity by the community in providing products for their own use or generating local income. The case study in this study is the social forestry of KPH Ulubila. The results of the analysis in 2013 and 2022 showed that the highest decline in the agricultural/crop land class with an area of 87.96 ha or equivalent to 89.20% and secondary second forest was 681.86 ha or equivalent to 27.50% of the area of social forestry. In other classes, there was an increase in agricultural land, namely in the plantation class of 267.83 ha or 467.19%, agricultural mixed of 160.73 ha or 7.20% and paddy area of 25.31 or 18.42%. In the condition of plantation forests, there was an increase of 35.43%, shrubland of 23.05% and open land of 400.94%. The rate of change in land cover has affected the magnitude of the change in the extent of erosion. This change leads to poor conditions because the area of the very low (<15 tons / ha / year) decreases by 45.94% and low (15-60 tons / ha / year) 2.19%. The addition was actually seen in the very heavy (>480 tons/ha/year) 21.57%, moderate (60-180 tons/ha/year) 28.29% and heavy (180-480 tons/ha/year) 6.45%.

In situ observation and understanding of the arc erosion behavior of electrical contact materials

Abstract Arc erosion studies are carried out on electrical contact materials in the switching current experiment. A test rig is developed to capture the 2-D image and the 3-D profile of eroded silver tin oxide electrical contact material in situ. Image processing algorithms are specially presented to accurately recognize the features of erosion region. The initial small patch of erosion traces gradually evolves into the deep crater with the increment of switching cycle enabling a study of the arc erosion behavior. 2-D image, 3-D profile, and micro surface morphologies of the eroded contacts are analyzed and then related to the extent of erosion. The results show that the evolution process of central erosion region could be divided into the enlargement in breadth of contact surface and the extension in depth of contact profile. The end result of arc erosion is the net loss of contact material, which would lead to the substantial reduction of contact force and potential electrical contact instability.

Spatio-temporal Soil Erosion Estimation in Sangareddy District, Telangana Using Rusle Model

Soil erosion poses a significant environmental challenge worldwide, causing the depletion of fertile topsoil, reduced crop productivity, and heightened sedimentation in water bodies. The extent of erosion depends on factors such as rainfall intensity, land slope, soil type, land use, and management practices. Accurate assessment of soil loss, considering spatial, temporal, and climate change factors, is vital for effective soil and water conservation planning. In this study, a spatial model for estimating soil loss was developed by integrating GIS with the Revised Universal Soil Loss Equation (RUSLE), and validation showed satisfactory results (R2=0.82). The spatial estimation revealed that most of the area experienced soil loss below 5 t ha-1 yr-1, with only a smaller portion showing soil loss exceeding 20 t ha-1 yr-1. To address this, in-situ soil conservation measures are recommended, such as using erosion-resistant crops (e.g., groundnut) in strip cropping, adopting crop rotations, mulching, and planting grasses for bund stabilization. Practices like deep ploughing, summer ploughing, and mixed cropping should also be adopted for sustainable watershed management. Construction of conservation structures like farm ponds and percolation tanks is highly recommended. The study also observed temporal variations in soil loss for Sangareddy district, with the highest soil loss of 134 t ha−1 yr−1 occurring in 2020, and the lowest of 71 t ha−1 yr−1 in 2018. These findings underscore the need for continuous monitoring and adaptive conservation strategies to mitigate soil erosion and ensure sustainable land use practices in the region.

Challenges and progresses in the detailed estimation of sediment export in agricultural watersheds in Navarra (Spain) after two decades of experience

Soil erosion is a very serious environmental problem worldwide, with agriculture considered the main source of sediment in inland waters. In order to determine the extent and importance of soil erosion in the Spanish region of Navarra, in 1995 the Government of Navarra established the Network of Experimental Agricultural Watersheds (NEAWGN), which consists of five small watersheds representative of local conditions. In each watershed, key hydrometeorological variables, including turbidity, were recorded every 10 min, and daily samples were taken to determine suspended sediment concentration. In 2006, the frequency of suspended sediment sampling was increased during hydrologically relevant events. The main objective of this study is to explore the possibility of obtaining long and accurate time series of suspended sediment concentration in the NEAWGN. To this end, simple linear regressions between sediment concentration and turbidity are proposed. In addition, supervised learning models incorporating a larger number of predictive variables are used for the same purpose. A series of indicators are proposed to objectively characterize the intensity and timing of sampling. It was not possible to obtain a satisfactory model for estimating the concentration of suspended sediment. This would be mainly due to the large temporal variability found of the physical and mineralogical characteristics of the sediment, which would be affecting the turbidity value, independently of the sediment concentration, per se. This fact would be particularly important in small river watersheds such as those of this study, and especially if their physical conditions are spatially and temporally radically disturbed by agricultural tillage and by a constant modification of the vegetation cover, as is the case in cereal basins. Our findings suggest that better results could be obtained by including in the analysis variables such as soil texture and exported sediment texture, rainfall erosivity, and the state of vegetation cover and riparian vegetation.

Suffusion prediction model based on physical parameters for gap-graded and well-graded soils

Suffusion is one of the four types of internal erosion and accounts for 46% of erosion phenomena in earth dams. Suffusion is an erosion of fine particles inside the soil structure that move out of the voids between coarse particles caused by permeability flow. Identification of internal erosion is necessary to mitigate the loss of humans and property as underground erosion occurs. However, determining suffusion susceptibility in situ is complex and takes a lot of time. This study proposed a fine-grained erosion prediction model based on physical parameters related to the grading curve and the dry density. Using the principal component analysis (PCA) tool evaluated the influence of these parameters on suffusion. The proposed predictive model of the erosion resistance index (ERI) supports stakeholders in quickly determining the extent of erosion and then taking appropriate measures to maintain the earth dams.

Mapping Abandoned Uranium Mine Features Using Worldview-3 Imagery in Portions of Karnes, Atascosa and Live Oak Counties, Texas

Worldview-3 (WV3) 16-band multispectral data were used to map exposed bedrock and mine waste piles associated with legacy open-pit mining of sandstone-hosted roll-front uranium deposits along the South Texas Coastal Plain. We used the “spectral hourglass” approach to extract spectral endmembers representative of these features from the image. This approach first requires calibrating the imagery to reflectance, then masking for vegetation, followed by spatial and spectral data reduction using a principal component analysis-based procedure that reduces noise and identifies homogeneous targets which are “pure” enough to be considered spectral endmembers. In this case, we used a single WV3 image which covered an ~11.5 km by ~19.5 km area of Karnes, Atascosa and Live Oak Counties, underlain by mined rocks from the Jackson Group and Catahoula Formation. Up to 58 spectral endmembers were identified using a further multi-dimensional class segregation method and were used as inputs for spectral angle mapper (SAM) classification. SAM classification resulted in the identification of at least 117 mine- and mine waste-related features, most of which were previously unknown. Class similarity was further evaluated, and the dominant minerals in each class were identified by comparison to spectral libraries and measured samples of actual Jackson Group uranium host rocks. Redundant classes were eliminated, and SAM was run a second time using a reduced set of 23 endmembers, which were found to map these same features as effectively as using the full 58 set of endmembers, but with significantly reduced noise and spectral outliers. Our classification results were validated by evaluating detailed scale mapping of three known mine sites (Esse-Spoonamore, Wright-McCrady and Garbysch-Thane) with published ground truth information about the vegetation cover, extent of erosion and exposure of waste pile materials and/or geologic information about host lithology and mineralization. Despite successful demonstration of the utility of WV3 data for inventorying mine features, additional landscape features such as bare agricultural fields and oil and gas drill pads were also identified. The elimination of such features will require combining the spectral classification maps presented in this study with high-quality topographic data. Also, the spectral endmembers identified during the course of this study could be useful for larger-scale mapping efforts using additional well-calibrated WV3 images beyond the coverage of our initial study area.

Rapid magnetic susceptibility measurement as a tracer to assess the erosion–deposition process using tillage homogenization and simple proportional models: A case study in northern of Morocco

Soil erosion is a significant threat in the Rif region in northern Morocco. Hence, accurate cartography of the phenomenon, magnitude, and extent of erosion in the area needs a simple, rapid, and economical method such as magnetic susceptibility (MS). The current study aims to: (i) determine the factors influencing the variation of soil MS, (ii) exploit MS to estimate soil loss using two approaches in different homogenous units characterized by the same climatic conditions with different edaphic characteristics (land use, slope, and lithology), and (iii) highlight the potential for using MS as a cheap and rapid tracer of a long term erosion and deposition processes. Mass-specific magnetic susceptibility at low (χlf) and high (χhf) frequencies were measured for 182 soil samples collected in the study area. A tillage homogenization (T-H) model and a simple proportional model (SPM) were applied on an undisturbed soil profile to predict the eroded soil depths for given cores. The results confirm that χlf is influenced by land use, slope, and soil type. Pedogenesis is the main factor affecting soil MS enhancement, indicated by homogenous magnetic mineralogy with a dominance of super-paramagnetic (SP) and stable single domain (SSD) magnetic grains. The study results show that higher soil losses have occurred in almost all the soil samples when applying the T-H model compared to application of the SPM. The SPM underestimates erosion due to its ignorance of the MS of the plow layers after erosion. The current study implies the high efficacy of magnetic susceptibility as the quick, easily measurable, simple, and cost-effective approach that can be used as an alternative technique for evaluating soil redistribution.

First evidence of widespread, severe soil erosion underneath centre-pivot irrigation systems

Centre-pivot systems are widely used for irrigation in agriculture. However, excessive water application rates under low pressure centre-pivot systems can lead to soil erosion, which degrades soil structure and increases crop vulnerability to droughts. Although efforts have been deployed to measure soil erosion underneath individual centre pivots, a large-scale systematic assessment of extent and severity of soil erosion in centre-pivot irrigated fields is currently lacking. Here we used Google Earth™ satellite images to provide first evidence of widespread, severe soil erosion in centre-pivot irrigated agricultural land. We focused on the municipality of Cristalina (6154 km2), in the Brazilian Central Highlands, where centre pivots irrigate approximately 60,000 ha of cropland. The study area is in the Cerrado biome, which is one of the most important grain-producing regions in the world and Brazil's main centre-pivot irrigation area. By mapping erosion features under centre pivots, we found that 29 % of centre-pivot fields displayed signs of rill erosion, with individual rills up to a length of 1200 m. Most erosion features were identified during the dry season of the Brazilian Cerrado, which coincided with the period of greater satellite-image availability. Moreover, we found that compacted centre-pivot-wheel tracks often triggered rill incision and that eroding centre-pivot fields displayed higher slope gradients and were better connected to surface waters than the non-eroding fields. Ultimately, the frequent identification of severe erosion features in the centre-pivot fields during the dry season indicates that irrigation causes and/or aggravates soil erosion in Cristalina and likely in other parts of the Brazilian Cerrado. This first systematic evidence of widespread soil erosion underneath centre-pivot systems highlights that irrigation erosion is an important but neglected driver of land degradation, and that urgent action is required to protect affected soils for future generations.

The impact of coastal erosion on the archaeology of the Cyrenaican coast of Eastern Libya.

Coastal erosion in Cyrenaica (Eastern Libya) represents a major problem for archaeology and heritage management. The area is rich in archaeological sites, often understudied or not fully documented, but also has extensive stretches of vulnerable eroding coastline. This study demonstrates the extent and impact of erosion via shoreline change assessment at two spatial scales. Firstly, wide area assessment using shorelines extracted from a time-series of medium-resolution Landsat imagery. Secondly, site-specific assessment using recent and historic Very High Resolution (VHR) satellite imagery. In both cases, extracted shorelines at different timesteps were compared using the Digital Shoreline Analysis System (DSAS) tool to quantify rates and magnitudes of shoreline movement. The results show extensive zones of erosion at and around the key ancient harbour sites of Apollonia, Ptolemais and Tocra. They also suggest increased rates of coastal retreat in recent years, which is likely linked to anthropogenic actions such as sand mining and urbanization. Forecasts based on present-day shoreline change rates, coupled with ground-level documentation of the vulnerable shorelines is used to identify archaeological features and structures which will likely be progressively damaged or destroyed over the next 20 years. The ability to actively protect archaeological sites is unclear, but there is a clear need for mitigation in the form of enhanced awareness of environmental problems (e.g. caused by sand mining) and more intensive survey/documentation of sites and areas which will be lost in the coming years.

Integrating Erosion Potential Model (EPM) and PAP/RAC Guidelines for Water Erosion Mapping and Detection of Vulnerable Areas in the Toudgha River Watershed of the Central High Atlas, Morocco

This study aimed to evaluate the extent and severity of water erosion in the Toudgha river catchment in the Central High Atlas of Morocco using two different erosion models, the Erosion Potential Model (EPM) and the Priority Actions Programme/Regional Activity Centre (PAP/RAC) model. From the modeling results, the catchment was affected by varying degrees of erosion, ranging from “very slight” to “excessive”, with different locations identified under each model. The very high erosion areas were located in the extreme northwest of the catchment area for both of the applied models, covering 9.65% (according to PAP/RAC) and 8.56% (EPM) of the total area primarily driven by factors such as intense rainfall events, limited vegetation cover, high soil erodibility due to low organic matter content and coarser soil texture, and human activities such as overgrazing and land use changes, which exacerbate the effects of these natural factors on water erosion in these semi-arid areas. The study’s findings suggest that erosion is a significant concern in these environmental areas and provide valuable information for designing effective erosion control measures and guiding soil and environmental management practices. Both models effectively simulated the erosion phenomenon and provided useful tools for soil and environmental management. The EPM model can be used to design effective erosion control measures, while the PAP/RAC model can be used to develop a comprehensive strategy for the sustainable management of the catchment area. These results have implications for the implementation of effective erosion control measures in mountainous watersheds and highlight the need for further research in this area.

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

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

Split-bolus, single-phase contrast enhanced CT: a one-stop shop for invasive fungal sinusitis.

Contrast-enhanced magnetic resonance imaging is considered the imaging modality of choice for invasive fungal sinusitis (IFS); however, it is not feasible to perform emergency CEMRI especially in the setting of COVID-19. The CECT protocol for evaluation of suspected IFS can be modified by using split-bolus, single-phase CT as it provides an optimal soft tissue demonstration of sinonasal disease; extrasinus spread to orbit, and intracranial involvement along with simultaneous opacification of the internal carotid artery and cavernous sinus. The extent of bone erosion can also be well delineated on the multiplanar reconstructions (MPRs) in the bone window. Further a structured reporting format can help provide optimal surgical guidance in cases of IFS.

The Role of Serum Galactomannan Assay as a Potential Surrogate Biomarker for Fungal Microinvasion in Allergic Fungal Rhinosinusitis.

We conducted this study to determine if serum galactomannan (GM) can be used as a marker to implicate the invasiveness of allergic fungal rhinosinusitis (AFRS), and correlate this value with the aggressiveness of disease documented via computed tomography (CT). All paranasal CT scans done for AFRS patients prospectively over a five-year period (2015-2019) were included. An indigenous 20-point score was used to document the extent of bone erosion seen on CT, wherein a higher score meant a greater extent of bone erosion. It was then correlated with serum GM scores. The median CT scores of galactomannan-positive (GM+) patients were compared with the median CT scores of galactomannan-negative (GM-) patients 3 using Mann-Whitney U test. The patients were divided into five groups based on the extent of disease-No bone erosion, erosion of only sinus wall/orbit, 3 erosion of orbit and skull base, erosion of only skull base and lateral extension of disease into infratemporal fossa (ITF). Subgroup analysis was conducted over mean GM values in these groups using ANOVA test. p-value < 0.05 was considered significant. Statistical analysis was performed using SPSS version 25.0. A total of 92 patients were included (56 males, 36 females). No statistically significant difference was found (p-value = 0.42) between the CT scores of galactomannan-positive (GM+) group and galactomannan-negative (GM-) group. The mean GM scores amongst the five sub-groups did not show a statistically significant difference. Serum galactomannan values correlate poorly with aggressiveness of disease quantified on non-contrast CT of paranasal sinuses.

Clinical Profile of Squamosal Chronic Otitis Media among Paediatric and Adult Patients in Rural Population of Central India: A Cross-sectional Study

Introduction: Chronic Otitis Media (COM) is one of the major preventable causes of hearing impairment, especially in children. Hearing loss in children affects speech, language, communication, auditory processing, psychosocial and cognitive development, and academic progress. Since studies addressing and comparing COM in the paediatric and adult population are few and far between, present study attempted to fill this research hiatus. Aim: To analyse and compare the clinical profile of squamosal COM in paediatric and adult populations. Materials and Methods: The present cross-sectional study was carried out in the Department of Otorhinolaryngology, Acharya Vinod Bhave Hospital, Sawangi, Wardha, Maharashtra, India, from December 2020 to December 2022. All the selected patients with squamosal COM (active or inactive) in the paediatric age group (0-15 years) and adult age group (16-60 years) was considered in this study. The study included 26 patients and was evaluated based on intraoperative and radiological findings such as grades of retraction pocket, extent of ossicular erosion, extent, and spread of granulation and cholesteatoma, and pneumatisation pattern among both age groups were carefully analysed. Chi-square test (χ2 ) of independence was used to compare data between the two groups. A p-value ≤0.05 was considered statistically significant. Results: Erosion of scutum was predominantly noted in 6 (42.9%) paediatric patients. In both age groups, attic perforation were more common than marginal perforation, which was found to be statistically significant (p-value=0.045). Grade-2 Posterosuperior Retraction Pocket (PSRP) in paediatric (2, 14.2%) and Grade-4 PSRP in adults (4, 33.3%) were commonest whereas none of the paediatric patients showed Grade-4 PSRP. This difference in PSRP grade in both age groups was found statistically significant (p-value=0.038). Short process of incus was more frequently involved in 3 (25.0%) paediatric and long process of incus in 6 (60%) adult (p-value=0.040). There was frequent involvement of protympanum in 7 (50%) paediatric patients (p-value=0.035). Diploic pattern of pneumatisation was least common in both age groups. Conclusion: Greater grades of PSRP were found among adult patients. This might be contributed to the longer duration of exposure to disease pathogenesis in adults. One of the vital features in the ossicular involvement is the total absence of incus and malleus more frequently in paediatric patients indicating its extensiveness

Analysis of internal erosion in granular soil during deep excavation with a Water-Inrush incident in a covered karst area

Internal erosion of granular soil causes instability in the soil skeleton due to fine particles being washed out. Using the case of water inrush occurring in excavation engineering, the characteristics of the grain size distribution of the soil samples are analysed. Granular soil with a potential of suffusion is evaluated in detail. A practicable method including both prediction for the process of gradually updating the grain size distribution and calculation of the critical hydraulic gradients for the various particle sizes is proposed, which is based on the graded erosion principle. Consequently, a solution for evaluation of the flux rate and the erosion extent by hydraulic parameters of granular soils is concluded. A numerical model for the water inrush simulation is employed to validate the method. The results show that the solution is effective in both prediction of the water flux rate and evaluation of the internal erosion extent.

Imaging of Insect Hole in Living Tree Trunk Based on Joint Driven Algorithm of Electromagnetic Inverse Scattering.

Trunk pests have always been one of the most important species of tree pests. Trees eroded by trunk pests will be blocked in the transport of nutrients and water and will wither and die or be broken by strong winds. Most pests are social and distributed in the form of communities inside trees. However, it is difficult to know from the outside if a tree is infected inside. A new method for the non-invasive detecting of tree interiors is proposed to identify trees eroded by trunk pests. The method is based on electromagnetic inverse scattering. The scattered field data are obtained by an electromagnetic wave receiver. A Joint-Driven algorithm is proposed to realize the electromagnetic scattered data imaging to determine the extent and location of pest erosion of the trunk. This imaging method can effectively solve the problem of unclear imaging in the xylem of living trees due to the small area of the pest community. The Joint-Driven algorithm proposed by our group can achieve accurate imaging with a ratio of pest community radius to live tree radius equal to 1:60 under the condition of noise doping. The Joint-Driven algorithm proposed in this paper reduces the time cost and computational complexity of tree internal defect detection and improves the clarity and accuracy of tree internal defect inversion images.