Erosion Area Research Articles

Assessing the Impact of Coastal Erosion on Land use and Landcover, A Time Series Analysis using DSAS and GIS in Cuddalore Shore, Tamil Nadu, India

Abstract One of the most fragile places on earth is the coastal zone. There are several different ecosystems in this area. In this area, erosion and accretion are typical natural occurrences. These changes could also threaten the coastal ecology. Uneven coastal changes can result from natural processes such rainfall, cyclones, floods, tectonic shifts and longshore drift. Similar to this, anthropogenic influences like mining, unscientific land use, urbanisation, etc., contribute to coastal processes and bring much more significant alterations in the coastal region. Therefore, identifying such a location is crucial. Advanced approaches for studying shoreline change have been made possible by geospatial technology. The enormous effort to obtain an accurate result over a greater area has become easier as a result. In order to examine the changes in the Cuddalore shoreline during the years 2002, 2007, 2013, 2017, and 2022, Landsat satellite imageries with 30 m spatial resolution were used. The Digital Shoreline Analysis System (DSAS) tool for analysing shoreline change has been integrated to Geographic Information System (GIS) software. DSAS was used to construct the baseline transects for the shoreline change measurement. Using the MATLAB feature runtime function for ArcGIS, the rate of shoreline change was computed. Based on the DSAS output, the area of high erosion, low erosion, stable, and low accretion, high accretion zones were assessed on the coastline. The results reveal that 15.38% of the shoreline, around 6.8 km is under high erosion. 12.2% of the shoreline, which is around 5.4 km, is under low erosion. 32% of the shoreline, around 14.5 km, is a stable region. 26.9% of shorelines, around 11.9 km, is low accretion, and 12.6% of shorelines, around 5.6 km, is high accretion. The coastal villages, namely, Gundupallavadi, Cuddalore, Thandavarayancholanga pettai, Ariyakoshti and parangipettai have a high erosion with a maximum rate of change between -3 to -14 m/y. The coastal villages Patchayankuppam, Cuddalore, Tiruchchepuram, Kayalpattu, Kothattai, Ariyakoshti, Parangipettai have high accretion with a maximum rate of change between 3 to 10 m/y.

РАЗРУШЕНИЕ ДЕЛЬТЫ РЕКИ ТУМАННОЙ В ГОЛОЦЕНОВОЕ ВРЕМЯ И ФОРМИРОВАНИЕ ПРИПОВЕРХНОСТНЫХ СКОПЛЕНИЙ ГАЗА НА ШЕЛЬФЕ ЗАПАДНОЙ ЧАСТИ ЗАЛИВА ПЕТРА ВЕЛИКОГО (ЯПОНСКОЕ МОРЕ)

The results of bathymetric and seismoacoustic studies of the shelf in the western part of Peter the Great Bay are presented. Five flooded coastlines formed in the Late Pleistocene-Holocene were identified on the shelf. It was found that a significant part of the shelf is occupied by a zone of irregular sedimentation, which is underlain by an erosion surface buried under sediments of ebb-tidal deltas in areas of active sedimentation and exposed on the seabed within the area of active modern erosion. The processes of abrasion and formation of an irregular sedimentation zone on the shelf intensified about 11500–11700 years ago. Acoustic anomalies associated with the presence of gas in sediments and gas flares in the water column were found on the shelf of the Bay. Anomalies were classified by types, and a map of their areal distribution was compiled. It is concluded that the trigger mechanism that ensures the migration of gas into sediments and water column is associated with a group of factors: postglacial sea level change, abrasion processes, meteorological and hydrological regimes.

Advancing Soil Erosion Assessment: Application of Remote Sensing and Geospatial Techniques in Bulango Ulu Reservoir Basin

Soil erosion is an important concern due to the steepness of the terrain and the significant elevation differential between the upstream and downstream regions of the basin. Revised Universal Soil Loss Equation (RUSLE) was integrated with Remote Sensing (RS) and Geographic Information System (GIS) in the current work establish the annual soil erosion map in the Bulango Ulu Reservoir basin. The RUSLE model incorporated soil erosion zonation features such as rainfall erosivity, soil erodibility, topographic, vegetation cover, and conservation support practices. The results show that 0 and 110.31 t year−1 are the minimum and maximum soil erosion, with the average rate of soil erosion is 17.30 t year−1 in the present study area. Soil erosion risk regions were divided into five categories: very slight, slight, moderate, severe and extremely severe soil erosion areal extent and area percentages is 229.17 km2 (94.48%), 7.83 km2 (3.23%), 4.25 km2 (1.75%), 1.20 km2 (0.50%), and 0.12 km2 (0.05%), respectively. The Area Under Curve was indicated that RUSLE model had good performance (75.1%). This study demonstrates the utility of GIS and remote sensing for predicting soil erosion, allowing important information to be extracted for implementing soil conservation programs in the Bulango Ulu reservoir basin.

Варианты патогенетического лечения аспирининдуцированных гастроэнтеропатий у лиц с хронической ишемической болезнью сердца

Aim: Evaluation of Rebamipide treatment efficiency for aspirin-induced gastroduodenopathy in the patients with stable coronary heart disease (CHD). Design: Randomised controlled study. Materials and methods: In the course of the conducted research 340 CHD patients receiving long-term acetylsalicylic acid therapy in cardioprotective doses were studied. All the patients received complete clinical laboratory examination. For CHD verification there was applied selective method of coronary angiography. Gastroduodenopathy was verified by esophagogastroduodenoscopy. In both cases frequency and structure of the aforesaid events were assessed. For aspirin-induced gastroduodenopathy treatment there were applied either endogenic prostaglandin stimulant Rebamipide in combination with proton pump inhibitor (PPI) Pantoprazole (study group, n = 26) or Pantoprazole only (control group, n = 25). Prior to initiating therapy and on completion all the patients were taken blood samples for evaluation of prostaglandin E2 (PGE2) and proinflammatory cytokines (interleukine-1β Il-1β and interleukine-6 Il-6, TNF-α) levels in blood serum for verification of pathogenetic mechanisms in erosive or ulcer-bearing areas developing in gastrointestinal mucosa in association with long-term aspirin therapy. Соntrol group consisted of 26 CHD patients with no evidence of gastroduodenopathy. Statistical processing of the received data was conducted with the software program “Statistics 10.0”. Results. Aspirin-induced gastroduodenopathy was identified in 51 out of 340 (15,0%) cases. According to esophagogastroduodenoscopy data, erosions of the body and antrum of stomach were prevailing (43,1%) over all the erosive damages. CHD patients before the gastroduodenopathy treatment had significantly lower PGE2 levels in comparison with control group (p < 0,01), while proinflammatory cytokines indices were higher (p < 0,001). On the treatment completion 19 patients in the control group did not show endoscopic evidence of gastroduodenopathy, the laboratory findings tended to normalization. Gastric mucosa condition in the study group stabilized in all the cases, which was confirmed by statistically significant PGE2 level positive alterations (p < 0,001) and also cytokine profile alterations (TNF-α: p < 0,001; Il-1β and Il-6: p < 0,01). Conclusion. The presented study demonstrates clinical features of aspirin-induced gastroduodenopathy development in the CHD patients and proposes possible ways of correction. Key words: aspirin-induced gastroduodenopathy, acetylsalicylic acid, prostaglandin E2, proinflammatory cytokines, rebamipide.

Construction of benthic integrated biotic index and health assessment in different soil erosion areas of Wuding River Basin

Construction of benthic integrated biotic index and health assessment in different soil erosion areas of Wuding River Basin

Depth‐dependent responses of the soil bacterial community under vegetation restoration in soil erosion areas of southern China

AbstractSoil bacterial communities play a crucial role in the evaluation of soil ecosystem stability. Vegetation restoration is a key determinant of soil bacterial communities in areas affected by soil erosion. However, it remains unclear how the structure and diversity of soil bacterial communities vary with soil depth. In this study, we collected soil samples from 0 to 10 cm, 10 to 20 cm, 20 to 30 cm, and 30 to 40 cm depths in vegetation restoration sites located in typical soil erosion areas in China. We compared and analyzed the differences in bacterial community characteristics among different soil depths, using untreated areas as controls. Compared to the untreated areas, the abundance of soil bacteria in the 0–10 cm, 10–20 cm, and 20–30 cm depths of the vegetation restoration sites increased by 1.63, 1.04, and 1.29 times, respectively. Furthermore, vegetation restoration enhanced soil bacterial diversity at the 0–10 cm, 10–20 cm, and 20–30 cm depths. Soil organic carbon (OC) was the main explanatory factor (53.50%, p = 0.000) for the decrease in soil bacterial diversity with soil depth. Additionally, after vegetation restoration in soil erosion areas, the dominant bacterial community composition shifted from Chloroflexi to Actinobacteria at the 0–10 cm, 10–20 cm, and 20–30 cm depths and to Proteobacteria at the 30–40 cm depth. The differences in soil bacterial communities among different soil depths were primarily driven by soil total nitrogen (TN) content, which explained up to 34.5% of the variation. In conclusion, in the subsequent management of vegetation restoration sites, increasing OC and TN content can enhance soil bacterial diversity, improve bacterial community composition, and ultimately enhance the stability of soil ecosystems.

Evaluation of the Effectiveness of Amlexanox in the Treatment of Erosive Oral Lichen Planus: A Clinical Experience from a Tertiary Care Center.

This comparative study evaluated the effectiveness and safety profile of topical amlexanox and triamcinolone for the management of erosive oral lichen planus (EOLP). This prospective, observational study included 21 patients diagnosed clinically and histopathologically with EOLP and categorized into two groups. Subjects in the two groups were prescribed topical amlexanox and triamcinolone, respectively, for 4 weeks. The area of the erosive lesion and burning sensation was measured at baseline, at the end of the first, 2second, and fourth week. These outcome measures were documented and statistically analyzed. The statistical analyses were performed using the IBM SPSS Statistics version 22. Analysis for age distribution was done by independent sample t test. Analysis of sex distribution was done by chi-square test. Variations within a single group for both the outcome parameters were calculated by Wilcoxon signed rank test. (P < 0.05 statistically significant). A total of 30 erosive sites were evaluated in 21 patients over a 4-week duration. The most common site was the buccal mucosa in both groups (23 of 30; 76.67% of total lesions assessed), followed by the tongue (5 of 30; 16.67% of total lesions assessed), the palate (1 of 30; 3.33% of total sites assessed), and the maxillary attached gingiva (1 of 30; 3.33% of total sites assessed). Group 1 (amlexanox) was comprised of 11 subjects, whereas Group 2 (triamcinolone) was comprised of 10 subjects. Pre and posttreatment comparison revealed no statistically significant difference (P = 0.756; 0.512, respectively), for the area of the erosion and burning sensation. Intragroup analysis showed that in Groups 1 and 2, there was a statistically significant reduction in the measures posttreatment (P < 0.05). Amlexanox provides an earlier onset of pain relief in the treatment of EOLP, whereas providing a comparable reduction in the erosive area compared with triamcinolone. Topical amlexanox appears to be as effective as triamcinolone and is a promising alternative in the management of the erosive lichen planus with minimal adverse effects.

Shoreline Change Assessment in the Orashi River, Rivers State, Nigeria, using the Digital Shoreline Analysis System (DSAS)

Shoreline change profoundly impacts coastal geology and coastal communities. This study, spanning three decades from 1992 to 2022, employed the Digital Shoreline Analysis System (DSAS) to assess the Orashi River shoreline dynamics in Nigeria. Using Landsat imagery data from the United States Geological Survey (USGS) and ArcGIS 10.6, DSAS 5.0 software was utilized for analysis. Various statistical methods, including Linear Regression Rate (LRR), Weighted Linear Regression (WLR), End Point Rate (EPR), Net Shoreline Movement (NSM), and Shoreline Change Envelope (SCE), quantified shoreline changes. The findings consistently reveal significant shoreline regression. LRR, -1.78 to -1.07, highlights continuous landward movement, signifying erosion’s persistent impact. WLR rates reaffirm this trend, closely mirroring the range of -1.78 to -1.07. EPR, -2.79 to -1.29, further underline the erosional trend, emphasizing substantial inland shifts. NSM, ranging from -48.66 to -20.30, signifies substantial shoreline retreat, showcasing erosion’s profound effect. The NSM, varying from 0.69 to -11.50, illustrates dynamic shoreline movement with varying degrees of erosion. The outcomes identify prevalent erosion, particularly in Very High Erosion (VHE) areas, while High Accretion (HA) and Very High Accretion (VHA) zones experience shoreline gain. These classifications inform coastal management strategies, urging protective measures for VHE areas and development opportunities in HA and VHA zones. The variability in shoreline change underscores coastal dynamics’ complexity. This study contributes to understanding the Orashi River’s shoreline processes, guiding sustainable coastal management and environmental conservation efforts. Continued monitoring and research are crucial for adapting to the evolving coastal landscape’s impact on the environment and local communities.

An improved method combined modified drag model and modified erosion model based on LES for solid-liquid multiphase flow and erosion with application in a 90° elbow

In various industrial processes, solid-liquid multiphase flows involving continuous carrier and discrete particle phases have erosion challenges. In this work, a modified drag model that considers the influence of turbulence intensity and a modified erosion model that considers the effect of low-angle impact are developed. An improved method combined modified drag model and modified erosion model based on LES is proposed for numerical simulation of solid-liquid multiphase flow and erosion. The commercial software ICEM for grid generation and ANSYS FLUENT for LES are used in the present work. In validation test of velocity distribution of solid-liquid multiphase flow in a vertical pipe, the mean relative error of the liquid phase pulsation velocity is 10.01 % for modified drag model, whereas the mean relative error is 16.11 % for original drag model. In validation test of the maximum erosion depth from a submerged impact test at a tilt angle of 45°, the relative error is 0.23 % for modified erosion model, while the relative error is 13.39 % for original erosion model. Then, the improved method is employed to compute the characteristics of solid-liquid flow and erosion in a 90° elbow. Particles have a significant influence on liquid flow in the shear layer area where the inner arch separation zone interacts with the main flow, and this influence is most pronounced at the position of r* = 0.3 at yd = 0.4D. At this position, particles result in 15.27 % reduction in liquid velocity and 8.75 % increase in turbulence intensity. The mean relative error of the elbow erosion rate by using the improved method is 16.95 %, whereas it is 31.34 % of the reference work. The erosion is affected by impact velocity, angle, and particle number, and the most significant parameter is the particle number in the severe erosion area.

Efficacy of Aloe Vera, Amlexanox (5%), and Triamcinolone Acetonide (0.1%) in the Management of Oral Lichen Planus.

This research assessed the efficiencies of aloe vera, 0.1% triamcinolone acetonide, and 5% amlexanox in the management of OLP. A total of 120 participants diagnosed with oral lichen planus (OLP) were equally divided into three groups and treated with: aloe vera, (Group A), 0.1% triamcinolone acetonide (Group B), and 5% amlexanox (Group C) topical medicaments. The patients were evaluated for pain, using the visual analogue scale (VAS). They were also evaluated for ulcerative lesion type and erosive area on days 1, 7, and 15 of the study. There was a statistically considerable decrease in the VAS pain scale score, reduction in the erosive area on buccal mucosa, and healing of ulcer from day 1st to 15th day with all three tested drugs. All drugs used in this study; aloe vera, triamcinolone acetonide, and amlexanox were effective in treating OLP patients.

Efficacy of Clobetasol Propionate (0.05%), Amlexanox (5%), and Triamcinolone Acetonide (0.1%) in the Treatment of Oral Lichen Planus.

This study aimed to compare the efficiencies of 0.05% clobetasol propionate, 0.1% triamcinolone acetonide, and 5% amlexanox in the management of oral lichen planus (OLP). A total of 120 patients diagnosed with oral lichen planus were equally divided into three groups and treated with 0.05% clobetasol propionate (group A), 0.1% triamcinolone acetonide (group B), and 5% amlexanox (group C) topical medicaments. The patients were evaluated for pain using the visual analog scale (VAS) and erosive lesion. There was a statistically significant decrease in the VAS pain scale score from day 1 to day 15 in all of the tested groups. There was also a reduction in the erosive area on the right and left buccal mucosa on the 15th day with all three tested drugs. Triamcinolone acetonide (0.1%) was effective in reducing the erosive lesions on buccal mucosa when compared with 0.05% clobetasol propionate and 5% amlexanox. Clobetasol propionate, triamcinolone acetonide, and amlexanox were effective in treating OLP patients.

Effects of microtopography shaping on characteristics of eroded sediment particles of a dump slope in an opencast coal mine in China

AbstractThe properties of sediment particles are crucial research areas for understanding soil erosion on dump slopes. In this study, the slope of the southern dump of the ATB opencast coal mine in the Pingshuo mining area in Shanxi Province, China, was selected to conduct microtopographical shaping and artificial rainfall simulation experiments. Three different gradients of rainfall intensity, 20, 50, and 80 mm·h−1, were set. The main component of rainwater was water (chemistry H2O) by a rainfall duration of 30 min. A Microtrac S3500 laser particle size analyzer was used to measure the collected erosion sediment particles. This study conducted level benches and fish‐scale pits microtopography shaping on the slope of the waste dump. The dimensions of the level bench design were 1, 2, and 1 m for the step width, for the step length, and between each level bench, respectively. The fish‐scale pits were 60 cm (length), 40 cm (width), and 30 cm (depth). The horizontal and row spacing of each fish‐scale pit was 1 m, and an unshaped terrain was used as the control group. Through dynamic monitoring and statistical analysis of the data, the impacts of rainfall intensity and microtopography shaping mode on the features of the eroded sediment particles were analyzed. Fine silt particles (53%) were lost as a result of the surface erosion of the slope. The mean starting periods of sediment particle loss decreased with the increase in rainfall intensity (589 s &gt; 402 s &gt; 305 s). Additionally, the clay and silt particle enrichment ratios decreased (ER &gt;1), whereas the sand particle enrichment ratios increased (ER &lt;1). The level benches had a stronger interception effect on fine sediment, whereas the fish‐scale pits had a weaker interception effect on sediment particles under heavy rain. The distribution properties of erosion sediment particles on a slope can be assessed using fractal dimension as an index. This study is significant for understanding the erosion mechanism of eroded sediment particles on dump slopes and provides a scientific foundation for soil erosion control on opencast coal mine dump slopes in the Loess Plateau. These results highlight the potential for the level bench to effectively delay the occurrence of runoff and greatly enhance the interception of sediment particles.

Numerical investigation on influences of injection angle of bottom blowing bubbles on multiphase flow characteristics and wall erosion of converter

In this work, a novel bottom blowing approach based on inclined injection bubbles to enhance the multiphase flow mixing is proposed. An Eulerian-Eulerian model, validated via published experimental data, is established to numerically reproduce the stirring process of a bottom blowing converter. The effects of injection angle on the multiphase flow characteristics and wall erosion are then systematically investigated. Firstly, the influence of bottom blowing flow rate (10 m/s, 14 m/s, 20 m/s) on the mixing efficiency is discussed. Then, the effects of injection angle (0°, 5°, 10°, 15°, 20°) on the flow characteristics, mixing efficiency and wall erosion are studied in detail based on the bottom blowing flow rate of 14 m/s. The results show that increasing the bottom blowing flow rate is beneficial to shorten the mixing time. With the increase of the injection angle, the mixing time first decreases and then increases. As a result, the optimal angle for the most efficient mixing is determined as 5° when the flow rate is 14 m/s. When the injection angle is 5°, the air velocity on the axis and the negative tangent line is maximum. But the velocity is minimal on the positive tangent line. The injected air forms bubble plume that promotes the circulation of water. The most serious erosion area of the converter wall is located at the junction of molten steel surface and converter wall, followed by vicinity of the tuyere. However, with the increase of the injection angle, the average wall shear stress fluctuates only slightly. The obtained results are helpful to better understand the mechanism of bubble flow field in gas-liquid two-phase and also to improve the smelting efficiency in iron and steel metallurgy.

Soil organic carbon induces a decrease in erodibility of black soil with loess parent materials in northeast China

Abstract Although black soil in northeast China undergoes severe erosion, the contribution of parent materials, mainly Quaternary loess and non-loess sediments, to soil erodibility remains unclear. Considering the inheritance of ferromagnetic materials by parent materials, changes in magnetic parameters can successfully determine soil erodibility on a regional scale with a close climatic background. Here, we analysed the magnetic indicators of 142 samples from the black soil horizon formed on loess and non-loess sediments, covering areas of severe and slight erosion in the region to determine the effects of parent materials on the erodibility of black soil in northeast China. Both low-frequency magnetic susceptibility and frequency magnetic susceptibility (χfd) were proportional to the decrease in erosion rate due to erosion-induced leaching of ferromagnetic materials, and the change in χfd was narrow for black soil with loess parent materials, corresponding to relatively low soil erodibility. Compared with loess, the addition of soil organic matter could stabilise soils against erosion, thereby inducing a decrease in the erodibility of black soil formed on loess. Additionally, sustainable soil management policies to protect black soil from further erosion are necessary and urgent under the pressure of maintaining high grain yields and preventing erosion in northeast China.

Analysis of Farmers Benefits from Land Use in Erosion Areas of Ulza Watershed

Analysis of Farmers Benefits from Land Use in Erosion Areas of Ulza Watershed

Optimization of fracturing stages/clusters in horizontal well based on unsupervised clustering of bottomhole mechanical specific energy on the bit

Multi-cluster perforation and multi-staged fracturing of horizontal well is one of the main technologies in volumetric fracturing stimulation of unconventional oil and gas reservoirs, but unconventional reservoirs in China are generally of strong heterogeneity, which causes different fracture initiation pressures in different positions of lateral, making it difficult to ensure the balanced fracture initiation and propagation between clusters in multi-cluster perforating. It is in urgent need to precisely evaluate the difference in rock strength in lateral and determine the well section with similar rock strength to deploy fractures, so as to reach the goal of balanced stimulation. Based on the drilling and logging data, this paper establishes an unsupervised clustering model of mechanical specific energy of bit at the bottomhole the lateral. Then, the influence of drill string friction, composite drilling and jet-assisted rock breaking on the mechanical specific energy is analyzed, and the distribution and clustering categories of bottomhole mechanical specific energy with decimeter spatial resolution are obtained. Finally, a fracture deployment optimization method for horizontal well volumetric fracturing aiming balanced stimulation is developed by comprehensively considering inter-fracture interference, casing collar position, plug position, and clustering result of bottomhole mechanical specific energy. The following results are obtained. First, compared with brittleness index, Poisson's ratio and stress difference, perforation erosion area is in a stronger correlation with the mechanical specific energy, and the mechanical specific energy can effectively characterize the difference in the amount of proppant injected into the perforation clusters in the lateral, so it can be served as one of the important indicators for the selection of fracture deployment position. Second, the drilling and logging data cleaning and smoothing and the clustering number selection by the elbow method are the key steps to obtain the clustering results of bottomhole mechanical specific energy, which can tell the difference in the mechanical specific energy with decimeter-level resolution. Third, the interval with mechanical specific energy within 10% of the average value in the section is selected for deploying perforation clusters, and the compiled computer algorithm can automatically determine the optimal position of fracturing section and cluster, so as to realize the differential design of stage spacing and cluster spacing. In conclusion, the research results can further improve the fractures deployment efficiency and balanced stimulation of volumetric fracturing in unconventional oil and gas reservoirs, and this technology is expected to provide ideas and new methods for the fracture deployment optimization of horizontal well volumetric fracturing in unconventional oil and gas reservoirs.

Using river restoration model to control riverbank erosion in the Old Brahmaputra river of Bengal Basin, Bangladesh

River meandering causes riverbank erosion, which triggers socioeconomic and environmental issues in the riparian region and raises river sedimentation, thus, needing river restoration. This research depicts a channel restoration model to control river bank erosion and susceptible resource management along the Old Brahmaputra River course based on channel characteristics from 1980 to 2021. The secondary data of Landsat satellite time series and SRTM images were collected from the USGS website, while we used Google Earth images to verify the morphological features. Satellite images were on-screen visualized by ArcMap (10.3) to extract the river channels and measure the erosion and accretion areas. Results showed that the Old Brahmaputra River channel shifted its position due to erosion and accretion. Over the last forty-one years, ∼ 52 km2 area was eroded while ∼ 49 km2 area was accreted, and the average shifting of the river channel was 1.3 km2 per year. Accordingly, the river channel has become more sinuous decade by decade and threatens nearby settlements. Hence, this study proposed a river channel based on previous river channels, where the base channel is from the 2000s, which was more stable and flowed through the middle of the floodplain. Parts of the 1980, 2000, and 2021 river channels were also selected, which are relatively far from the susceptible settlements, to draw the proposed restoring channel. This model is likely to aid in developing government strategies for protecting riverbank erosion and river restoration in the forthcoming period. Finally, this study recommends that this newly proposed channel will be conducive to reducing riverbank erosion and the extreme threat to the settlements and their livelihoods.

Scouring erosion resistance of nano-marine concrete under the coupled effect of chloride attack and dry - wet cycles

In order to reveal the improving mechanism associated with different types of nanoparticles under the three-factor coupled effects (scour, dry-wet cycles, and Cl- attack), a laboratory investigation was undertaken to evaluate and compare the influence of nano-SiO2 and nano-Fe3O4 with different content on scouring erosion resistance properties of marine concrete. The micro-structure of the interface transition zone (ITZ) in marine-concrete, as well as the features of hydration products, were characterized using advanced techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), differential thermal gravimetric (DTG-DSC) analysis, and mercury intrusion porosimetry (MIP). The test results showed that compressive and flexural strength, as well as scouring erosion resistance of marine-concrete were enhanced with the increasing content of nano-SiO2 and nano-Fe3O4 until the threshold limit of 2%, and performance of NSC20 was better than that of NFC20. Under the three-factor coupling, the strength corrosion resistance coefficient of nano-marine concrete was negatively correlated with the scouring erosion rate and the change rate of scouring erosion area, and positively correlated with the resistivity and the Cl- diffusion coefficient with the increase of corrosion age. When the corrosion age reached 70 days, the average scouring erosion rates of NSC20 and NFC20 were decreased 19.86% and 14.43%, respectively, compared with PC. The convective depth of concrete steadily decreased while its diffusive depth increased relative to concrete without scouring. Cl- binding was increased by 28.5%, 27.2%, and 21.4% for PC, NSC20, and NFC20, respectively. The high chemical activity of nano-SiO2 and nano-Fe3O4 promoted the mechanical performance and durability of concrete through improved density and homogeneity of chlorinated products and optimized the structure of the C-S-H/C-F-H gels in ITZ, as indicated by SEM-EDS observation, XRD, and DTG-DSC analysis. The coupling effects resulted in increasing volume of air voids and micro-cracks, as well as weak ITZ due to SA, which hindered scouring resistance development, as indicated by the MIP analysis.

Rainfall Erosivity in Peru: A New Gridded Dataset Based on GPM-IMERG and Comprehensive Assessment (2000–2020)

In soil erosion estimation models, the variables with the greatest impact are rainfall erosivity (RE), which is the measurement of precipitation energy and its potential capacity to cause erosion, and erosivity density (ED), which relates RE to precipitation. The RE requires high temporal resolution records for its estimation. However, due to the limited observed information and the increasing availability of rainfall estimates based on remote sensing, recent research has shown the usefulness of using observed-corrected satellite data for RE estimation. This study evaluates the performance of a new gridded dataset of RE and ED in Peru (PISCO_reed) by merging data from the IMERG v06 product, through a new calibration approach with hourly records of automatic weather stations, during the period of 2000–2020. By using this method, a correlation of 0.94 was found between PISCO_reed and RE obtained by the observed data. An average annual RE for Peru of 7840 MJ · mm · ha−1· h−1 was estimated with a general increase towards the lowland Amazon regions, and high values were found on the North Pacific Coast area of Peru. The spatial identification of the most at risk areas of erosion was evaluated through a relationship between the ED and rainfall. Both erosivity datasets will allow us to expand our fundamental understanding and quantify soil erosion with greater precision.

High-Resolution Real-Time Coastline Detection Using GNSS RTK, Optical, and Thermal SfM Photogrammetric Data in the Po River Delta, Italy

High-resolution coastline detection and monitoring are challenging on a global scale, especially in flat areas where natural events, sea level rise, and anthropic activities constantly modify the coastal environment. While the coastline related to the 0-level contour line can be extracted from accurate Digital Terrain Models (DTMs), the detection of the real-time, instantaneous coastline, especially at low tide, is a challenge that warrants further study and evaluation. In order to investigate an efficient combination of methods that allows to contribute to the knowledge in this field, this work uses topographic total station measurements, Global Navigation Satellite System Real-Time Kinematic (GNSS RTK) technique, and the Structure from Motion (SfM) approach (using a low-cost drone equipped with optical and thermal cameras). All the data were acquired at the beginning of 2022 and refer to the areas of Boccasette and Barricata, in the Po River Delta (Northeastern of Italy). The real-time coastline obtained from the GNSS data was validated using the topographic total station measurements; the correspondent polylines obtained from the photogrammetric data (using both automatic extraction and manual restitutions by visual inspection of orhophotos) were compared with the GNSS data to evaluate the performances of the different techniques. The results provided good agreement between the real-time coastlines obtained from different approaches. However, using the optical images, the accuracy was strictly connected with the radiometric changes in the photos and using thermal images, both manual and automatic polylines provided differences in the order of 1–2 m. Multi-temporal comparison of the 0-level coastline with those obtained from a LiDAR survey performed in 2018 provided the detection of the erosion and accretion areas in the period 2018–2022. The investigation on the two case studies showed a better accuracy of the GNSS RTK method in the real-time coastline detection. It can be considered as reliable ground-truth reference for the evaluation of the photogrammetric coastlines. While GNSS RTK proved to be more productive and efficient, optical and thermal SfM provided better results in terms of morphological completeness of the data.