Modeling Of Erosion Processes Research Articles

Methodical approach to determining the maximum permissible velocity of the gas flow with mechanical impurities using numerical modeling of erosion processes of the main technological elements of wellhead equipment

Long-term operation of gas fields is accompanied by changes in the stress-strain state of the productive reservoir, including irreversible processes of its destruction. The destruction of a productive reservoir is one of the reasons for the removal of mechanical impurities at the wellhead, abrasive wear, metal degradation, the appearance of defects in pipelines, equipment and wellhead binding. In order to avoid serious consequences from the development of defects due to the removal of impurities, various examinations are carried out using non-destructive testing methods. The need to monitor the actual condition of pipelines and wellhead equipment of wells operating the Cenomanian and Valanginian formations is due to the fact that during operation significant damage and destruction of the main elements of technological equipment may occur due to the removal of mechanical impurities, water, as well as the formation of hydrates, sand jams, etc., this can lead to serious economic losses, as well as the negative impact on the environment as a result of leaky connections and assemblies. Thus, in order to ensure reliable operation of producing gas wells in conditions of destruction of the bottom-hole zone of the well, it is necessary to choose a reasonable technological mode of operation, in which the risk of formation of sand and liquid plugs is reduced, and the negative impact of the removal of impurities on the condition of the equipment is minimized. Keywords: gas well; numerical modeling; bottom-hole zone; technological mode.

THE MAIN DIRECTIONS OF SCIENTIFIC RESEARCH AT THE DEPARTAMENT OF EROSION AND SOILPROTECTION: CURRENT STATE AND PROSPECTS OF DEVELOPMENT

The Department of Erosion and Soil Protection has developed the main scienti c directions - «Assessment of erosion processes in soils of various bioclimatic zones», «Study of the basics of sustainable land use» and «Ecological and economic assessment of soil and land degradation». It is proposed to develop both existing areas of scienti c research with a certain adjustment of their names and problems («Analysis and modeling of erosion processes in soils, including in the context of climate change», «Development of the concept of sustainable land use in the context of food security», «Ecology, economics and socio-demographic features of land use in the context of climate change and soil degradation»), as well as new directions that have some research history at the department - «Development of principles of soil protection», «Development of methodological foundations of land reclamation». e necessity of creating a holistic concept of soil protection is considered in particular detail. is concept should include both the formulation of legal (legislative and regulatory-methodological) principles of soil protection, and the de nition of criteria for assessing soils under which their protection can be carried out, and the development of soil protection systems ( rst of all, from the manifestation of erosion processes) in various bioclimatic and administrative-territorial conditions.

Reproduction and Analysis of Decay-Like Aging Development Induced by Interfacial Discharge in Composite Insulators

In the last decade, the decay-like aging phenomena of fiber reinforced plastic (FRP) core rods in composite insulators appeared frequently, and have significantly affected the safety of power transmission lines. However, the mechanism of its occurrence and development is still unclear. In this work, a method based on rod-housing interfacial discharge is proposed to artificially reproduce the occurrence and development of decay-like aging in FRP core rods under laboratory conditions. The aging process is explored under a high-humidity environment, where high-acidity and high-temperature conditions are also provided by interfacial discharge. The micro- and macro-scopic structures, physicochemical properties and leakage currents of FRP samples are characterized during a 1000-hour aging process. The laboratory aged samples resemble the decay-like phenomena in on-site insulators, indicating the effectiveness of this method. Experimental results show that interfacial discharge can trigger the decomposition of epoxy resin in FRP core rods, leading to exposure of glass fibers. Electrical erosion slows down as aging time increases, and the erosion rate is positively related to the porosity of core rods. Further discussion indicates that erosion is impeded by glass fibers in the surface aging layer due to its high thermal and chemical stability, and a three-stage erosion process model is proposed. Finally, a semi-empirical model is proposed to describe this aging process, in which the influence of core rod porosity is taken into account. This work provides an effective laboratorial method to reproduce the decay-like aging of composite insulators, and reveals its erosion process and the underlying mechanism.

Effect of different underlying surfaces on hydraulic parameters of overland flow

The estimation of hydraulic parameters is the basis for establishing soil erosion models. However, the underlying surfaces greatly influence the hydraulic parameters of the overland flow. Since sediment flow and slope surface resistance interact, exploring the mechanism of overland flow movement in relation to different underlying surfaces is essential. A potential relationship between hydrodynamic parameters and slope gradient and flow discharge was investigated by carrying out overland flow experiments, which used four types of non-erosion slope surfaces (stem cover, brown soil, frozen soil, and organic glass), four slope gradients (3°, 6°, 9°, and 12°), and four flow discharges (0.35, 0.45, 0.55, and 0.65 L s–1). The results showed that the hydraulic parameters (i.e., mean flow velocity, flow depth, Froude number, Reynolds number, shear stress, drag coefficient, stream power, and unit stream power) differed with the increased slope gradients and flow discharges. The mean flow velocity of the stem cover slope was lower than that of the frozen soil slope, brown soil slope, and organic glass slope by 33%, 40%, and 50%, respectively. The stem cover slope drag coefficient was higher than the frozen soil slope, brown soil slope, and organic glass slope by 201%, 323%, and 630%, respectively. The critical flow states of the underlying surface were different under different slope gradients and flow discharge conditions. The flow on frozen soil slopes was mainly laminar and transitional, while the other three were transitional. These results help us understand the hydrodynamic mechanisms of the sediment transport process during overland flow. The results of the study provide a scientific basis for understanding the hydrodynamic mechanism of the dynamic changes of the sediment transport on the slope, deepening the understanding of the soil erosion mechanism and improving the prediction accuracy of the soil erosion process model.

Magnetic susceptibility of the slope soils for predicting of agronomic characteristics

The article is related to the study of the localization of agronomic heterogeneities of the soil distributed on slopes. To study this important agricultural areas, we usedthe mathematical modeling of erosion processes and the survey of the magnetic susceptibility of the arable horizon of the soils. The experiment design includes the typical chernozemof the slope.The soil sampling was performed according to DSTU 4287:2004, determination of organic carbon content according to DSTU 4289:2004, and determination of statistical indicators using Statistica®. The visualization of the study results was carried out in the QGis software. Magnetic susceptibility (MS) was measured using a KLY-2 magnetometer. Modeling of soil erosion processes involved USLE universal soil loss equation. A 1:10,000 topographic map was adopted as the topographic basis. The research territory is the fields of the National Biotechnological University (V.V. Dokuchaev KhNAU) on the southern outskirts of the city of Kharkiv. The 70 soil samples were collected from the arable layer (horizon A). Due to the course of water erosion processes, a long-term soil washout and a widespread complex spatial complex of washed-out soils took place on the site, which is a typical case for eroded sloping lands of the Forest Steppe. In non-eroded watersheds (in the north-western direction), typical heavy loamy medium-humus chernozems are developed. Sampling was carried out using an irregular grid, the sampling density was about 5 samples per hectare.We detected that mathematical modeling of erosion processes can be used to predict the location of inhomogeneities in the agronomic properties of the ground cover of sloping lands. However, given the shortcomings of the main models of potential soil losses associated with the alternation of zones of erosion and deposition require to clarify and verify the obtained results. Hence, we propose to apply the statistical characteristics of the spatial distribution of values of the magnetic susceptibility of the soil. The most important parameters are the average values and coefficient of variation of MS.

Magnetic susceptibility of inclined soils and its relationship with some agronomic indicators

The modern agricultural complex requires the use of new methods for determining soil characteristics for adequate information support of the latest technologies, which is often impossible to provide using conventional methods. The purpose of the study is to identify the informative value of magnetometric methods in determining slope processes that regulate the use of certain measures to increase soil fertility and protect soils from erosion. The study was conducted on inclined agricultural landscapes of the Kharkiv region. This study used a KLY-2 Kappabridge (Czech Republic) and an Ohaus 403 laboratory scale to determine magnetic susceptibility. The selected soil samples, in accordance with the accepted methods, were brought to an air-dry state under normal conditions. Soil sampling was conducted from a layer of 0-20 cm. Visualisation of the study results and determination of potential soil losses (USLE model) was performed in the QGis programme. The correlation of magnetic susceptibility on simple and complex slopes was analysed. It was established that on simple slopes, the value of the magnetic susceptibility of the soil has a high value of this indicator with the content of physical clay and organic carbon. Therewith, there is a high degree of connection of this indicator with the results of mathematical modelling of erosion processes (USLE). For complex sections of slopes, the method is correct only for transeluvial landscapes, while for accumulative landscapes, the mentioned connection disappears. The correlation coefficient in the humus content – magnetic susceptibility pair also decreases. This is due to the alternation of washout–accumulation zones and exits of soil-forming rocks in runoff basins, the existence of which is not provided for by the procedure for applying the USLE model of potential soil losses. The use of soil MS data has a high potential for the localisation of soil inhomogeneities associated with the differentiation of humus content and granulometric composition

Effects of sediment characteristics on the sediment transport capacity of overland flow

The transport of sediments is a crucial part of soil erosion. Accurately calculating the sediment transport capacity is key to the construction of soil erosion process models. Research on Tc has focused mainly on the dynamics of a single particle of sediment and hydraulic variables. There have been few studies of the impact of soil aggregates on the Tc. To clarify how sediment characteristics, including those for single particles and aggregates, affect the Tc of overland flow with no raindrop import, flume experiments were implemented at slope gradients varying from 5.24% to 26.80% and flow discharges ranging from 0.68 to 5.41 × 10−3 m2 s−1. The experimental materials were five typical soils in China. The results indicated that the correlation between the measured Tc and sediment mechanical composition indexes of the five soils was indistinctive in this study. The sediment settling velocity with aggregates has a significant correlation with the measured Tc. New equations, including for the sediment settling velocity with aggregates ωud75, were established to calculate the Tc. The empirical equation that included ωud75, slope gradient and unit discharge performed greatly in predicting Tc (R2 = 0.93, NSE = 0.90). ωud75 can effectively improve the calculation accuracy of Tc. The new equation including flow and sediment properties obtained through dimensional analysis performed well in predicting Tc (R2 = 0.99, NSE = 0.91), and the calculation accuracy was better than that of the empirical model derived in this study. These findings indicate that the sediment settling velocity is an important variable in the equation for predicting sediment transport capacity of overland flow.

Modeling of erosion processes in open channels

Objective. The aim of the study is to model erosion processes in open channels.Method. A stochastic approach is applied to the calculation of parameters and the construction of models of individual stages of the erosion process: disruption, weighing and transport of eroded soil particles by a turbulent flow. Result. A technique has been developed for predicting the general erosion of riverbeds and canals, composed of homogeneous and heterogeneous non-cohesive soils. Approbation of the developed technique on the material of laboratory and field studies confirmed its satisfactory accuracy in a wide range of hydraulic conditions and soil granulometric compositions. Conclusion. The principles of developing a model of erosion processes in open channels, the modular structure of the calculation algorithms and programs compiled on its basis, allow us to continuously improve the methods for calculating individual parameters of the erosion process and make adjustments to the corresponding modules of algorithms.

Methodology for assessing the danger of erosion and formation of soil protection agro-landscapes

Purpose. On the basis of an in-depth analysis of the erosion safety of the soil cover of Ukraine, to determine the theoretical and applied principles of the formation of an agrolandscape with guaranteed soil protection, mainly by engineering methods. Methods. System comparative analysis of erosion hazard. Mathematical modeling of erosion processes. Physical simulation of anti-corrosion protection. Results. The main causes of progressive soil erosion in Ukraine have been revealed. Classified distributed soil erosion by types and species. The main reason for the development of erosion processes and the imbalance of modern agricultural landscapes of Ukraine, which is excessive plowing of the territory and agricultural lands, has been revealed. Annual erosion losses from arable lands of Ukraine are indicated. The main degradation processes of the soil cover have been identified. The main problems in land use and land protection, which are not solved and become chronic, are formulated. Generalized negative ecological consequences of soil erosion of the chernozem habitus. It has been proven that arable land is the main element of the entropy of “chaos” in the landscape. Algorithms for the construction of soil protection agrolandscape are formulated. The ability to use the hydromechanical model has been proven Ts. E. Mirtskhulava, which we have moderated for the assessment of erosion danger in the formation of agricultural landscape structures mainly by engineering methods, for a certain probability of manifestation of erosion danger and individual factors of soil erosion. Conclusions 1. The soil cover of the Earth is degraded by almost 100%, the greatest “weight” among degradation processes is occupied by the processes of water (36%) and wind (28%) erosions. 2. One of the most significant destabilizing factors is arable land. When natural vegetation is destroyed, the soil is destroyed as a result of a sharp increase in the direct absorption of solar radiation. 3. A reliable method of protecting soils from erosion is an agrolandscape – an engineering structure (structure) that must be designed and built mainly by engineering methods on a calculated and quantitative basis, which requires the presence of appropriate mathematical models verified in every way, those processes that determined the stability and productivity of lands. The “zero” cycle is the basis of the construction of the agro-landscape is the anti-erosion protection system. 4. For the formation of anti-erosion protection in the agricultural landscape, a mathematical model of erosion is necessary as a calculation quantitative base, preference should be given to theoretical models that adequately and physically conditionally describe natural processes. Keywords: soil erosion and degradation, agricultural landscape, mathematical models of erosion, erosion hazard.

Coupling Remote Sensing and GIS with KINEROS2 Model for Spatially Distributed Runoff Modeling in a Himalayan Watershed

Excessive runoff and high soil erosion rate are the critical problems in the Himalayan terrain, mainly due to rugged topography and high intensity rains. Accurate quantification of runoff and erosion is thus of paramount importance for taking appropriate measures to sustain the soil productivity in the Himalayan watersheds. Distributed, process-based hydrological and erosion models are ideal for this purpose. However, model parameterization in the rugged, inaccessible and thus generally a data scarce Himalayan watershed is a major challenge. The present study primarily investigates the applicability of kinematic runoff and erosion model (KINEROS2) model in a Himalayan watershed besides exploring the potential of satellite remote sensing and GIS in spatially distributed runoff modeling. The KINEROS2 model, is an event-based, distributed, water and erosion process model. It discretizes the watershed into a mosaic of planes and channels based on topography. The runoff is estimated for each plane which eventually flows to adjacent channel and is then routed to estimate the total runoff at the watershed outlet. Remote sensing is primarily used for model parameterization, i.e., characterizing the individual planes and channels. Optimized digital elevation model and fine-scale land-use/land-cover information are generated using high-resolution panchromatic and multi-spectral optical and microwave satellite imagery. The resulting data on near-surface soil moisture from radar imagery (ENVISAT ASAR) calibrated the initial soil moisture in the model, whose performance is evaluated using root mean square error and Nash–Sutcliffe that reveals that KINEROS2 model works quite well in a small Himalayan watershed. The sensitivity analysis indicates that saturated soil hydraulic conductivity is the most sensitive parameter influencing the runoff compared to Manning’s coefficient and initial soil moisture. The model output is also used for validating the remote sensing and geographical information system (GIS) based hydrologic response units delineated in a previous research study. The study highlights that the coupling of remote sensing and GIS with process models, such as KINEROS2, can provide valuable information in planning sustainable watershed management practices in the Himalayan watersheds.

Удосконалення системи охорони ґрунтів від ерозії в умовах змін клімату

Goal. To show the existing climatic trends, their impact on erosion processes and improve the soil protection system. Methods. Field, laboratory, cartographic, statistical, geoinformation analysis, mathematical modeling. Results. The manifestation of global climate change in Ukraine is an increase in average air temperatures and the sum of active temperatures, increasing aridity and changes in air and precipitation in the direction of increasing the heterogeneity of their distribution throughout the year and increasing the share of heavy rains and showers. That leads to an increase in the erosion risk, which requires a revision of the existing system of soil protection measures and stricter requirements for their application. A set of agro-technical and organizational measures, which consists of optimizing the structure of crop rotations, removing the most erosive dangerous areas from arable land, and applying soil-protective agricultural techniques, allows in most cases to reduce the level of soil losses to regulatory values. Among the methods of basic tillage, preference should be given to chiseling, which makes it possible to store plant remains on the soil surface. For erosion research, it is advisable to take into account the part of the surface covered with plant debris or protected from the wind by reclamation plantations. It is also promising to use non-contact methods, such as magnetometry. Mathematical modeling of erosion processes, which is a necessary component of the development of erosion protection systems, requires the revision of the applied precipitation parameters following climate change. Conclusions. Improving the system of soil protection from erosion in the context of climate change should be carried out consistently on each of the components of the system, starting with the optimization of crop rotation and the use of soil protection measures. Despite the generally positive experience of using soil protection agrotechnical measures on lands with high erosion risk to prevent erosion, they should be used in combination with hydrotechnical and agro-forestry reclamation measures, which should be carried out at the national level.

Comparative study on different sediment transport capacity based on dimensionless flow intensity index

Sediment transport plays a vital role in the development of soil erosion process models. The primary purpose of this study is to establish new sediment transport capacity formulas and evaluate their applicability to sediment. In this study, we collected three different soil types from Loess Plateau. Simulated sediment transport experiments were carried out in indoor flumes with energy gradients ranging from 6.9 to 20.8% and unit flow discharge rates ranging from 0.00014 to 0.00111 m2 s−1. We found an exponential relationship between sediment transport capacity, energy gradients, and unit flow discharge rates. The sediment transport capacity increased with increasing energy gradient and unit flow discharge, and the unit flow discharge had a more significant influence on sediment transport capacity compared with energy gradient. We used each composite force predictor and measured the sediment transport capacity according to the nondimensional principle, and the resulting data corresponded to different soils distributed in zones, as sediment transport capacity is controlled by a critical starting condition. After including soil clay particle content and volume sediment content in our formula, we were able to derive an accurate equation for calculating sediment transport. Among the dimensionless composite force predictors, the dimensionless effective stream power was the most reliable predictor. The sediment transport capacity and effective stream power were related exponentially (R2 = 0.953).

On the Issue of Research of Information Support of Sustainable Agricultural Landscapes Formation

Purpose. To characterize the methodological approaches that we develop in the formation of a system of information support for the creation and maintenance of the functioning of modern sustainable agricultural landscapes and to show the results of their implementation on the example of the territory of some agricultural enterprises of the Kharkiv region. Methods. Cartographic, geoinformation analysis, calculation, statistical and mathematical. Results. Some results of the work of the collective on the issues of information support for the creation and maintenance of the functioning of modern sustainable agricultural landscapes. Namely, verification of erosion models, studies of the functionality of shelter belts, the formation of an agroeconet (an extensive network of natural and quasi-natural landscapes) on agricultural land massifs, which ensures the maintenance of stable functioning of meso and macrolevel agrolandscapes, as well as the experience of using magnetic prospecting methods to verify the results of mathematical modeling of erosion processes. Conclusions. A number of methodological approaches to information support of the formation of sustainable agricultural landscapes in the natural and socio-economic conditions of Ukraine have been developed. They relate to the functioning of anti-erosion measures of permanent action, the processes of modern transformation of agro-landscapes, the ecological impact of erosion processes on the environment. The connection between the length of forest belts per unit of arable land and soil erosion is shown. A methodical approach has been developed to estimate the amount of soil washed away from arable land and to calculate the measures necessary to eliminate its harmful effects on the environment.

Modelling of erosion processes associated with rainfall-triggered lahars following the 2011 Cordon Caulle eruption (Chile)

In this work we investigate the sheet and rill erosion process as a possible lahar initiation mechanism in two catchments located in Villa la Angostura, Argentina (Southern Andes), in association with the 2011 eruption of Cordón Caulle (Chile). A few days after the climactic phase of the eruption, several lahar events occurred in Villa la Angostura where 15 cm of tephra mantled the slopes. The physically based model LISEM (openLISEM, 2013a, b) was applied to two small catchments where sheet and rill erosion of tephra deposits was observed. Model input parameters related to vegetation, soil surface and infiltration were obtained from field measurements, geotechnical tests and the literature. A total of 20 scenarios were simulated using a range of values of rainfall intensity and duration and hydraulic conductivity; only 16 of these scenarios resulted in erosion. Results show that hydraulic conductivity (Ks) and rainfall intensity significantly affect the runoff volume, with the smallest Ks (i.e. the tephra deposits associated with the largest fraction of fine ash) being associated with the largest eroded volumes and the largest discharges of water and sediment. The scenarios with the highest hydraulic conductivity did not show erosion for any modelled rainfall intensity. Nonetheless, we conclude that sheet and rill erosion were not the principal mechanism for rain-triggered lahars associated with the Cordón Caulle eruption, but mostly shallow landslide and similar erosion mechanisms contributed to lahars in Villa La Angostura. In fact, the eroded volumes calculated with LISEM are significantly smaller than the volume calculated with shallow landslide models for the same catchments (TRIGRS).

Modeling of erosion processes in the structural materials of spacecraft under irradiation by ion beams with a wide energy spectrum. Part 2 (comparison of experimental and calculated results)

The calculations of the coefficients of sputtering, mileage and energy release of the implanted ions are carried out. The results are compared with experimental data.

Assessment of open source digital elevation models (SRTM-30, ASTER, ALOS) for erosion processes modeling

The relief has a major impact on the landscape`s hydrological, geomorphological and biological processes. Many geographic information systems used elevation data as the primary data for analysis, modeling, etc. A digital elevation model (DEM) is a modern representation of the continuous variations of relief over space in digital form. Digital Elevation Models (DEMs) are important source for prediction of soil erosion parameters. The potential of global open source DEMs (SRTM, ASTER, ALOS) and their suitability for using in modeling of erosion processes are assessed in this study. Shumsky district of Ternopil region, which is located in the Western part of Ukraine, is the area of our study. The soils of Shumsky district are adverselyaffected by erosion processes. The analysis was performed on the basis of the characteristics of the hydrological network and relief. The reference DEM was generated from the hypsographic data(contours) on the 1:50000 topographical map series compiled by production units of the Main Department of Geodesy and Cartography under the Council of Ministers. The differences between the reference DEM and open source DEMs (SRTM, ASTER and ALOS) are examined. Methods of visual detection of DEM defects, profiling, correlation, and statistics were used in the comparative analysis. This research included the analysis oferrors that occurred during the generation of DEM. The vertical accuracy of these DEMs, root mean square error (RMSE), absolute and relative errors, maximum deviation, and correlation coefficient have been calculated. Vertical accuracy of DEMs has been assessed using actual heights of the sample points. The analysis shows that SRTM and ALOS DEMs are more reliable and accurate than ASTER GDEM. The results indicate that vertical accuracy of DEMs is 7,02m, 7,12 m, 7,60 mand 8,71 m for ALOS, SRTM 30, SRTM 90 and ASTER DEMs respectively. ASTER GDEM had the highest absolute, relative and root mean square errors, the highest maximum positive and negative deviation, a large difference with reference heights, and the lowest correlation coefficient. Therefore, ASTER GDEM is the least acceptable for studying the intensity and development of erosion processes. The use of global open source DEMs, compared with the vectorization of topographic maps,greatly simplifies and accelerates the modeling of erosion processes and the assessment of the erosion risk in the administrative district.

Erosion resistance potential as a soil erodibility characteristic based on energy approach

The ambiguity of existing methods encouraged researchers to search for more adequate approaches for the determination of soil erodibility. In the paper, based on the energy approach to soil erosion analysis, we have proposed a physically justified characteristic of soil erodibility as the potential of erosion resistance equal to the energy spent on the destruction and removal of a unit of soil mass in the places of its natural occurrence. The device and method of measuring the potential of erosion resistance in the field were described. The exponential character of the dependence of the erosion resistance potential on the volume moisture for light-gray and dark-gray forest soils of central region of Russia was experimentally revealed. It was shown that as the soil was moistened, the value of erosion resistance potential tended to a certain limit. Modelling of erosion processes on the basis of the proposed erosion resistance potential can allow describing erosion properties depending on the initial soil moisture and evaluating them at any time during the growing season.

Кількісна оцінка ерозійної небезпеки сільськогосподарських угідь

The largest and practically non-renewable losses of erosion in all sectors of the economy undergoes agrarian sphere. The area of land damaged by water erosion in Ukraine reaches 33.3% or 13.3 million hectares, of which 4.5 million hectares are medium and strongly ground, of which 68 thousand hectares completely lost the humus horizon. The reasons for the acceleration of erosion processes in Ukraine are the mass ignoring of the simplest agrotechnical anti-erosion measures, the imperfection of the land management organization of the territory to provide elementary anti-erosion protection, underestimation of the role of wild forest belts, ineffective use of funds aimed at preventing erosion, resulting in degradation processes lately unprecedented. High degree of cultivation of agricultural land and excessive saturation of crop rotation with crop rotation against the background of non-compliance with the basic provisions of a set of measures to increase and maintain soil fertility is a direct way to the destruction of soil cover as a basis for the existence of life on our planet. The quantitative estimation of water erosion involves two systems of evaluation criteria: the actual soil erosion and the potential danger of erosion at a certain level of probability of the effects of erosion factors (the world experience in the organization of anti-erosion protection indicates that it is sufficient to calculate 10% security). To update the outdated data on soil erosion in Ukraine, it is necessary to conduct a repeated continuous survey of soil cover on a modern methodological basis, which requires significant financial costs. However, it is possible to assess the erosion hazard using mathematical models of erosion, in particular the Water Erosion Prediction Project (WEPP) model, which provides information on the intensity and tension of erosion processes and the determination of the magnitude of possible erosion losses in the soil. WEPP is a physically grounded model that allows the modeling of erosion processes of agricultural lands located on small water catchments (up to 250 hectares). The model is based on mathematical equations describing physical processes of soil erosion and hydrology of erosion runoff. In this case, the catchment area, according to its relief, is divided into elementary units - slopes and watercourses. The model allows you to trace the routes of drainage and flushing along the elements of the relief up to the exit of the catchment. Simulation can be carried out in two modes: in the mode of long-term modeling and in mode of modeling of a single shower. The input data for the model are data on the terrain, the characteristics of the catchment soil, types of cultivating soil and agricultural vegetation on its fields, parameters characterizing the climatic conditions of the terrain. Two series of forecast calculations were conducted: the first one was for the conditions of the existing land placement, the second one for the case of implementation of the project of soil protection of the territory. For this purpose, in both cases, the preferred lines of the drain lines were determined, for each runoff line, soil erosion loss calculation using the WEPP model was performed, after which regularization and interpolation of the obtained data were performed and erosion hazard maps for each case were constructed. Quantitative estimation of two series of forecast calculations for the conditions of existing land placement and in the case of implementation of the project of soil protection of the territory using WEPP erosion model and specialized software showed that in the event of a 10% rainstorming of equipment, the territory of forest bands and drainage facilities significantly reduces erosion danger, even in the black pair.

Sediment selective behaviors of colluvial deposit materials on steep slopes and under heavy rainfall conditions in southeastern China

Characterizing sediment selectivity during transport will improve understanding of soil erosion processes, but few studies have focused on steep slopes and soil with loose, coarse material. This study examined colluvial deposits, which contain loose materials with large amounts of coarse particles. These soils were subjected to simulated rainfall in a 5 m2 (5 m by 1 m) box at heavy rainfall intensities (1, 1.33, 1.67, 2, and 2.33 mm min−1) and on five steep slopes (20°, 25°, 30°, 35°, and 40°). During the experiments, the particle size of the eroded material gradually coarsened, then stabilized and often showed short-term fluctuations as the rainfall progressed. During interrill erosion processes, the sediment became enriched with finer particles because of the low runoff energy of interrill flow; the dominant transport mechanism was the suspension-saltation transport of sediment with a grain size finer than 0.537 mm. However, the sediment was coarser after rill development than before, and increased stream power meant that bed-load transport by rolling of the larger sediment grains (coarser than 0.957 mm) became an increasingly important mechanism; bed-load transport also increased with rainfall intensity, so the particle-size distribution for high-intensity rainfall resembled that of the original soil. Finally, during rill erosion processes, rill bank collapse occured and the original soil contained coarse, heavy particles that could more easily be rolled on steep slopes. These factors could increase the relative importance of bed-load transport. The results of this study have important implications for assessment and modeling of erosion processes in disturbed soils with large amounts of coarse particles.

Landscape‐scale modelling of erosion processes and soil carbon dynamics under land‐use and climate change in agroecosystems

SummarySoil organic carbon (SOC) sequestration and soil redistribution are linked to soil properties, land use, farming system and climate. In a global‐change context, landscape and climate changes are expected and will most probably have impacts on changes in the soil. Soil change was simulated from 2010 to 2100 in an 86‐ha hedgerow landscape under different scenarios of landscape and climate changes. These scenarios combined contrasting land uses, hedgerow networks and climates. Two models were combined to evaluate the impact of these scenarios on soils: LandSoil, a soil redistribution model, and a SOC model based on RothC‐26.3. A soil thickness of 105 cm was considered. The results indicate that the main factor influencing soil degradation was land‐use change: when compared with the baseline business‐as‐usual landscape, the landscape with the most intensive agricultural systems had the greatest soil erosion (+0.26 t ha−1 year−1) and reduced mean SOC stocks (−17 t ha−1 after 90 years). The second significant factor was climate change, followed by hedgerow network density. Sensitivity to climate change differed between landscapes, and the most sensitive were those with continuous winter wheat. The results indicate that a hedgerow landscape is well adapted to protect soil (regarding carbon storage and soil erosion) in a context of climate change. However, this type of landscape is highly sensitive to cropping intensification and should be protected.