Water Erosion Risk Research Articles

The Slope Association Type as a Comparative Index for the Evaluation of Environmental Risks

The topography is one of the determining site characteristics, of which the slope inclination is significant for natural science aspects, including the estimation of water erosion risk and as a criterion for agricultural subsidies. The slopes within an area vary greatly and occupy very different proportions of the area. Algorithms that take this heterogeneity into account were developed in the 1970s with the medium-scale agricultural site mapping (MMK). It also contains the slope association types (SAT, in German: “Hangneigungsflächentyp”), which classifies different slopes and summarizes them as one value per reference area. The SAT can be used across various scales and different targets. Applicability is given to soil and water conservation tasks, administrative tasks as field selection or agricultural subsidies, and over a wide range of scales from small catchments areas to whole landscape analyses. Thus, one value on an area basis characterizes an important topographic factor.

Water Erosion in the Moulouya Watershed and its Impact on Dams' Siltation (Eastern Morocco)

Abstract. The Moulouya watershed presents high risks of water erosion. The dams built on this river lose each year, by siltation, a volume of water of about 10 M m3 (Lahlou, 1994). This worrying rate shows that water erosion can hinder the socio-economic development of the basin if soil protection and siltation measures are not taken. This study defines the areas most threatened by water erosion to protect them as a priority. Using a GIS and the Universal Earth Loss Equation (USLE), we mapped soil losses. The adopted model determines soil loss from erosivity of rainfall, soil erodibility, inclination and slope length, soil cover, and erosion control practices. The possible origins of the deposits alluviating the dams are related to the products of alteration of the Secondary's carbonate formations and the Tertiary and Quaternary formations. The modalities of the transport of deposits of banks of the network of Moulouya are mainly by a suspension. The specific degradation in the Moulouya watershed is estimated at 214 t/km2/year. Precipitation intensity, steep slopes and deforestation are responsible for these losses.

Mapping the Risk of Water Soil Erosion in Larrodrigo (Salamanca, Spain) Using the RUSLE Model and A-DInSAR Technique

The quantification of soil loss are studies driven by the importance of soil as a resource and are mainly due to risks of laminar and/or runoff water erosion. These problems directly affect the daily life of the population and serve as predictors of environmental effects. In this work, the quantification and calculation of the sheet water erosion caused mainly by rainfall has been carried out in a study area located in the municipality of Larrodrigo (Salamanca, Spain), based on the simultaneous application of the RUSLE model with GIS techniques. Thematic cartographies have been generated to determine soil loss in Tm/Ha/year and mm/year based on the use of parameters of the physical environment (lithology, rainfall, slopes…) where the erosive risk is quantified and its applicability to the study area by spatio-temporal extrapolation techniques. Simultaneously, the use of the A-DInSAR technique was implemented to calculate average ground deformation velocities in mm/year associated with water erosion. Two sectors with greater vulnerability to water erosion have been detected within the area of interest: one of them called main, which corresponds to the slopes near the Larrodrigo stream, with soil losses showing values of 0.3- > 12 mm/year, and a secondary sector belonging to the tributaries or channels derived from the mainstream with values of 0.3- > 12 mm/year. This type of study makes it possible to manage and organise human support practicesin order to subsequently establish measures that can prevent, mitigate and/or correct those areas with the greatest damage.

Using a modified PAP/RAC model and GIS-for mapping water erosion and causal risk factors: Case study of the Asfalou watershed, Morocco

Our work focuses on the assessment of trends, erosion states and causal risk factors for soil erosion of the Asfalou watershed through the use of the Priority Actions Program/Regional Activity Center (PAP/RAC). This qualitative study model for water erosion makes it possible to assess susceptibility and determine potential fragile areas in order to diagnose the state of soil degradation. We adopted the PAP/RAC crossed matrices, the geographic information system (GIS) and remote sensing (RS) to develop the classical modelling. This method is based on three main approaches: predictive, descriptive and integration. Introducing soil types, slope length (LS) and climatic factors into our model, including rainfall erosivity (R), slope exposure, soil moisture index (SMI) and land surface temperature (LST), improved the reliability of our model. The correlation analysis identified these factors that explain erosion states and the risk of soil erosion. The coefficients of determination (R2) of the various erosive states resulting from the modified PAP/RAC approach explain respectively 98.30%, 77% and 49.3% of the observed variability of the erosive states. These factors provide information on the current state of soil degradation depending on the degree of influence of the different factors that control erosion. The descriptive approach has shown that soil loss manifests itself in different forms, whether for sheet erosion (L) and ravines (C1) successively affecting 79.95% and 17.84% of the land. The integration approach identifies factors and areas requiring intervention to counter the effects of soil erosion in the Asfalou watershed effectively and sustainably.

Vegetation greening partly offsets the water erosion risk in China from 1999 to 2018

Soil erosion by water is a major threat to land degradation. The United Nations Decade on Ecosystem Restoration 2021–2030 calls for massive ecosystem restoration to address land degradation impacts. Due to the implementation of large-scale soil and water conservation programs in China (i.e., the Grain for Green Program), the area covered by vegetation has increased. Climate change may exacerbate soil erosion risk, while vegetation greening may alleviate this risk. This work aims to assess China's water erosion risk over the past two decades since the implementation of the Grain for Green Program (1999–2018) and explore the relative importance of precipitation and vegetation on erosion risk dynamics. An integrated method was developed using the Revised Universal Soil Loss Equation and the Pressure-State-Response model. An indicator contribution index was applied to detect the impacts of soil cover and management (C) and rainfall erosivity (R) on risk changes. The results showed that China's water erosion risk had a decreasing trend (23% between 1999 and 2018), especially in areas with middle and high state indicator values. R contributed more than C in northern China, whereas the opposite occurred in southern China. The contribution of R decreased while that of C increased. Vegetation greening partly offset the pressure from climate change. Overall, this work highlights the importance of vegetation recovery in reducing water erosion.

Mapping soil erosion–prone sites through GIS and remote sensing for the Tifnout Askaoun watershed, southern Morocco

The Moroccan High Atlas is very sensitive to soil erosion due to its steep slopes, torrential rains, and degraded plant cover. The degradation of fertile soils in this mountainous watershed influences negatively upon agricultural productivity. The objective of this study is to quantify soil erosion in the Tifnout Askaoun watershed in southern Morocco. The Revised Universal Soil Loss Equation (RUSLE), the geographic information system (GIS) techniques, and the Tropical Rainfall Measuring Mission (TRMM) data were adopted for mapping the annual rate of soil loss in this watershed area of around 1488 km2. The spatial distribution of annual soil erosion rates was obtained by integrating the geo-environmental variables into a GIS. These variables are the rainfall erosivity (R) generated from the TRMM data, the soil erodibility factor (K), the length and slope inclination (LS), the vegetation and management factor (C), and the practice support factor (P). Results reveal an average annual soil erosion rate of 14.44 t/ha/year and a good correlation with the slope length and steepness factor (r = 0.72) and in a lesser extent with the rainfall erosivity factor (r = 0.63). The sub-catchments of the study area were mapped and grouped into five classes of vulnerability to soil erosion risk, with results indicating that the Toubkal sub-catchment is the most threatened by water erosion risk as reflected by an average erosion rate of 48.05 t/ha/year. Approaches and results from this study, which was conducted between 2017 and 2019, may benefit researchers and decision-makers concerned with soil management primarily in mountainous areas where soil degradation impacts the activities of the rural population.

Using RUSLE and GIS for the soil loss assessment in arid regions: The case of the Ain Sefra catchment in the Ksour Mountains, Algeria

The loss of soil quality due to erosion is a global problem, particularly affecting natural resources and agricultural pro-duction in Algeria. In this study, the Revised Universal Soil Loss Equation (RUSLE) is applied to estimate the risk of water erosion in the Ain Sefra arid watershed (Algeria). The coupling of this equation with Geographic Information Systems (GIS) allows to assess and map the soil loss rates. The land erosion is influenced by many control variables, such as the topographic factor of the terrain and the length of slope (LS factor), rainfall erosivity (R factor), sensitivity of soil to erosion (K factor), presence of vegetation (C factor) and the anti-erosion cultivation techniques (P factor). To calculate the average annual soil loss, these five factors were considered and multiplied in the RUSLE Equation. The result shows that the aver-age rate of soil loss is estimated at about 5.2 t·ha–1·y–1 over the whole watershed. This study is the first of its kind in the region and aims to assess the soil loss caused by water erosion processes in this arid zone. Consequently, it is essential to take real intervention measures in these upstream areas in order to combat this scourge, based on priorities ensuring the sustainable management of natural resources in the study area.

Prioritizing soil conservation measures based on water erosion risk and production and bio-energy losses in peninsular South Indian states

Critical soil erosion risk areas in peninsular southern Indian states were identified through integration of biophysical and productivity loss following a robust scientific procedure (weighted average). Biophysical priority as a function of difference between soil erosion and corresponding soil loss tolerance values at a given location were redefined into three soil erosion risk classes, namely Low, Mid and High. Cumulative productivity losses, due to water erosion, of major crops grown in the area were also prioritized and an overall harmonization was made by integrating the two datasets. Analysis revealed that Kerala is suffering the most with a loss of 4.8 q ha−1 followed by Karnataka (2.7 q ha−1), Andhra Pradesh (2.1 q ha−1) and Tamil Nadu (1.8 q ha−1) which is equivalent to annual production loss of about 2.31 M t of cereals, 0.83 M t of oilseeds and 0.52 M t of pulses due to water erosion. As per the weighted methodology, all states fall under Mid Priority class since the weighted values of these states are less than or equal to country’s weighted value (16 t ha−1), but higher than half of the difference (i.e. 8 t ha−1) between weighted India value and lowest non-priority value (zero t ha−1). The energy loss in terms of aboveground biomass of all major crops has been estimated as 152 tera joules. The estimated production and energy losses due to soil erosion would greatly help in taking informed decisions for implementing appropriate conservation measures at local, regional and global level as the problem of soil erosion has not been addressed in an integrated manner so far.

Cover Crop Contributions to Improve the Soil Nitrogen and Carbon Sequestration in Almond Orchards (SW Spain)

Almond (Prunus dulcis Mill. [D.A. Webb]) is the third most widely spread crop in Spain and has traditionally been cultivated in marginal areas and shallow soils under rainfed conditions. However, it recently has been progressively introduced in flat irrigated areas. The implementation of cover crops in the inter-rows of woody crops has been proven as a suitable strategy to reduce the runoff and soil erosion but they also can boost soil quality and health. A field experiment was conducted during two-monitoring seasons to examine the soil nitrogen and carbon sequestration potential of three seeded cover crops [barley (Hordeum vulgare L.), hairy vetch (Vicia villosa Roth), and a mixture of 65% barley and 35% vetch] and a control of spontaneous flora in irrigated almond orchards (SW Spain). Here, we show that barley provided the highest biomass amount, followed by mixture covers, vetch, and the control treatment. Also, vetch covered the soil faster in the growing stage, but its residues were decomposed easier than barley and mixture treatments during the decomposition period after mowing, providing less soil protection when the risk of water erosion with autumn rainfall is high. On the other hand, vetch improved soil nitrate content by over 35% with respect to barley and mixture treatments at 0–20 cm soil depth throughout the studied period. In addition, a greater carbon input to the soil was determined in the barley plot. That is, the mixture and barley cover crops had higher potential for carbon sequestration, augmenting the soil organic carbon by more than 1.0 Mg ha−1 during the study period. Thus, taking into consideration the findings of the present experiment, the establishment of a seeded cover crop would be more advisable than spontaneous flora to mitigate soil erosion, enhancing soil fertility and carbon sequestration in irrigated almond plantations in Mediterranean semi-arid regions.

Risks of Water Erosion in the Zubaidi Basin According to the Methodology of (PAP / CAR 1998)

The science of geomorphology is no longer a science based on description and classification of terrestrial shapes. Rather, it turned to the applied approach, so that its study became a pillar in surveying and evaluating land resources and employing their results in preparing development programs for the investment and maintenance of resources from environmental hazards and changes taking place in the landscape as well as building investment plans and managing its resources are in order to achieve the basic goals of the human beings which are safety, prosperity and stability.Geological surveys are a modern style used in applied geomorphology to identify the qualifications to develop plans for any area and also seek to uncover the spatial relationships between man and his environment through his response and challenge to them.The current studies of geomorphology focus on its applied aspects due to the current development in its contemporary techniques such as remote sensing and geographic information systems, which facilitated research procedures and detection of the components of the region easily and with high accuracy and with the lowest costs and effort and in a short time compared to the traditional methods, especially the applied ones.As sophisticated systems are available for creating maps and linking them to various databases of land resources, the importance of studying this area increases, as it is located in areas where dry and semi-arid climates prevail, as it becomes more vulnerable to environmental risks. The study of water erosion (Al-Zubaidi Basin) is important to identify the sensitivity of the surface for the environmental assessment of its reflection on land uses and to build a model for water erosion. For the qualitative evaluation of water erosion, PAP-CAR based on the basin area methodologyThe region is sensitive to geomorphological processes (mofotectonism, morphomimeclimatic and morphodynamics) due to tectonic activation, climatic extremism, dynamic energy and water flow due to the variation in the types of rocks and their characteristics, which led to a variation in their impact on the degree of the predation of the area and its response to the water erosion process and its reflection on land uses.

Water Erosion Risk Assessment in the Kenya Great Rift Valley Region

The Kenya Great Rift Valley (KGRV) region unique landscape comprises of mountainous terrain, large valley-floor lakes, and agricultural lands bordered by extensive Arid and Semi-Arid Lands (ASALs). The East Africa (EA) region has received high amounts of rainfall in the recent past as evidenced by the rising lake levels in the GRV lakes. In Kenya, few studies have quantified soil loss at national scales and erosion rates information on these GRV lakes’ regional basins within the ASALs is lacking. This study used the Revised Universal Soil Loss Equation (RUSLE) model to estimate soil erosion rates between 1990 and 2015 in the Great Rift Valley region of Kenya which is approximately 84.5% ASAL. The mean erosion rates for both periods was estimated to be tolerable (6.26 t ha−1 yr−1 and 7.14 t ha−1 yr−1 in 1990 and 2015 respectively) resulting in total soil loss of 116 Mt yr−1 and 132 Mt yr−1 in 1990 and 2015 respectively. Approximately 83% and 81% of the erosive lands in KGRV fell under the low risk category (<10 t ha−1 yr−1) in 1990 and 2015 respectively while about 10% were classified under the top three conservation priority levels in 2015. Lake Nakuru basin had the highest erosion rate net change (4.19 t ha−1 yr−1) among the GRV lake basins with Lake Bogoria-Baringo recording annual soil loss rates >10 t ha−1 yr−1 in both years. The mountainous central parts of the KGRV with Andosol/Nitisols soils and high rainfall experienced a large change of land uses to croplands thus had highest soil loss net change (4.34 t ha−1 yr−1). In both years, forests recorded the lowest annual soil loss rates (<3.0 t ha−1 yr−1) while most of the ASAL districts presented erosion rates (<8 t ha−1 yr−1). Only 34% of all the protected areas were found to have erosion rates <10 t ha−1 yr−1 highlighting the need for effective anti-erosive measures.

Supplementary Files: Water Erosion Risk Assessment in the Kenya Great Rift Valley Region

Supplementary Files: Water Erosion Risk Assessment in the Kenya Great Rift Valley Region

Evaluation of water washing efficiency and erosion risk in an axial compressor for different water injection conditions

Gas turbines performance losses are mainly due to the deposition of dirt on the compressor blades that needs to be periodically removed. This is the reason motivating the presence of water washing systems (WWS) in most of the compressor gas turbines. Water washing is generally achieved by installing a number of nozzles on the compressor casing and spraying water that clean the dirty surfaces of the compressor. The side effect of such a technique is the rising risk of erosion due to the impact of water droplets on the compressor blades which is even more pronounced when dealing with online water washing systems that is done while the unit is at normal load. The design of these systems must balance benefits and disadvantages associated to the process itself. The benefits can be measured in terms of water washing efficiency that is a quantity not uniquely defined. In previous works, the authors introduced some indices useful to evaluate the spatial cleaning coverage (the wet to the total surface) and the quantity of water mass actually impacting the dirty surfaces (the impacted to injected mass). On the other hand, water washing erosion is a complex phenomenon depending on several parameters, such as the mechanical properties of the blade material, the impact velocity and angle and the droplet diameter. For this reason, the WWS are strongly influenced by the adopted nozzles and by the injection conditions. The present paper aims at assessing water washing for six different injection conditions in the first stage of a real axial compressor. Two-phase CFD simulations are carried out with Ansys Fluent where a User Defined Function implemented by the authors is used to properly model water droplet erosion mechanism and to obtain all the quantities needed to evaluate the washing quality. Results confirm the strong influence of the injection conditions on the main features of the washing system. The study is part of an ongoing partnership between Baker Hughes and Sapienza University of Rome aiming at maximizing the washing of the compressor blades while maintaining the erosion under specific thresholds.

Influence of DEM resolution on the RUSLE model: Case of abandoned quarries in Settat province (Morocco)

Topographic slope information is one of the critical variables, which governs soil erosion. This topographic slope can be derived from the Digital Elevation Model (DEM). Significant discrepancies are found in the estimation of soil erosion using different DEMs of different resolutions. In the present study, the Revised Universal Soil Loss Equation (RUSLE) was used for soils in the Settat province (Morocco) to assess the risk of water erosion caused by abandoned quarries. The soil erosion rate was divided into five classes to illustrate the erosion rate variability using two DEMs (30m and 90m). The impact of topography on erosion was determined by calculating the value of the LS factors. In this case, the values obtained vary between 0 - 120.623 for ASTER DEM (30m) and 0 - 10.225 for DEM SRTM (90m). The results also show that most quarries have a soil loss rate that varies between 0 t/ha/year and 8.1 t/ha/year for ASTER DEM (30 m). However, for DEM SRTM (90 m), the soil loss rate is zero. This suggests that RUSLE model users should use high-resolution input data for a close representation of reality and capture the maximum results with reasonable accuracy.

Dynamic changes in soil erosion risk and its driving mechanism: A case study in the Loess Plateau of China

AbstractThe Loess Plateau has long been considered as a very fragile area that suffers from serious water erosion. With the onset of global climate fluctuations and regional implementation of soil and water conservation measures, it is of great significance to effectively reveal the variations in soil erosion risk and its driving mechanism on the Loess Plateau. Taking the Yanwachuan watershed as a case study and using rainfall, soil, digital elevation model (DEM) and land‐use data, this study applied the Revised Universal Soil loss Equation (RUSLE) model with geographic information system (GIS) technology to analyse the temporal and spatial variations of soil erosion risk and to evaluate the effects of land‐use change and climate change on soil erosion from 1981 to 2016. Future soil erosion risk was also assessed under different land‐use and climate‐change scenarios. Results showed that annual soil loss in the Yanwachuan watershed presented a significant decreasing trend with a rate of 47.928 t km−2 a−1 and that average annual soil loss was 3,543.7 t km−2 from 1981 to 2016. However, some areas, even with good vegetation cover, still had a rather high soil erosion risk (exceeding the severe erosion rate of 5,000 t km−2 in 2000–2016) if located in hilly and gully slope regions. Land‐use change and climate variation contributed 37.2% and 62.8%, respectively, to reducing soil erosion, showing that climate variation played a leading role in current soil‐erosion reduction. In addition, the average soil losses in the 2020s, 2030s and 2040s under different scenarios are predicted to increase by 8.6–42.6% compared with the average soil loss (2,993.8 t km−2) in 2001–2016. Future climate change may be the main driving factor in enhancing the risk of soil erosion. Hence, there is an urgent need to strengthen soil and water conservation research and management in future years.Highlights This study assessed current and future water erosion risk on the Loess Plateau using the RUSLE model. Areas with steep slopes were still experiencing serious soil erosion risk in 2000–2016. Climate change was the main driving factor for soil erosion variation. Future erosion risk is expected to increase under different climate and land‐use scenarios.

Integrating Sentinel-2 Data and PAPCAR Model to Map Water Erosion: Case of Beni Boufrah Watershed

Water erosion causes significant economic losses linked mainly to the silting up of dams and losses in soil productivity, these consequences will increase if soil and water conservation actions associated with development actions are not undertaken. The present work aims to evaluate the water erosion in the basin of the Beni Boufrah located in the Northern part of Morocco. The hierarchy of this basin in plot according to the degrees and the tendencies of the erosion was made using the qualitative PAP/CAR approach (Programme d’Actions Prioritaires/Centre d’Activités Regionales) which is based on the integration of the factors influencing the water erosion, such as the slope, lithology and/or pedology, vegetation cover and land use. This work was conducted in three stages, the first one being predictive based on the analysis of the natural factors influencing water erosion and the processing of databases of developed maps. The second so-called descriptive stage is based on the mapping of different forms and processes of soil loss that occur in the study area. The last step, it allows the integration and the combination of the results of the two previous steps. Its purpose is to provide a precise cartographic product that reflects the reality of the state of soil degradation and the future evolution of erosion. The consolidated erosion map shows that more than half of the basin area (53%) is affected by medium-level erosion, 13% is affected by high erosion level, and 15 % is affected by low-level water erosion. Low-intensity erosion occurs along the river in areas where the slope and lithology favour runoff. The trend map is the final result of the integration phase, it describes erosion trends in the different parts of the basin and is, therefore, a tool to guide decisions on land use planning and tillage methods to limit the risk of water erosion in the basin.
 Keywords: Oued Beni Boufrah, water erosion, PAP/CAR, erosive states, erosion trend.

Assessing temporal trends of soil erosion and sediment redistribution in the Hexi Corridor region using the integrated RUSLE-TLSD model

Accurately evaluating soil water-erosion dynamics and drivers is crucial for mitigating soil and water loss. To simulate the potential or net soil erosion process in China’s Hexi region (a 2.3 × 105 km2 area including three river basins), this study attempted to integrate the transport limited sediment delivery (TLSD) function within the revised universal soil loss equation (RUSLE) model (the spatial resolution of the maps was 90 × 90 m). A geographically weighted regression model was used to evaluate the contribution of influencing factors to the net water-erosion rate and the soil and water conservation benefits of the “Grain to Green Program” (GTGP) (The area proportion of land types in 2015: 6.84% (cultivated land), 3.48% (forest land), 21.68% (grassland), 66.69% (unused land), 0.75% (water), and 0.56% (construction land). The results revealed that the RUSLE-TLSD model could reliably simulate the soil erosion process in Hexi (the Nash-Sutcliffe model efficiency coefficient exceeded 0.602). The potential water erosion rate was between 6.24 and 31.01 t/ha/a from 1982 to 2015, and the net water erosion rate declined slightly, with a slope of −0.0029. Water erosion was severe in high-altitude areas (altitude > 3306 m) with slopes of more than 21° and annual precipitation above 235 mm and weak in low-altitude areas (altitude <1920 m) with slopes less than 4° and annual precipitation below 114 mm. Nearly 10% of the Qilian Mountain National Nature Reserve (QMNNR) areas experienced intensive erosion, and nearly 29% of the QMNNR areas experienced sediment deposition. Slope was the primary factor affecting soil erosion. Extreme precipitation directly aggravated the water-erosion risk, and this factor should be given increased attention particularly in arid and semi-arid regions. The GTGP effectively reduced water soil erosion caused by extreme precipitation and improved water retention and soil consolidation in Hexi.

Using the Methodological Procedures for Water Erosion Risk Areas Identification for Sustainable Land Use

Abstract The countries of the European Union have joined, inter alia, soil protection in the Common Agricultural Policy (hereinafter referred to as CAP). Accelerated soil erosion is a problem resulting from inappropriate land management, which affects both the presence of organic matter and the soil structure. The tool for elimination of negative impacts on soil can be its sustainable use. This requires the use of an accurate system to improve its condition. The first step should be problem identification and localisation. The research is aimed at the identification of water erosion risk areas by using selected methodological procedures. The research area was located at the intensively used hilly land of the Southwestern Slovakia. The digitisation of the manual interpretation of erosion risk areas with the use of aerial photos, erosion modelling, chemical analysis of soil organic matter (SOM) and analysis of soil structure were used. Verification was implemented via the field research with the use of the soil probes. Methods affirmed significant presence of the water erosion in the area. Efficient identification of erosional processes is possible via combination of presented methods by taking into consideration geological, geomorphological, pedological and geographical conditions and the use of the area over a longer period of time. The results of using methods that ensure accurate and effective localisation of erosion surfaces can be used for sustainable land use and its conservation.

LAND CAPABILITY EVALUATION FOR THE EFFECTIVE LAND USE AND SOIL PROTECTION MEASURES IN DOBRICH REGION

An assessment of the suitability of the arable land in the Dobrich region for its effective agricultural use has been prepared using an eight rate classification where the land valuation strategy guarantees the conservation of natural resources, with particular attention to erosion as a limiting factor. Maps of the area with Land Capability evaluation classes for effective agricultural and erosion control land use and the actual risk of water erosion have been developed.This allows the use of an integrated approach to the definition of soil protection measures - taking into account both soil constraints (labeled with subclass land) and the need for prevention against erosion processes. A set of different soil protection practices is recommended, each determined according to the specific soil, topographical and climatic features of the studied area, determined by the class and subclass of the land and depending on the degree of erosion risk and the way of land use (defined by Physical Blocks, 2016). The agronomic assessments according to the soil and climate conditions of the main agricultural crops are lnked to the detailed large-scale database created in the GIS format and the most suitable places for their cultivation on the territory of the Dobrich region have been identified. The agronomic fitness of arable land for the cultivation of wheat, maize, peaches and vines is assessed. Maps for the degree of their agronomic fitness were prepared. It is clear that almost all of the entire territory has a very good and good land for cultivation of these crops.

Spatial distribution of water and wind erosion and their influence on the soil quality at the agropastoral ecotone of North China

Abstract: In semiarid regions, wind and water erosion are serious environmental and ecological problems around world. They have different impacts on soil quality over a range of spatial scales. Analyzing the spatial distribution of soil erosion and understanding the impacts of wind and water erosion on soil quality at the regional scale is vital for mitigating soil erosion risk. In this study we explore the spatial distributions of water and wind erosion around Zhangjiakou city which suffers both water and wind erosion contemporaneously, and detect the influence of soil erosion on soil quality. We find that annual wind erosion intensities range 4.99–10.05 t ha−1 yr−1, and annual water erosion intensities range 2.92–4.14 t ha−1 yr−1. Areas with higher potential wind and total erosion risk occur mainly in northwest and southeast Zhangjiakou city, whereas potential water erosion risk is highest in the southwest and central regions. The highest erosion rates are concentrated in gentle parts of the landscape, where agriculture has led to low vegetation cover. Steeper portions of the landscape, which remain forested, have lower erosion rates. These spatial patterns are dominated by higher wind erosion, which correlates with surface soil coarsening and higher water infiltration, whereas the soil water holding capacity decreases with increasing wind erosion rates. In regions with high water infiltration rates, we find the intensity of water erosion weakened. To mitigate risks of soil degradation, suitable erosion measures should be implemented according to the dominant erosion type, which varies in space.