Determine Soil Loss Research Articles

The value of precipitation intensity factor (R-factor) in determining soil loss (based on the example of the Akkanburlyk river basin)

Currently, it is important to calculate the soil flushing, optimize it and organize preventive measures. Soil leaching is one of the most intense trends, which has a significant negative impact on land resources and the national economy. Soil erosion is divided into two parts depending on the main formation: wind erosion and water erosion. One of the main factors influencing the formation of water erosion is intense and abundant precipitation. Calculation of precipitation intensity (coefficient R) using the interpolation method in the presented work. GIS technologies were used for this purpose and, accordingly, algorithms were considered. The Akkanbulik River basin is 131 km long from east to west and 99 km wide from north to south. There are low mountains to the east of the basin, and to the west, due to its location on the plain, precipitation decreases as you move from east to West. As a result, the average value in the eastern region is 639 mm, and in the western region -572 mm. Fine-grained soils are more prone to soil erosion, for example, in areas with high rainfall and winds. Intensive erosion processes lead to a decrease in soil fertility, deterioration of the quality of sown seeds and pastures. All this causes huge damage to agriculture. This article is devoted to this issue and uses the interpolation method in GIS technology to determine the intensity of precipitation (factor R). The results of the study showed that in the agricultural lands of the Akkanburlyk river basin, the maximum R-factor values corresponded to the eastern part of the basin 280-290, and the minimum values corresponded to the western part of the basin in the range of values 253-260.

Monitoring soil erosion in support of achieving SDGs: A special focus on rainfall variation and farming systems vulnerability

The Sustainable Development Goals (SDGs) and soil-related activities are closely intertwined. Healthy soil ecosystems promote the survival of life on Earth and uplift agricultural productivity. One of the issues that is putting healthy soil ecosystems at risk is soil erosion. The Central Highlands of Sri Lanka were chosen because it is a humid, tropical nation that is particularly susceptible to climate threats. Soil erosion was tracked and predicted in connection to rainfall variation in order to reduce soil erosion in farming systems and in supporting the achievement of the SDGs. A revised universal soil loss equation (RUSLE) was executed to determine soil loss. Rainfall variance was calculated using trend analyses of extreme rainfall indices and rainfall erosivity. Soil erosions for the year 2040 under the Representative Concentration Pathways (RCP) 2.6 and 8.5 scenarios were predicted using a variety of machine learning techniques, including artificial neural networks (ANN), support vector machines (SVM), and adaptive network-based fuzzy inference system (ANFIS). Results indicated a positive trend in rainfall erosivity and several other extreme indices. In addition, soil erosion rates increased, with October recording the highest monthly erosion rates. Based on 2020 soil erosion rates, soil erosion model forecasts suggest that erosion may range from 4 % to 22 % in 2040. Under the RCP 2.6 and 8.5 climate scenarios, the rate of soil erosion can be raised from 10.5 t/ha/yr to 12.4 t/ha/yr, respectively. These facts indicate that rainfall-induced soil erosion will increase the vulnerability of the Central Highlands and pose a severe danger to the achievement of the SDGs. In order to ensure the well-beingof the soil ecosystem, this research offered strategies to monitor and anticipate soil erosion in support of achieving the SDGs to protect the healthy soil ecosystem. This methodology can be replicated to minimize soil erosion in farming systems elsewhere.

Determining The Soil Loss Susceptibility To Forest Fires By Using RUSLE And A New Approach In Çınarpınar Forestry Enterprise, Turkey

Soil erosion by water (WSE) is an environmental, economic, and sociological problem in the world. Nowadays, forest fires have triggered more WSE, especially in the Mediterranean basin. Therefore, the present study aims to determine the effect of forest fires on soil loss susceptibility in the Çınarpınar Forestry Enterprise, Turkey. The RUSLE model was used to determine soil loss. Two soil loss maps were generated for the actual situation (base scenario) and forest fire scenario. For the forest fire scenario, R, K, and LS factors in the RUSLE model were modified based on the forest fire severity index. Finally, two maps representing base and forest fire scenarios were compared. The actual mean soil loss was found as 5.34 t ha-1 year-1 in the Çınarpınar Forestry Enterprise while the mean soil loss was determined as 12.44 t ha-1 year-1 for the forest fire scenario. It was found that forest fires would increase soil loss by more than 2 times in the study area. Areas with very low soil loss susceptibility to forest fires constitute 41.97% of productive forests, while areas with very high, high, medium, and low soil loss susceptibility constitute 3.64%, 9.28%, 27.50%, and 17.61% of productive forests, respectively. It was also revealed that there is not always a linear relationship between fire severity and soil loss susceptibility under natural conditions. Consequently, it is hoped that this study will help decision-makers in the implementation of the multi-purpose approach, which aims to reduce the risk of both forest fire and soil loss.

Analysis of mathematical models to estimate erosivity

The main cause of soil degradation in humid tropical and subtropical environments is water erosion, characterized by being the most important in Brazil. The main factors that determine soil losses by water erosion are erosivity, erodibility, topography, soil use and management and conservationist practices. Proper conservation planning requires knowledge of the factors that influence local erosion. The quantification of soil losses due to water erosion helps to define management techniques and conservation practices appropriate for each province. The municipality of Rio Largo - AL, is located in the metropolitan region of Maceió, within the physiographic region of the Coastal Tablelands. The objective of this work was to determine the erosivity of rainfall for the municipality of Rio Largo - AL, through rainfall data from 1963 to 2015. These data were tabulated to calculate rainfall, coefficient and its relationship with erosivity using six equations. The average annual rainfall calculated was 1800 mm for the observation period of 52 years, showing a wide variation in rainfall distribution, with the rainy season concentrated in the months of April to August. The computed average annual erosivity index was 3761 MJ mm ha-1 h-1 year-1, ranging from 312 to 7211 MJ mm ha-1 h-1 year-1. The months of May, June and July correspond to the most critical period in relation to the erosive potential of the rains and the months of October, November and December are the least critical.

Assessment of soil erosion using the GIS-based erosion potential method in the Kebir Rhumel Watershed, Northeast Algeria

Soil erosion is an important factor that should be considered when planning renewable natural resource projects, effects of which can be measured by modelling techniques. Therefore, disintegration models determine soil loss intensity and support soil conservation practices. This study estimates soil loss rates by water erosion using the Erosion Potential Method (EPM) in the Kebir Rhumel Watershed located in Northeast Algeria. The area is north to south sub-humid to semi-arid, receives irregular rainfall, and has steep slopes and low vegetation cover which makes it very vulnerable to erosion. The main factors in the EPM (soil erodibility, soil protection, slope, temperature, and rainfall) were evaluated using the Geographical Information System (GIS) and data provided by remote sensing technologies. The erosion intensity coefficient Z was 0.60, which indicates medium erosion intensity. While the results showed the average annual soil erosion of 17.92 Mg∙ha–1∙y–1, maximum and minimum losses are 190.50 Mg∙ha–1∙y–1 and 0.21 Mg∙ha–1∙y–1, respectively. The EPM model shows satisfactory results compared to some studies done in the basin, where the obtained results can be used for more appropriate management of land and water resources, sustainable planning, and environmental protection.

A field technology for soil erosion research: Conceptual analysis and preliminary results

Soil erosion is a ubiquitous geomorphologic process that critically affects land degradation rates and ecosystem sustainability. Yet we still don’t have a proper field technology to observe it under field-scale experiments let alone having the data for the verification and calibration of soil erosion models. A desirable soil erosion field technology needs to meet at least the following requirements: (1) it does not restrict natural field runoff; (2) it can be conveniently applied to a field-scale experiment with or without vegetation; (3) it is sensitive for short-term soil erosion observations; (4) it provides information on the sediments and (5) it can quantify soil loss and in-field sedimentation budget. There is a mesh-marker method that meets most of the above mentioned requirements except it does not determine soil loss, a major limitation to its application. This study was initiated to develop a soil erosion field technology that can meet the five criteria mentioned. Reported here is the conceptual analysis of the methodology and the preliminary results of the experiments. Other than meeting the above five criteria, the technology can determine soil erosion parameters such as the sediment delivery ratio.

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.

Geomorphic Control on Soil Erosion – a Case Study in the Subarnarekha Basin, India

<p>Geomorphology depicts the qualitative and quantitative characteristics of both terrain and landscape features combined with the processes responsible for its evolution. Soil erosion by water involves processes, which removes soil particles and organic matter from the upper sheet of the soil surface, and then transports the eroded material to distant location under the action of water. Very few studies have been conducted on the nature and dynamics of soil erosion in the different geomorphologic features. In the present investigation, an attempt has been made to assess the control of geomorphologic features on the soil loss. Universal Soil Loss Equation (USLE) was used to determine soil loss from the various geomorphological landforms. Principal component analysis (PCA) was implemented on the USLE parameters to determine the degree of association between the individual principal components and the USLE-derived soil loss. Results obtained from the investigation signify the influence of the various landforms on soil erosion. PC5 is found to be significantly correlated with the USLE-derived soil loss. The results ascertained significant association between the soil loss and geomorphological landforms, and therefore, suitable strategies can be implemented to alleviate soil loss in the individual landforms.</p>

New Insight on Soil Loss Estimation in the Northwestern Region of the Zagros Fold and Thrust Belt

Soil loss is one of the most important causes of land degradation. It is an inevitable environmental and socio-economic problem that exists in many physiographic regions of the world, which, besides other impacts, has a direct bearing on agricultural productivity. A reliable estimate of soil loss is critical for designing and implementing any mitigation measures. We applied the widely used Revised Universal Soil Loss Equation (RUSLE) in the Khabur River Basin (KhRB) within the NW part of the Zagros Fold and Thrust Belt (ZFTB). The areas such as the NW Zagros range, characterized by rugged topography, steep slope, high rainfall, and sparse vegetation, are most susceptible to soil erosion. We used the Digital Elevation Model (DEM) of the Shuttle Radar Topography Mission (SRTM), Tropical Rainfall Measuring Mission (TRMM), Harmonized World Soil Database (HWSD), and Landsat imagery to estimate annual soil loss using the RUSLE model. In addition, we estimated sediment yield (SY) at sub-basin scale, in the KhRB where a number of dams are planned, and where basic studies on soil erosion are lacking. Estimation of SY will be useful in mitigation of excessive sedimentation affecting dam performance and watershed management in this region. We determined the average annual soil loss and the SY in the KhRB to be 11.16 t.ha−1.y−1 and 57.79 t.ha−1.y−1, respectively. The rainfall and runoff erosivity (R factor), slope length (L factor), and slope steepness (S factor), are the three main factors controlling soil loss in the region. This is the first study to determine soil loss at the sub-basin scale along with identifying suitable locations for check dams to trap the sediment before it enters downstream reservoirs. The study provides valuable input data for design of the dams to prevent excessive siltation. This study also aims at offering a new approach in relating potential soil erosion to the actual erosion and hypsometric integrals.

Sugarecane molasse and vinasse added as microbial growth substrates increase calcium carbonate content, surface stability and resistance against wind erosion of desert soils

Wind erosion is one of the main factors of soil degradation and air pollution in arid and semi-arid regions. In this study we evaluated microbial-induced carbonate precipitation (MICP) as an alternative soil conservation method against wind erosion using sugar cane molasse and vinasse as growth substrates in comparison to tryptic soy broth (TSB). The three substrates were applied in laboratory tests with and without addition of MICP cementing solution (1 M urea plus calcium chloride) to two sandy soils differing in calcium carbonate content. The performance of MICP solution inoculated with a cultured urease-producing strain of Sporosarcina pasteurii was compared to that of an autoclaved MICP solution. For control we also performed a blank treatment without substrate, MICP solution and inoculation. In addition to lab tests in which we determined the effects of treatments on soil pH, electrical conductivity (EC), calcium carbonate (CaCO3) content and surface penetration resistance, we performed wind tunnel experiments to determine soil loss by deflation under different wind velocities. Applying vinasse and molasse strongly increased soil CaCO3 content and penetration resistance, with and without addition of inoculated or non-inoculated MICP solution. Vinasse generally had stronger effects than molasse, while TSB was less effective, especially on penetration resistance. The addition of MICP solution in most treatments did not enhance but rather decrease the substrate effects. In the treatments with vinasse and molasse, increase in penetration resistance translated into substantially decreased soil loss in the wind tunnel tests, down to around one third of the loss in the blank treatment. In contrast, soil loss substantially increased in the treatments with TSB, probably due to the high input of sodium with this substrate. Our results show that molasse and, even more, vinasse can have a strong soil stabilization effect against wind erosion, which is primarily related to the formation of CaCO3 content and does not depend on additional amendments. Thus, these substrates have a great potential to be used on their own as environmentally friendly and cost-effective amendments to control wind erosion of bare sandy soils in arid environments.

Spatial and temporal variability of soil loss in gully erosion in upper Blue Nile basin, Ethiopia

Gully erosion has many negative impacts on both cultivated and grazing lands in Ethiopian highlands. The present study was conducted in Chentale watershed, Ethiopia, to quantify the contribution of gully erosion, and to assess its temporal changes. Within the Chentale watershed, we selected a sub-watershed (104.6 ha) and nested gully catchment, and gauged for stream flow and sediment concentration data in 2015 and 2016. We measured gully dimensions before and after the onset of the rainy season in 2016 to determine soil loss due to gully erosion. The temporal changes of gully expansion were determined by digitizing gully plain area from Google earth images taken in 2005 and 2013. The results support that gullies were expanding at higher rate in recent years. Area covered by gullies in the watershed increased from 1.84 to 3.43 ha between 2005 and 2013, indicating that the proportion of the watershed covered by gullies was nearly doubled in the investigated period. The estimated soil loss from the main watershed and gullies catchment was 6 and 2 t ha−1 year−1 in 2015, and was 7 and 9 t ha−1 year−1 in 2016, respectively. The results support that gullies were the main contributors of soil erosion in the watershed, and that integrated soil and water conservation measures are required to reduce soil erosion.

Filling the European blank spot—Swiss soil erodibility assessment with topsoil samples

AbstractSoil erodibility, commonly expressed as the K‐factor in USLE‐type erosion models, is a crucial parameter for determining soil loss rates. However, a national soil erodibility map based on measured soil properties did so far not exist for Switzerland. As an EU non‐member state, Switzerland was not included in previous soil mapping programs such as the Land Use/Cover Area frame Survey (LUCAS). However, in 2015 Switzerland joined the LUCAS soil sampling program and extended the topsoil sampling to mountainous regions higher 1500 m asl for the first time in Europe. Based on this soil property dataset we developed a K‐factor map for Switzerland to close the gap in soil erodibility mapping in Central Europe. The K‐factor calculation is based on a nomograph that relates soil erodibility to data of soil texture, organic matter content, soil structure, and permeability. We used 160 Swiss LUCAS topsoil samples below 1500 m asl and added in an additional campaign 39 samples above 1500 m asl. In order to allow for a smooth interpolation in context of the neighboring regions, additional 1638 LUCAS samples of adjacent countries were considered. Point calculations of K‐factors were spatially interpolated by Cubist Regression and Multilevel B‐Splines. Environmental features (vegetation index, reflectance data, terrain, and location features) that explain the spatial distribution of soil erodibility were included as covariates. The Cubist Regression approach performed well with an RMSE of 0.0048 t ha h ha−1 MJ−1 mm−1. Mean soil erodibility for Switzerland was calculated as 0.0327 t ha h ha−1 MJ−1 mm−1 with a standard deviation of 0.0044 t ha h ha−1 MJ−1 mm−1. The incorporation of stone cover reduces soil erodibility by 8.2%. The proposed Swiss erodibility map based on measured soil data including mountain soils was compared to an extrapolated map without measured soil data, the latter overestimating erodibility in mountain regions (by 6.3%) and underestimating in valleys (by 2.5%). The K‐factor map is of high relevance not only for the soil erosion risk of Switzerland with a particular emphasis on the mountainous regions but also has an intrinsic value of its own for specific land use decisions, soil and land suitability and soil protection.

EVALUATING WATER EROSION RISKS IN SOME WADIS OF NORTHWESTERN COAST ZONE – EGYPT

Field experiments were conducted in 2015 – 2016 winter season, at wadi El- Raml area. Wadi El – Raml is located southwest, Mersa Matruh city, Egypt. Slope of the experimental site is about 5 percent in south – north direction. The treatments were as follows: Bare soil, traditional cultivation without soil conditioners, cultivation with Ceramic conditioner at rate of 20, 40, and 80 t.fed-1, cultivation with bokashi conditioner at rate of 20, 40, and 80 t.fed-1 and coal ash conditioner at rate of 20, 40, and 80 t.fed-1. The total number of treatments was 11. Each treatment was replicated 3 times. The soil conditioners was added on the soil surface after carrying out tillage operation and then mixed with the soil surface layer. Thirty-three bounded plots having edges of soil with approximately 20 cm height were used to determine soil loss associated with runoff. Each plot was 21 m length and 2 m width. At the down slope end, Gerlash trough were placed, 0.5 m long and 0.2 m wide, closed at the sides and covered with movable lid. An outlet pipe extended from the base of the gutter to the collection containers present below the soil surface. Rainfall amounts, duration, and intensity were measured for every rainstorm with an automatic rain gauge at the site of experiment. The amount of soil loss and runoff water for every rainstorm was determined by maintaining the containers undisturbed for a sufficient time, so that, the solid constituents in the runoff water could precipitate. The precipitated solids were collected and measured gravimetrically after drying at 105°C overnight. Soils of wadi El Raml are mainly sandy loam in texture with deep soil profile. The climatic conditions of the area is defined as arid Mediterranean type, it is characterized by short rainy seasons during October to March. About 75 percent of the total annual rainfall as recorded from November to February. The remaining period of the year is characterized by long dry season (6-7months), except for few rainy storms in April, May and September. The average annual rainfall is 175.4mm. the effective storms were sex storms the runoff coefficient of 3% seams reassemble. However, the lowest runoff yield was obtained when adding Bokashi conditioner with rate of 80 t.fed-1 under all storms,). It is clear that runoff values associated with bare soil were higher than those for the soil treated by non-traditional soil conditioners. From another point, Ceramic conditioner added on the soil surface with the rate of 20, 40 and 80t.fed-1 led to reduce runoff by 37, 49 and 56.5%, respectively, as compared with cultivated soil . With respect to adding bokashi as soil conditioner on the soil surface with the rate 20, 40 and 80 t.fed-1, runoff values under all storms was reduced to 45.2, 59.6 and 67.7%, respectively, The influence of the applied traditional cultivation and applied some soil conditioners on the amount of soil loss under natural rainfall. The highest rates of soil losses resulted from bare soil treatment 1.23 ton/fed. Year this rate lies within the permissible limits of soil loss by erosion, which range from 1 to 5 tams per acre per yeas, With respect to planting without soil conditioners, it is clear that such practice reduced the amount of soil loss by 24.2% relative to that for bare soil treatment, This behavior could be attributed to the fact that plants protect a portion of the soil surface from the energy of rainfall impact, thereby, soil detachment decreased. Growing plants also create obstructions to eater flow over land, slowing down runoff velocity and consequently its carrying capacity and thus, reducing soil loss.

The role of soil surface properties on the particle size and carbon selectivity of interrill erosion in agricultural landscapes

The selective nature of interrill erosion – the preferential mobilization and transport of soil particles – can lead to the enrichment of fine-grained soil particles (<63μm) and organic carbon (OC) within the mobilized soil. This study investigated the effects of slope gradient, vegetative cover, soil moisture content, texture and organic matter content, as well as their interactions on soil loss, particle size distribution and organic carbon content of soil mobilized under simulated rainfall within two contrasting agricultural regions in Canada. Overall, it was found that the eroded material was enriched in both fine-grained and carbon-rich particles relative to the source soil. It was demonstrated that dispersing and sieving both the source soil and the mobilized soil to <63μm (i.e., removal of sand and large particulate organic matter) reduced the relative enrichment of both fine-grained soil particles and OC, which would allow for a more direct comparison of physical and biogeochemical properties between the source and mobilized soil. Furthermore, it was demonstrated that while the soil loss and the degree of enrichment were negatively correlated, there were differences in which soil surface properties had a significant effect in determining soil loss and the selectivity of both fine-grained and organic-rich soil particles and how these surface properties interacted. This suggests that while soil loss may be a good predictor of the degree of enrichment, the factors that control these two processes are different, which is important in understanding the process of selectivity. It was also shown that the OC content of both the source and mobilized soil was positively correlated to the degree of soil aggregation in addition to the silt and clay content.

Effects of soil management techniques on soil water erosion in apricot orchards

Soil erosion is extreme in Mediterranean orchards due to management impact, high rainfall intensities, steep slopes and erodible parent material. Vall d'Albaida is a traditional fruit production area which, due to the Mediterranean climate and marly soils, produces sweet fruits. However, these highly productive soils are left bare under the prevailing land management and marly soils are vulnerable to soil water erosion when left bare. In this paper we study the impact of different agricultural land management strategies on soil properties (bulk density, soil organic matter, soil moisture), soil water erosion and runoff, by means of simulated rainfall experiments and soil analyses. Three representative land managements (tillage/herbicide/covered with vegetation) were selected, where 20 paired plots (60 plots) were established to determine soil losses and runoff. The simulated rainfall was carried out at 55mmh−1 in the summer of 2013 (<8% soil moisture) for one hour on 0.25m2 circular plots. The results showed that vegetation cover, soil moisture and organic matter were significantly higher in covered plots than in tilled and herbicide treated plots. However, runoff coefficient, total runoff, sediment yield and soil erosion were significantly higher in herbicide treated plots compared to the others. Runoff sediment concentration was significantly higher in tilled plots. The lowest values were identified in covered plots. Overall, tillage, but especially herbicide treatment, decreased vegetation cover, soil moisture, soil organic matter, and increased bulk density, runoff coefficient, total runoff, sediment yield and soil erosion. Soil erosion was extremely high in herbicide plots with 0.91Mgha−1h−1 of soil lost; in the tilled fields erosion rates were lower with 0.51Mgha−1h−1. Covered soil showed an erosion rate of 0.02Mgha−1h−1. These results showed that agricultural management influenced water and sediment dynamics and that tillage and herbicide treatment should be avoided.

Exposed roots as indicators of geomorphic processes: A case-study from Polylepis mountain woodlands of Central Argentina

Soil erosion is a serious problem of land degradation in many parts of the world, and particularly in mountain rangelands. To understand this process it is necessary to develop methods to assess soil erosion rate in a quick, economic and accurate manner. Based on the analysis of exposed Polylepis australis roots, we tested a dendrogeomorphological method for determining soil loss rate in rills and gullies. Few studies considered non-coniferous tree rings in soil erosion analysis and we used, for the first time, an experimental procedure of root exposure and provided a comparison with roots exposed by gully erosion. Our main results showed that as a consequence of soil erosion, exposed roots changed from root-like to a more stem-like wood anatomical structure. The percentage of vessel area per tree-ring area decreases by an average of 22% to 43% during the first and second year after exposure, respectively. Moreover, and during the same time interval, the mean vessel area decreased 32% and 65%, and the number of vessels increased 7% and 48%, respectively. Scars formed at the upper side of the exposed roots are coincident with changes in wood anatomy, and both evidences may be applied to reconstruct an erosion process. This study confirms that the wood anatomy analysis of partially exposed roots can be used to determine the year in which roots are exposed and provides a useful tool to monitor soil erosion rates with a high accuracy.

Geographic Variation of USLE/RUSLE Erosivity and Erodibility Factors

There is a great reliance on the Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE) to predict long-term rainfall erosion in relation to land management in both the United States and the rest of the world. In the USLE/RUSLE modeling approach, geographic variations in soil loss associated with climate and soil are taken into account through variations in the rainfall-runoff erosivity factor (R) and the soil erodibility factor (K) and equations developed in the United States to predict the values for these factors are often used outside the United States without validation in the area that they are applied. Data on rainfall kinetic energy required to calculate the event erosivity index, EI30, are seldom directly available and consequently, EI30 values are often calculated using rainfall intensity-kinetic energy relationships that may produce erroneous results because the rainforming systems at a location differ to a great extent from those occurring at the location where the drop-size data were obtained. Also, failure to consider runoff as an independent factor in producing rainfall erosion in the USLE/RUSLE leads to spatial variations in K that cannot be determined simply from measured soil properties. Erosivity indices that include runoff as a factor may lead to soil erodibility factors that are better related to measured soil properties but that potential has yet be realized. Meanwhile, models like RUSLE2 take account of the runoff effect on soil loss through temporal variations in K that are empirically related to rainfall and temperature in the United States but the method is untested elsewhere. The modeling approaches adopted USLE/RUSLE and RUSLE2 are extremely useful in determining soil loss for land management purposes despite any real or perceived lack of ability to predict event soil loss accurately.

Use of the Universal Soil-Loss Equation to determine water erosion with the semi-circular bund water-harvesting technique in the Syrian Steppe

This research was conducted through the rain season 2009 -2010, in Mehasseh Research Center at (Al Qaryatein), The area is characterized by a hot and dry climate in summer and cold in winter with an annual average rainfall of 114 mm. Three slopes (8%, 6%, 4%) were used in semicircular bunds water -harvesting techniques with bunds parallel to the contours lines at flow distance of 18, 12 and 6 m. The bunds were planted with Atriplex Halimus seedlings. Graded metal rulers were planted inside the bunds to determine soil loss and sedimentation associated with the surface runoff, and metallic tanks were placed at the end of the flow paths to determine agricultural soil loss from water runoff. A rain intensity gauge was placed near the experiment site to determine the rainfall intensity that produced runoff. The treatments were done in three replications. The amount of soil erosion (in tons per hectare per year) increased with increasing of the slope, the highest recorded value was 38.66 at slope of 8% and the lowest 0.05 at 4% slope. The amount of soil erosion also increased with increasing of water run distance, which was 38.66 T.ha-1.yr-1 at 18 m and 0.05 T.ha-1.yr-1 at 6 m . Bunds with different diameter of water harvesting reduced soil erosion by about 65% at slope of 8%, 55% at 6%, and 46% at 4%. The input parameters of Universal soil-loss equation were found to be suitable for determining soil erosion in this arid and semi-arid region. DOI: http://dx.doi.org/10.3126/ije.v3i2.10499 International Journal of the Environment Vol.3(2) 2014: 1-11

Modeling post-fire water erosion mitigation strategies

Abstract. Severe wildfires are often followed by significant increase in runoff and erosion, due to vegetation damage and changes in physical and chemical soil properties. Peak flows and sediment yields can increase up to two orders of magnitude, becoming dangerous for human lives and the ecosystem, especially in the wildland–urban interface. Watershed post-fire rehabilitation measures are usually used to mitigate the effects of fire on runoff and erosion, by protecting soil from splash and shear stress detachment and enhancing its infiltration capacity. Modeling post-fire erosion and erosion mitigation strategies can be useful in selecting the effectiveness of a rehabilitation method. In this paper a distributed model based on the Revised Universal Soil Loss Equation (RUSLE), properly parameterized for a Mediterranean basin located in Sardinia, is used to determine soil losses for six different scenarios describing both natural and post-fire basin condition, the last also accounting for the single and combined effect of different erosion mitigation measures. Fire effect on vegetation and soil properties have been mimed by changing soil drainage capacity and organic matter content, and RUSLE factors related to soil cover and protection measures. Model results, validated using measured data on erosion rates from the literature and in situ field campaigns, show the effect of the analyzed rehabilitation treatments in reducing the amount of soil losses with the peculiar characteristics of the spatial distribution of such changes. In particular, the mulching treatment substantially decreases erosion both in its mean value (−75%) and in the spatially distribution of the erosion levels over the burned area . On the contrary, the breaking up of the hydrophobic layer decreases post-fire mean soil losses of about the 14%, although it strongly influences the spatial distribution of the erosion levels.

ERODIBILIDADE DO SOLO NOS TABULEIROS COSTEIROS

In order to determine soil losses caused by water erosion, in different situations, erosion prediction models, such as the Universal Soil Loss Equation (USLE), are used. Their application on agricultural and environmental planning depends on the determination of the USLE factors, including erodibility (K factor). The objective of this study was to determine erodibility for the main soil classes of the Brazilian Coastal Plains region, in Aracruz, Espirito Santo State. The experiment was established in the following soils: medium/clayey texture Yellow Argisol (PA1), Haplic Plinthosol (FX), and moderately rocky Yellow Argisol (PA2). For the calculation of soil erodibility, data of erosivity and soil losses, from November 1997 to May 2004, were used. Soil losses samplings were performed for each rainfall event regarded as erosive. The erodibility values were 0.007 Mg h MJ -1 mm -1 ; 0.017 Mg h MJ -1 mm -1 ; and 0.0004 Mg h MJ -1 mm -1 , for PA1, FX, and PA2, respectively.