Leila Goli Mokhtari; Najme Hshafiei; Abolalfazl Rahmani
Volume 5, Issue 17 , March 2019, , Pages 1-21
Abstract
Introduction
Soil erosion is a phenomenon that typically occurs in a large part of the earth and the exacerbation of this process, as a limiting factor, can be an obstacle to the management of the land. It reduces the soil fertility and results in the desertification of the fields and the sediment deposited ...
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Introduction
Soil erosion is a phenomenon that typically occurs in a large part of the earth and the exacerbation of this process, as a limiting factor, can be an obstacle to the management of the land. It reduces the soil fertility and results in the desertification of the fields and the sediment deposited in the drains and reservoirs of sediment droplets reduces their intake capacity. Soil contamination is one of the environmental problems that threatens natural resources, agriculture, and the environment. Soil erosion's time and space data plays an important role in management measures, erosion control, and management of catchment areas. Therefore, in order to protect effectively and prevent undesirable effects of erosion, it is necessary to identify the factors involved in erosion to provide an appropriate estimation of the amount of erosion in the area. So far, several methods have been proposed to estimate erosion in areas with different characteristics. The models presented in three categories are empirical, conceptual, and physical models. The empirical models have always been considered for ease of use and availability of the data, and there have been significant advances in their development. The Global Soil Erosion Equation (USLE) is one of the experimental models that has been proposed to predict mortality on grazed lands, but the modified Global Soil Deterioration Equation (RUSLE) has expanded for various uses, including forest, pasture, crop, and bayer lands. Similar to the USLE, the RUSLE model has six factors, but more accurate estimates of rainfall erosion, soil erosion, vegetation, and conservation operations are used to predict soil losses in wider areas and in different conditions such as crops, forests, grassland, and damaged forests. This model estimates soil erosion as a combination of six factors that indicate the rainfall erosivity, soil erodibility, length and gradient, cropping system, and management operations.
Methodology
In this research, the erosion of the Nourabad Mamassani basin using the RUSLE model was studied. The method was descriptive. To prepare the studied basin maps, the topographic map of 1: 50000, the geological map of 1: 100000, Google Earth images, Landsat 8 satellite images, soil layers, monthly and annual precipitation data of synoptic stations were used. In addition, Kriging zoning method was used to prepare the rainfall erosion layer. A regression analysis was used to determine the relationship between the dependent and the independent variables as well as the effect of the most important factor on the annual waste of soil. The annual regression model of the soil was the dependent variable. The rainfall erosivity factors, soil erosion, topography and vegetation were considered as independent variables. As previously mentioned, the model used in this study was the RUSLE global erosion model. It consists of 6 factors as follows
Relationship (1) R.K.L.S.C.P = A
A: soil erosion per unit area. R: rainfall erosion factor. K: soil erodibility factor. L: slope factor. S: slope factor. C: covering agent. P: a protective operation
Results
The annual mean erosion of the soil was determined using the coefficient of erosivity (R), soil erodibility factor (K), topographic factor (LS), vegetation cover factor (C) and conservation factor (P), and the ArcGIS software. The map obtained from this equation is shown in Fig. 7. The erosion values in the studied basin vary from 6 to 75 tons per hectare per year at the pixel level. According to table (3), about 48% of the area is a low erosion class, which mainly includes a large part of the basin. About 28% of the range is in average erosion, and about 23% of the basin is under severe erosion, which is located in the southern part of the basin.
Discussion and Conclusion
Investigating the rainfall erosivity map at the basin level showed that the values of this factor varied from 11 to 31. The erosivity values from the central parts of the basin to the northern part of the trend were decreasing and in the southern parts where rainfall was higher, erosivity has increased. Soil erosion rate varied from 0.25 to 0.48. The results of the vegetation analysis showed that the values of this factor varied from 0.7 to 1.35. The major part of the role of destructive factors on soil erosion was in rain and pasture lands related to the human factors. The study of the soil erosion risk map, which was produced from the combination of erosivity layers, soil erosion, topography, and vegetation, showed that the soil erosion risk level in the basin was variable from 8 to 75 per hectare per year. According to the map of the soil erosion risk, areas with high erosion risk were mainly in uneven areas of the region. Also, the effect of the rainfall erosion on the increase of erosion in the southern parts of the basin had a medium to high erosion risk. Also, areas with a high erosion risk included areas that had a rugged area. The results of this study showed the high capability of GIS and remote sensing to generate the data needed to generate RUSLE factors, resulting in Output data high quality. Therefore, GIS and RS can be effectively used to develop managerial solutions and provide selected choices for managers to solve the erosion problem.
Hossein Negarash; Najmeh Shafiei; Mohammad Sadegh Doraninejad
Volume 3, Issue 6 , January 2017, , Pages 55-73
Abstract
Hossein Negarash[1] Najmeh Shafiei[2] Mohammad Sadegh Doraninejad[3] Abstract Hydro-geomorphology is a branch of physical geography (Physiography) that studies roughness forms caused by water. The study area includes Nurabad plain’s aquifer within its catchment area under catchments of Hendijan ...
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Hossein Negarash[1] Najmeh Shafiei[2] Mohammad Sadegh Doraninejad[3] Abstract Hydro-geomorphology is a branch of physical geography (Physiography) that studies roughness forms caused by water. The study area includes Nurabad plain’s aquifer within its catchment area under catchments of Hendijan Jarahi which are located in Fars province. The study aimed to determine the geomorphologic factors of the plain and their relation to ground water resources and also provide useful maps in order to identify and manage the environment of the aquifer. The method of this research was statistical analysis. Interpolation method was used to study the geomorphology of the area and its relation to ground water resources of the plain and mapping them, and Perarson correlation was used to investigate the relationship between geomorphologic forms with water resources parameters. The results showed that in alluvial fans, and flood plains, the highest correlation with groundwater resources is 99% showing groundwater resources affect the nutrition. The existence of effective feed aquifers are due to permeable sediments. Hydro-geomorphology, of the area is specified through alluvial deposits and alluvial plains of condensation, and water infiltration into the ground in their role. The quality of water resources shows that the electrical conductivity in the southern and central parts (due to the formation of gypsum and marl aquifers) is higher than other parts, and the acidity of the water is 7 which is neutral. Keyword: Hydrogeomorphology, Underground water source, Aquifer, Noorabad Mamasani plain,GIS. [1]- Associate Professor of Faculty of Geography and Environmental Planning, University of Sistan and Baluchestan,Iran [2]- Master student of Hydro Geomorphology, Faculty of Geography and Environmental Planning, University of Sistan and Baluchestan, Iran, Email:shafiei.najmeh2013@gmail.com [3]- Master of Hydrogeology
