جستجوی مقالات مرتبط با کلیدواژه "خصوصیات خاک" در نشریات گروه "جغرافیا"

The purpose of this study was to investigate the effect of physical and chemical properties of soil on the creation and spread of gully erosion in the region and by providing appropriate solutions to prevent the spread of this type of erosion in the region. In order to identify the natural features of the basin and collect theoretical issues, the basic topographic maps (scale 1: 25000) of the National Mapping Organization and the geological map (scale 1: 100000) of the Geological Survey of Iran were used. Digital elevation model (DEM) and land use map were extracted from Landsat 8 images in 30 by 30 dimensions. The mentioned maps were prepared in ArcGIS10.5 environment. The mentioned maps were prepared in ArcGIS10.5 environment. Then, with field visits, 15 gully were selected and their location was recorded by GPS, and then soil samples were taken from each gully from a depth of 0-30 cm. In the continuation of the work, 5 points were selected from non-gully areas as areas that were not affected by ditch erosion and their location was recorded and soil samples were taken from a depth of 0-30 cm. Soil samples collected from the basin were examined in the laboratory for physical and chemical properties. Then R software was used for statistical analysis. The results showed that there was no discrepancy between the studied variables in the two groups (A: gully areas, B: non-gullyareas). The results of physical properties showed that the normality of sand data in gully and non-gully areas is confirmed (0.880) and (0.484), respectively. Also, the value of leven test (0.499) expresses the homogeneity of variance between the data of the two groups. Finally, sand was able to show a significant difference between the two areas (0.001).

Gully erosion as one of the common forms of erosion causes deformation of the land surface and its spread is one of the main reasons for the destruction of agricultural lands, communication roads and irrigation system of the basin, especially the plains on the slopes east of the basin to Chaho village. The area is eroded and made inaccessible through the creation and development of ditches and the agricultural productivity of the area is reduced. Therefore, by studing the physical and chemical properties of the soil and also determining the topographic threshold, an attempt has been made to identify the factors affecting gully erosion and to prevent the damages caused by it as much as possible with a more accurate prediction.

The study area is the Shoor River watershed in the East and Northeast of Mohr city, which is located in the south of Fars province with an area of 101350 hectares. This watershed is located between 27 degrees, 27 minutes and 22 seconds to 27 degrees, 49 minutes and 41 seconds North latitude and 52 degrees, 24 minutes and 58 seconds to 52 degrees, 59 minutes and 14 seconds East longitude. According to the divisions of the country's catchments, the study area is part of the catchments of the Shoor and Mehran rivers, which eventually enters the Persian Gulf.In order to initially identify the natural features of the basin and collect theoretical topics, basic topographic maps (scale 1: 25000) of the National Mapping Organization and geological map (scale 1: 100000), Geological Survey and Mineral Exploration Organization were used. ArcMap version 10.3 software was used to draw the maps. Then 15 ditches were randomly selected. To select the topographic threshold, all selected ditches in the relation were used. While to study the physical and chemical properties of soil (sand, clay, silt, PH, EC, TNV, Mg, Ca, K, Ca, SAR, Na) and geometric measurements, gullys based on cluster analysis It was classified in which geometric measurements were considered as dependent variables and soil physical and chemical properties were considered as independent variables. Tests were performed on the data in SPSS software.

The results of clustering analysis showed that the gullys were classified into three groups. Since more than 53% of gullys are in group one, they have been used for statistical analysis. Correlation and multiple regression models were performed to analyze the relationship between dependent and independent variables. The results of Pearson correlation showed that the length and width of gullys had a very strong relationship with the variable of sodium (/ 866) and SAR (/ 826) while it had a negative relationship with the variable of soil PH (-258). Then, using multivariate regression, the relationship between the independent variables and the gully length and gully cross section was determined. The results showed that the amount of sand, SAR, TNV and sodium had the greatest role in the longitudinal and cross-sectional area of the gullys , respectively. However, the presence of OC and K prevents the spread of moat erosion in the region. According to the results of the topographic threshold formula of the region (S=6759.756A^(-.556) ), the surface runoff process was recognized as the dominant hydrological process affecting the spread of gully erosion.

gully erosion plays a major role in soil degradation. Rapid progression of moat erosion at the eastern end of the basin In addition to the destruction of a large area of agricultural land and rangeland of the basin, are a serious threat to several villages, especially the villages of Qala-e-Seyed and Chahoo and even part of the city of Mohr. The results of the longitudinal expansion and cross-sectional area of the gullys show the high impact of SAR, TNV and sodium in the soil in creating and spreading the gully erosion. However, OC and K prevent the formation and spread of gully erosion. the soil texture is mainly sandy and loamy and sand has the highest percentage in all samples. Sand particles weaken the soil structure and in spite of water, they lose their cohesion and the underlying layers dissolve and then the upper surface of the gully collapses and causes the development of the gully. The results of topographic threshold showed that surface runoff causes gully erosion so that the lower the slope of the area, the more upstream area and more runoff is produced and easily washed with aggregates with low stability and creating valleys along the route. It causes gully erosion. Based on the results of the research, it is suggested that due to the high amount of sodium, chemical modification should be done first and then the vegetation in the area should be modified and created. Due to the high production of surface runoff, mechanical runoff can be collected through temporary methods including creating temporary dams, rock dams, and soil dams at the end of gullys. It is suggested that combined methods such as CF statistical methods and ME algorithm for modeling be used to more fully investigate the gully erosion of the area.

The land-use change is one of the critical worldwide issues that has caused a problem in natural resource sustainability. The dynamics of land-use and land-cover change (LULC) affected by the anthropogenic activities and climate change in arid areas, were caused environmental degradation of these areas. This process has the negative effects on soil physicochemical properties. Soil degradation is the key component of land degradation that affected by land-use changes. So that it causes organic waste carbon, decreases the soil aggregate stability and structure and, consequently the raises of soil erodibility. So to understand the impacts related to these changes in land-use (LU), assessment of the effects of these changes on soil characteristics is important. Therefore, the current study aim was to investigate the effect of land-use change on physico-chemical characteristics of soil and erosion in Sistan area.

This research has done in Sistan area. This area laid southeastern border Iran and Afghanistan. The Sistan region forms a part of the Dasht-e-Lut and hence an exhibits extreme arid climatic regime. The region is nearly flat and featureless arid plain with an average height of 465–500m ASL in its eastern parts. In this study, at first spatial land-use changes in Sistan area determined. To achieve this purpose, used satellite images. By using the Landsat satellite images related to the years 2001 and 2019, the land use maps prepared, and by comparison approach in Idrisi Selva software, the map of land-use change was extraction. After that, the areas that converted from rangeland to flood-agri and bare land determined and that accuracy were assessed. Infield operation, 60 soil samples were collected from tow depths 0-25 and 25-50 cm in different land-use such as rangeland, flood-agri, and bare land. The Samples were collected in a completely randomized block design. To study the physical properties of soil, by hydrometer method, by the soil texture, and by measuring the mean weight diameter (MWD), the geometric mean diameter (GMD) and dry stable aggregates (DSA), the aggregate stability was determined. Also, the soil moisture and bulk density were measured. To investigate the chemical characteristics, the soil properties such as organic carbon, acidity (PH), electrical conductivity (EC), sodium absorption ratio (SAR), CaCO3, Na, and available K and P measured in the soil laboratory. The soil erodibility index calculated five characteristics, including sand, silt with fine sand, organic matter, soil structure class, and the infiltration rate class of the soil profile. To analysis the mean of parameters among different land uses were used the Duncan test.

The result of the study of physical properties showed that the percentages of sand, silt, and clay particles among the land-use that under study were significantly different. So that by the land-use change from rangeland to flood-agri and bare land, the distribution of soil particle size differently, that consequently the soil texture has changed from loam-silt-clay class in rangeland to lighter class loam-silt and loam-sand in flood-agri and bare land respectively. According to this change, the aggregate stability of soil inland converted from rangeland to flood-agri, and bare land 34 and 45 percent have decreased. Also by land-use change, the soil moisture 18% and 43 % has decreased respectively. The results also showed that the bulk density of soil, acidity, electrical conductivity, Na, CaCO3 and absorption ratio (SAR), increased in converted land-use whereas, the organic carbon and available K soil, have decreased significantly. In addition, after land-use change, the erodibility index has increased significantly (P < 0.05). So that the amount of this index in flood-agri and bare land compared to the rangeland land-use, more than equal 4 and 7 respectively.    

In this study, for the first time, has investigated the physico-chemistry characteristics of soil and erodibility in land converted from rangeland in Sistan area. The results revealed that the conversion of natural rangeland to flood-agri and bare land had negative effects on the measured soil properties. So that the percent of sand has increased, that changed the distribution of soil particle size, and according to that, the soil texture has changed also. This caused the aggregate stability soil to reduce. In addition, by decreasing the soil moisture, the plant growth has limited in this lands and given the high evaporation potential in Sistan area, the evaporation from land surface increased and according to that the electrical conductivity, acidity, Na and absorption ratio (SAR) in converted lands have increased, whereas, the organic carbon and available K soil, have decreased. This process has caused the Soil degradation, that affected by land-use changing. Therefore, the land-use change by destroying the soil structure and land-cover in converted lands, cause increases the potential of erodibility, that given exist environmental crises in Sistan area, has required the suitable planning to principle productivity of lands in Sistan area.

Re-use of unconventional water (sewage effluent) is one of the plans that can reduce the effects of desertification and it can provide integrated management of water resources in desert. In this direction, it is very important, investigating the effects of urban Wastewater on Soil Properties. The purpose of this research, is Investigating the Effects of sewage effluent of Sabzevar on Soil Properties in the desert areas Barabad of city Sabzevar. To do this, Sampling was done Through Method of Systematic- randomized from the control areas and irrigation areas with wastewater. Results of chemical properties showed, amount of calcium, magnesium, acidity and neutralizing content is without significant change and electrical conductivity, sodium, chlorine and sodium absorption Ratio decreased significantly compared to the control area. Results of Fertility properties showed, significant reduction is in the amount of organic carbon, phosphorus and potassium absorbed in the rstored area compared to the control area. Eventually. Planting plan with wastewater in the studied area showed, In terms of changes in soil properties, There are positive effects and Haloxylon aphyllum Than Atriplix canesences and Nitraria Schoberi evaluated  mre appropriately in terms of improving soil conditions

The arid regions are fragile and sensitive ecological environment and are vulnerable to desertification. This critical area around arid region where desertification occurs determines the ecological stability of the deserts. In order to combat desertification and decreasing its risks, the restoration projects using varieties of plant species were applied that could change the soil properties and soil quality indices. The objectives of this study were to evaluate the effect of Haloxylon planting on soil physical and chemical properties and to determine soil indices in the Ahangaran village, southwestern Roshtkhar city. In view of this, 45 samples were collected from the three control area, between the canopy and under the canopy of Haloxylon aphyllum and soil physical and chemical properties were measured. The results showed that soil pH, lime, electrical conductivity, saturation moisture, clay, sand, carbonate and total nitrogen of the three sampling region were significantly different. The soil quality model were determined using multivariate statistical techniques including factor analysis, redundancy analysis and discrimination analysis and the results showed that pH and lime with highest coefficient are the most important of soil quality under Haloxylon planting in the study area. The soil quality index in the between the canopy and under the canopy of Haloxylon aphyllum is differently significant with control area.

The aim of this study is investigates the effects of different patches shrubs on the soil surface indicators in Gub Gugeh rangelands, in Golestan Province. The sampling was taken along transects of 50 meters, which are 10 meters away from each other. Via LFA models, three factors of stability, infiltration and nutrient cycling using 11 indicators of surface soil in patch and inter-patch were measured. In the study area exist three patches rangelands including shrubs patch Suaeda (Suaeda physophora), sagebrush (Artemisia sieberi) and mixed patches (Artemisia sieberi + Suaeda physophora). The inter-patch areas (barren soils + litter) were identified, as well. The obtained result shows the stable characteristics between mixed patch and sagebrush patch, and there are no significant differences. Considering the permeability index, the highest rate belongs to mixed patch, but, the lowest permeability belongs to the areas of barren soil and litter. The nutrient cycling index indicates significant differences among the patches in the study area. In general, it shows the mixed ecologic patches (Artemisia sieberi and Suaeda physophora) improve the properties of more than other considered patches. Therefore, the mixed patched can be considered as an ecological index in the study area. The studies of functional features of patches of rangelands will help effectively in the detection the healthiness of arid and semi-arid rangelands, the improvement of soil conditions as well as the recognition of the effects of managerial and natural changes of rangelands.

Soil mapping is one of the basic studies in the natural resource sector. The purpose of this study was to analyze spatial of soil properties on the map of arid areas and deserts. For this purpose, a region with an area of 600 hectares in Qom that considered Salt Lake watershed. Specified methods used include inverse distance methods, radial functions, and prediction local general estimate.Kriging and geostatistical methods used include a variety of types Cokriging. The results show the advantages of using geostatistical methods to determine the mapping of soil for methods of defined the maximum is 9.87 and minimum 1.26 and for methods of kriging the maximum is 9.48 and minimum 1.19 and for methods of Cokriging the maximum is 9.64 and minimum is 1.2. In this parameter has the highest correlation with the desired parameter was considered as a covariate. Landsat ETM + data have also been used as a covariate in the interpolation parameters. The results show that the use of satellite data for mapping soil parameters is increased accuracy. Most accurate method was different for each parameter and evaluatedhave different for mapping soil properties.In most of surface parameters the best method was geostatistical methods and in silt parameters the best methods was local estimation method. The best way in most deep parameters was geostatistical methods.

The purpose of the current study is to investigate the effects of some environmental factors on erosion value, to determine the most important governing factors and the relation between erosion of working units and environmental factors (soil characteristics, slope, aspect, elevation, lithology, geomorphology faces and vegetation cover percentage). We used the geomorphology method to prepare a working units map. This map was derived by overlaying slope, aspect, elevation, lithology andgeomorphology face maps.In order to study plant cover, random-systematic sampling in each working unit was conducted in ten plots.Regarding the species type and distribution, the area of each plot was determined based on the minimal area method. Canopy cover of species was determined in each plot. Furthermore, five profiles were sampled within the working units to study soil characteristics at depths of 0-50 cm. Subsequently, the texture, percent of lime, organic matter, gravel, pH and EC were measured. Erosion value was determined in each working unit by the E.P.M. method.Statistical analysis was performed using Principal Components Analysis (PCA) through the PC-ORD4 software program.The results showed that among environmental factors, the vegetation cover, lime percentage, face and organic matter were the first set of factors that determined the change in erosion value by 33.99%.The second set of factors that included loam,stone resistance and clay percentage play contributed to the change by 17.295%. These two sets of factors altogether explain 51.288% of the erosion value variation in VarkeshBasin.