Zeinab Sheikhi; Aliakbar Nazari Samani; Haji Karimi; Reza Bayat
Abstract
Gully erosion is a typically threshold process which is important in land degradation and sediment contribution. Having knowledge on driving conditions and affected lands by gullies are crucial for land degradation management. In this research to prepare the gully erosion map over Iran land mass about ...
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Gully erosion is a typically threshold process which is important in land degradation and sediment contribution. Having knowledge on driving conditions and affected lands by gullies are crucial for land degradation management. In this research to prepare the gully erosion map over Iran land mass about scientific references (article, thesis and report) were investigated in order to scrutinizing of spatial data base and gullying map. Location of 2719 gully headcuts under different climate and land use were identified. Environmental attributes including: soil, climate, rainfall and temperature were collected through using of DEM (12.5 and 30 m), and landuse by using of maps, scientific reports, research studies were extracted. The frequency of gullies was investigated in relation to literature investigation. Topographic threshold conditions were determined and the relative frequency of gully area under mentioned environmental factors were analyzed. The results show that the total gully area in Iran is about 1,328,852 ha. The most occurrence of this erosion is in semi-arid climates, with annual rainfall is 250-350 mm, high silt content, low slope (<5%) and under dry farming landuse. The lowest threshold coefficient () in both arid and semi-arid climates is related to ranglands. The coefficient varies from 0.06 to 0.37 in arid climate and from 0.002 to 0.46 in semi-arid climate, which is indicating of mixing process (surface and subsurface) on gully developing. The resistance of sandy soils (due to permeability) and clay soils (due to cohesion) is higher than silty ones The degradation of canopy cover and runoff generating are two main driving forces, which will be more important under climate change in the near future.
Leila Biabani; Hassan Khosravi; Gholamreza Zehtabian; Esmaeil Heydari Alamdarloo; Behzad Raygani
Abstract
Soil erosion modeling is becoming more significant in the development and implementation of soil management and conservation policies. For a better understanding of the geographical distribution of soil erosion, spatial-based models of soil erosion are required. Wind erosion is a significant cause of ...
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Soil erosion modeling is becoming more significant in the development and implementation of soil management and conservation policies. For a better understanding of the geographical distribution of soil erosion, spatial-based models of soil erosion are required. Wind erosion is a significant cause of land degradation and desertification, negatively impacting the economy, society, and environment, particularly in arid and semi-arid regions. To control and reduce the effects of wind erosion, the first step is to identify sensitive areas. The aim of this research is to identify areas susceptible to wind erosion using the ILSWE model in the watershed regions of the Dar Anjir-Saghand Desert, Namak Lake, and Sefidrud. This model has been calculated by combining five erosion indices, including climate erosivity, soil erodibility, surface crust, vegetation cover, and surface roughness. The model's results indicate that climatic factors, such as precipitation, evaporation, and wind, vary across these regions. These factors play a significant role in determining areas that are susceptible to wind erosion. It is noted that other factors, including differences in vegetation cover, soil characteristics, topographic conditions, and the extent of bare lands, salt marshes, sandy dunes, low-density pastures, and rainfed agricultural lands, have also influenced the results of this. In general, this study presents a new method for identifying wind erosion-sensitive areas in various climates. This method can prioritize regions that require further research and corrective measures.
Naser Mashahadi
Abstract
The dynamics of human activities threaten the sustainability of global life-support systems. Analyze of anthropogenic transformation data play a central role in environmental problems evaluation. This study aims to analyze human activities in watershed. Studies and analyzes revealed that the anthropogenic ...
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The dynamics of human activities threaten the sustainability of global life-support systems. Analyze of anthropogenic transformation data play a central role in environmental problems evaluation. This study aims to analyze human activities in watershed. Studies and analyzes revealed that the anthropogenic transformation variables include the type, intensity and trend. Spatial and temporal patterns of the type of activity (land use), intensity and human intervention were studied using satellite images and field observation. The classification and land use map were done in two phases: The functional phase included the main land uses including agriculture, rangeland, urban and water resources, and the activity phase included ten types of land use. The study of the human interventions intensity in land use units was carried out based on the temporal extension of agricultural land development (agricultural land use), the rangeland condition assessment (rangeland land use) and the area extent of under influence (urban area and water resources). The results of land use studies identified that Rangeland lands cover 77.2 percent and agriculture, urban area and water resources land uses accounted for 21.5, 1.1 and 0.2 percent, respectively. The results of the intervention trend indicated that the trend continues from normal conditions to the replacement by technogenous structures. This trend has revealed growth of agricultural activity in rangeland and as well as the tremendous loss in cropland in uneven urban and industrial growth. The results of the study show the compatibility between the three variables of anthropogenic transformation; ie, the type, intensity and trend.
Gholm Reaza Rahi; A Kaviyan; K Soleimani; H Pourghasemi
Abstract
Creating a gully is a reaction to the geomorphologic conditions, this type of erosion extends over a wide range of environments, and the threshold of topography is related to the slope and drainage level and Controls the position and expansion of gullies in different uses. The slop-area equation as a ...
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Creating a gully is a reaction to the geomorphologic conditions, this type of erosion extends over a wide range of environments, and the threshold of topography is related to the slope and drainage level and Controls the position and expansion of gullies in different uses. The slop-area equation as a relationship between the slope and the upstream area of the watershed in any area will in part help predict gully erosion. The above relationship has been influenced by several factors including environmental conditions (climate, lithology, soil type), the type of land use, and the type of effective mechanisms for the creation and expansion of the gully (surface flow, sub-surface flow, dissolation, and piping), and the type of method used for extraction of slope - area is located. And this is the simplest formula used by two parameters to predict gully erosion. The results show that the value of the relationship between -0.233 and -0.205 was obtained. The equation for agricultural use was equal to Y = 5.7426X-0.205and for the pasture use equal to Y = 10.653X-0.233. In this equation, the power can be close but the coefficient of the equation is different. Gully erosion of the whole hinterland (farmland, agriculture) is expanding. The threshold of topography indicates a negative relationship between land area and slop in different kind of agricultural and rangeland. By reducing the slope, more area is needed for the development and expansion of the gully, and most of the gully is due to surface runoff.
Sayyed Alireza Hosseini; Hassan Khosravi; Hamid Gholami; Yahya Esmaeilpour; Artemi Cerda
Abstract
In this study, land use change trend in coastal areas of south of Iran, including Sistan Baluchestan, Hormozgan, Bushehr were studied during 31 years (1988-2019). Landsat satellite images including TM, ETM +, OLI were used for this purpose. The maximum likelihood method was also used to classify satellite ...
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In this study, land use change trend in coastal areas of south of Iran, including Sistan Baluchestan, Hormozgan, Bushehr were studied during 31 years (1988-2019). Landsat satellite images including TM, ETM +, OLI were used for this purpose. The maximum likelihood method was also used to classify satellite images. Vegetation indices (SAVI) and salinity index (SI1) were used to influence land use classes on land degradation and desertification. The results of land use change trend showed that Changes in land use classes of man-made areas and saline lands as the most dynamic land use classes followed an increasing trend of 2.72% and 1.14%, respectively. The results of multivariate regression analysis showed that three vegetation, saline and man-made variables, and four vegetation, saline, man-made and sandy areas explain 22.3% and 37.8% of the dependent variables of vegetation and salinity indices, respectively. Therefore, in more than 60% of changes, other environmental variables are affected. Hence, with respect to the results of land use area and regression analysis and the mean trend of SAVI and SI1 changes, where vegetation and SAVI classes show decreasing trend and saline land and SI1 classes have increasing trend, it can be concluded that land use changes is phenomena that changes ecosystem services with almost irreversible impacts. This will have nothing to do with disturbing the ecosystem balance and intensifying land degradation in coastal areas.
sedigheh mohamadi
Abstract
This research was done to investigate the effects of change in land use on chemical soil properties in Jamalabad region of Baft county of Kerman province. The experiment was conducted in six sites with the same ecological condition as non grazed site (NG) for 10 years, a moderately grazed site ...
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This research was done to investigate the effects of change in land use on chemical soil properties in Jamalabad region of Baft county of Kerman province. The experiment was conducted in six sites with the same ecological condition as non grazed site (NG) for 10 years, a moderately grazed site (MG) and a heavily grazed site (HG), a dry farming site of barley and wheat (D), a long time fallow site for 5 years (F) and a plowed Glycyrrhiza glabra site (Gl T). Soil samples were collected from two soil horizons (0-15 and 15-30 centimeters) based on a randomized complete blocked design with six replications from each horizon in 2013. Samples were sent to laboratory for soil chemical properties as organic carbon, total nitrogen, available phosphorus, available potassium, PH and electrical conductivity. The results indicated that Land use change significantly decreased organic carbon, potassium content, available phosphorous and nitrogen content as 58.2, 21, 23.5 and 71 percent in dry farming site and 58, 17.3, 19 and 60 percent in plowed Glycyrrhiza glabra site compared to non grazed site. A decreasing trend of organic carbon was seen in moderately and heavily grazed sites in comparison to non grazed site as 42 and 56 percent, respectively. Available potassium of moderately and non grazed sites were maximum. Total nitrogen of soil in moderately and heavily grazed sites was decreased in comparison to non grazed site as 0.035 and 0.04 percent. PH of soil was significantly changed only between non grazed and plowed Glycyrrhiza glabra site (Gl T). Electrical conductivity of soil was increased in dry farming site (165 percent) and heavily grazed site (140 percent) in comparison to non grazed site. According to negative effects of land use change on soil quality and remaining this harmful effect after release of dry farming lands, our recommendation to natural resources offices are programs preventing rangeland occupying, minimizing giving off rangelands, rehabilitation of released dry farming by pioneer plants and improvement of soil qualities in root collection designs of Glycyrrhiza glabra.
