Mojtaba Soleimani-sardo; Esmaeil Silakhori
Abstract
Today, land use change is considered as a challenge of environmental issues and known as an ecological problem. Land use changing is one of the most important parameters in planning over time. The purpose of this study is to detect land use changes in the Jiroft Basin in the years 1997, 2008, and 2018 ...
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Today, land use change is considered as a challenge of environmental issues and known as an ecological problem. Land use changing is one of the most important parameters in planning over time. The purpose of this study is to detect land use changes in the Jiroft Basin in the years 1997, 2008, and 2018 and it’s predicting in 2040. For this, Landsat images were collected and the preprocessing steps, including atmospheric and radiometric corrections, were done by ENVI software. A false-color combination, as well as an NDVI vegetation index map, were prepared for these years. Land use maps were prepared by supervised classification using maximum likelihood algorithm. The land use changes evaluated by Land Change Modeler (LCM) in these periods. Finally, land use map for 2040 was predicted by the Markov chain and IDRISI software. According to the Kappa index, the exported maps showed an acceptable accuracy (>0.76). Land use changes between 2008 and 2018 showed that the urban areas, agricultural lands, gardens, salty lands, and barren area were increased, but rangelands and forests were decreased. In the coming years, it is expected that with the current management method, the urban areas, agriculture and barren area will increase, while forest, gardens, and rangeland areas will decrease. To reduce the land use change effects, it is recommended to act according to sustainable development by notice to the ecological potential of the land.
Abdulvahed Khaledi Darvishan; Jalal Faraji; Leila Gholami; Mohsen Khorsand
Abstract
The dynamics of rainfal erosivity (R), crop management (C) and soil erodibility (K) factors compared to the others (topography-LS and land management-P) is the most important note for the correct estimate of soil erosion at different time bases. Spatio-temporal estimates of soil erosion in the representative ...
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The dynamics of rainfal erosivity (R), crop management (C) and soil erodibility (K) factors compared to the others (topography-LS and land management-P) is the most important note for the correct estimate of soil erosion at different time bases. Spatio-temporal estimates of soil erosion in the representative paired watersheds are of particular importance due to their educational functions as well as the possibility of generalizing the results to larger areas of the country. Therefore, in the present study, while examining the dynamics of R, C and K factors in the Khamsan representative paired watershed, the distribution map of soil erosion in seasonal and annual time scales were prepared using RUSLE model for two water years of 2015-2016 and 2017-2018. The results showed that soil erosion in winter with values of 3.94 and 4.95 t ha-1 y-1 accounted for about 49 and 74% of the total erosion of the year, respectively. Considering the melting conditions in calculating the K factor for the winter along with the lack of vegetation in this season led to a higher estimate of soil erosion than other seasons. These results are in consistent with plots soil loss data recorded in different seasons and the higher concentration of suspended sediments in the rivers especially in March. In the water year of 2015-2016, the distribution of rainfalls in the autumn was much higher than in the spring, so that soil erosion in the autumn accounted for about 33% of the total erosion of the year. In the water year of 2017-2018, although the average annual soil erosion was less, but due to more distribution of erosive rainfalls in winter at the same time with the lack of vegetation on the soil surface and the soil melting, the rate of winter erosion was very high.
Ali Jafari; Davood Nikkami; Esmail Abbasi; Fateme Tavakoli Rad
Abstract
Improper land use management has inverse impacts on available resources. To reduce these environmental and economic effects of soil erosion, there is a need for proper watershed plans. Land use optimization is of the solutions for achieving sustainable development and reducing the loose of resources. ...
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Improper land use management has inverse impacts on available resources. To reduce these environmental and economic effects of soil erosion, there is a need for proper watershed plans. Land use optimization is of the solutions for achieving sustainable development and reducing the loose of resources. The main objective of this research was determining the optimal level of land use to increase the income of residents and reducing the effect of erosion in the Sana Dam Watershed. To apply an optimal pattern of land used for minimizing soil erosion and maximizing land income by a multi-objective programming model, optimal scenarios were chosen proportion to the shape of objective functions and constraints. For this purpose a linear programming model was used for three different scenarios of a) present land use conditions b) present land use condition with some applied land use management and c) standard land use conditions according to principles and scientific criteria. The results showed that present land use is not in optimal level and should be changed. Also, results demonstrated that the amount of soil erosion could be decreased by 5.3, 31.7 and 43.4 percent and the amount of net income could be increased by 47.73, 242.57 and 242.57 percent by land use optimization in present land use conditions, present land use condition with some applied land use management and standard land use conditions, respectively.
Davood Nikkami; Hadi Chamheydar; Mohammad Hossein Mahdian; Ebrahim Pazira
Abstract
Environmental and economic impacts of soil erosion are due to improper land management in a watershed. Although it is impossible to stop soil erosion completely under natural conditions, there is a great need to control erosion for proper land use planning. According to the scarcity of literature in ...
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Environmental and economic impacts of soil erosion are due to improper land management in a watershed. Although it is impossible to stop soil erosion completely under natural conditions, there is a great need to control erosion for proper land use planning. According to the scarcity of literature in the area of soil nutrient evaluation with optimization models, the main objective of this research is determining the optimum level of land uses to minimize soil erosion and nutrients losses and maximize people incomes that live in a watershed. For this purpose, Abolabbas Watershed in the north-eastern part of Khouzestan Province was chosen for this research. A linear programming model was used in three different scenarios including current land use condition without land management, current land use condition with land management and standardized land use condition. Results demonstrated that the current land uses are not optimized for the least soil erosion and nutrient losses and high income. At optimized conditions, the area of forests and orchards increased by 1.81 and 55.7% respectively, rangelands with no changes, and irrigated and drylands decreased by 67.5 and 31.4% respectively. Also, results showed that land use optimization, in current land uses with no land management, decreases total soil erosion by 3.2% and total nutrient soil losses by 2.5 and increases total income by 29.7%, in current land uses with land management, decreases total soil erosion by 35.3% and total nutrient soil losses by 70.2 and increases total income by 37.2%, and in standardized land uses, total soil erosion by 47.2% and total nutrient soil losses by 70.4 and increases total income by 41.8%. Sensitivity analysis, also, showed that the change in the area of orchards and Irrigated lands has the most effects on increasing income and decreasing soil erosion and nutrients losses in Abolabbas watershed.
Reza Bayat; Bagher Ghermez Cheshmeh; Hoseingholi Refahi
Abstract
The rate of soil erosion and sediment yield depends on different factors. Vegetation cover is more variable factor effecting occurrence of soil erosion in comparison to the other factors in a given watershed. The main purpose of this study was to investigate the role of canopy cover resulting from land ...
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The rate of soil erosion and sediment yield depends on different factors. Vegetation cover is more variable factor effecting occurrence of soil erosion in comparison to the other factors in a given watershed. The main purpose of this study was to investigate the role of canopy cover resulting from land management on sediment yield. Taleghan watershed was selected as a study area due to the availability of sufficient data. Necessary information was provided for MPSIAC model and was made in GIS environment and all needed calculations were done for preparing sediment yield map. The result of the comparison of the calculated and the estimated sediment yield indicated similarity of them (i.e. 98.3% similarity). For impact assessment of vegetation cover effect on sediment control, canopy cover was changed in a range of ±5 to 25% percent with 5% interval in both good and bad conditions. The effect of these changes was applied to bare soil percentage as well. The related thematic maps were prepared and sediment yield was determined. The result showed that sediment yield varied because of changing canopy cover. The increase and decrease of canopy cover by 25%, affected the sediment yield to change by -29.6% and 26.8% respectively.
Ravanbakhsh Raisian; Amir Hossein Charkhabi; Mohammad Nekoueimehr
Abstract
One of the main factors accelerating soil erosion in the watersheds in Iran is improper management including overgrazing and improper land use changes of pastures into agriculture. This problem is true in the whole Karoon watershed. Therefore, the objective was to study the effects of land use changes ...
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One of the main factors accelerating soil erosion in the watersheds in Iran is improper management including overgrazing and improper land use changes of pastures into agriculture. This problem is true in the whole Karoon watershed. Therefore, the objective was to study the effects of land use changes on soil loss in Gorgak sub-watershed. The statistical design was split plot design with pasture and rain fed agriculture as main factors. A drop maker rainfall simulator with 40 mm/hr intensity and 30-minute rainfall period was used on five field locationsunder two soil moisture conditions of air-dry and field capacity and three slope classes of 10-20, 20-30, and 30-40%. A total of 180 sediment and runoff measurements were made using the above rainfall simulator under field conditions for two land use systems of rain fed cereal and overgrazed pastures. All the measurements were done in triplicates (5 fields x 2 land uses×2 moisture content×3 slope classes×3 replicates = 180 plots). The results showed the soil loss under overgrazed and air-dry soil condition was 45.6 times more than the rain fed agricultureunder the similar soil moisture condition. However, the results showed the soil loss under overgrazed and field capacity soil moisture condition was 2.33 times more than the rain fed agriculture under similar soil moisture condition. Once the soil loss was compared for different slope classes of 10-20, 20-30, and 30-40 slope percent, the results indicated the soil loss under overgrazed and air-dry soil condition were 4.77, 5.19, and 2.34 times more than the rain fed agriculture under similar soil moisture condition. Overall, soil loss under overgrazed conditionwas 3.38 times more than rain fed agriculture. Therefore, although most soil conservationists generally believe that the rain fed agriculture in Iran is very improper managed and it has high soil erosion rates but the results of this study showed the overgrazed pastures in the north Karoon watershed need much more priority for any soil loss measures and controls.
