hamzeh saeediyan; Hamidreza Moradi
Abstract
By determining the threshold of runoff and erosion by rain simulator, it can be determined rainfall amount that causes runoff in different conditions with more speed and accuracy and lower cost. After determining the threshold of runoff and erosion in each region, using biological methods and operations ...
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By determining the threshold of runoff and erosion by rain simulator, it can be determined rainfall amount that causes runoff in different conditions with more speed and accuracy and lower cost. After determining the threshold of runoff and erosion in each region, using biological methods and operations can prevent the conversion of runoff to flood. In this research, considering that the threshold of runoff and erosion occurs simultaneously and mistakenly only the term of runoff threshold is used in different researches and do care less about erosion threshold and in order to determine the most important factors affecting the simultaneous threshold of runoff and erosion of different land uses of Aghajari and Gachsaran formations, part of Margha and Kuhe Gach watersheds of Izeh city with an area of 1609 and 1202 Hectare selected. This study was conducted to determine the relationship between runoff and erosion threshold using a rain simulator with some soil physical and chemical properties such as very fine sand percentage, sand, clay, silt, pH, electrical conductance, moisture, calcium carbonate and organic matter in different land uses of Aghajari and Gachsaran formations. Then, sampling was done at 13 points and with three replicates in Aghajari and Gachsaran formations at different rainfall intensities of 0.75, 1, and 1.25 mm/min in 3 land uses of rangeland, residential area, and agricultural land using a rain simulator. SPSS and EXCEL soft wares were used for statistical analysis. The most important factors affecting runoff and erosion threshold were identified by multivariate regression. In general, in Gachsaran formation in all three land uses, clay and calcium carbonate showed the highest role in increasing the threshold of runoff and erosion. The most roles in reducing runoff and erosion threshold showed very fine sand and moisture content in Gachsaran Formation. However, in the Aghajari Formation, in all three land uses, the highest role in increasing the threshold of runoff and erosion, showed clay and organic matter. In addition, the most roles in reducing the threshold of runoff and erosion in the Aghajari formation showed very fine sand and soil sand and salinity.
Shahla Tavangar; Hamidreza Moradi; Alireza Massah Bavani; Mahmood Azari
Abstract
Climate is a complex system that changing mostly due to increased greenhouse gases and global warming, leading to intensification of change in climatic factors such as precipitation amount and intensity of extreme precipitation events. In effect of climate change in the future, change amount and volume ...
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Climate is a complex system that changing mostly due to increased greenhouse gases and global warming, leading to intensification of change in climatic factors such as precipitation amount and intensity of extreme precipitation events. In effect of climate change in the future, change amount and volume of the soil erosion is expected which the most important sensitive factor will be the rain fall erosivity. The aim of this study was to determine the effect of climate change on rainfall erosivity factor. For this purpose the HadCM3 model from A1B scenario was used and downscaling with LARS-WG model was used. So monitoring of rainfall erosivity factor for three periods of 2011-2030, 2045-2065, and 2080-2099 in north of Iran was simulated. Results show that rainfall erosivity factor in Sangdeh, Babol, Korkorsar, Anzali, Behshar and Gorgan stations will be increasing during the 2011-2030 period but for stations in Babolsar, Hashtpar, Rasht and Gorgan in the period 2045-2065 and 2080-2099 decreased. According of calculations, maximum changes of the rainfall erosivity factor in future will be occurring during the 2011-2030 and it’s minimum will be occurring period the 2080-2099. So largest rainfall erosivity factor was simulated about 42.6 MJ mm ha-1 h-1 for Hashtpar station during the 2011 to 2030 period. The obtained results show that the erosivity factor increase will be during the current century in the north of Iran.
