Showing 2 results for Erosion
Volume 18, Issue 47 (4-2007)
Abstract
One of the most important subjects of watershed basins is the protection of soil and water resources with regarding to control of erosion and sediment yield. The empirical methods for estimation of erosion rates and sediment yield measures such as PSIAC and EPM more emphasize environmental factors so mach so that the important lithological agents are not considered. Therefore, in this research attempts are made to propose a suitable and comprehensive method for inherent sensitivity of lithological units. To this end rock units are classified based on mineralogical composition and their textures in 10 orders of erodibility. The order of erodibility of each formation will be hased on average of lithological components. This method is used for microcontinental plate of central Iran to evaluate the model. Based on outcomes of the mentioned classification, more than 83 percents of rock units are classified from moderate- weak to totally loose and sensitive order. In average, the basin is categorized as very sensitive to erosion. With regarding to obtained results in comparison to specific sediment yield rate that obtained from statistical analysis of observed measures, the accuracy and the ability of the method is confirmed.
Volume 18, Issue 53 (7-2003)
Abstract
Karkheh River is the third largest river in the west part of Iran, regarding its high flow. During raining seasons the overflow of Karkheh river destroys villages, bridges, pumping stations and farms in Khozestan plain. In this research by taking samples from water and river banks and beds, and performing different test such as conducting sediment logical and geotechnical test, the capability of marginal erosion and its causes were taken into consideration. Investigations show that the river progresses few meters per year toward the outer – bank. The reasons for this process are as follows. a. Low-grade compaction of the bank sediments. b. Differences between the compaction of the marginal layers. c. Low cohesive of sedimentary layers, which are exposed. d. The presence of disperses minerals in some layers. e. Disregarding the control factors for preventing the marginal erosion. In order to prevent marginal erosion of the river the use of plant cover, construction structures such as retaining wall, rock mesh structure or the construction of artificial cut-off are proposed.
