Investigation on the Engineering Geology Part of Karkheh from Abdol-Khan to Elhai Village

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.