Effectiveness of check dams in sediment control; a survey in kotok watershed in Khuzestan Province, Iran

Abstract

sediment transport are processes that cause annual losses of millions of tons of soil from the natural and agricultural areas in Iran. These processes result in the loss of soil nutrients, as well as filling of reservoirs and deposition of canals, etc. Watershed projects are mainly prepared and executed aiming at controlling soil erosion, flood control, and decreasing their destructive consequences. Evaluation of watershed projects plays a vital role in solving technical issues and investment in this type of projects In this research, we studied the Kotok watershed located in Andika County, Khuzestan Province, Iran. The runoff flowed in this sub-basin pours into the Karun River and then enters into the reservoir of Shahid Abbaspour dam. During the rainfall seasons, the watershed flood causes erosion of the regional lands and delivery of abundant sediment to the reservoir of this dam. Accordingly, corrective structures were built to control the sedimentation, such as dry stone and gabion check dams. Kotok Watershed is divided into 12 working units (parcels); in this study, certain parameters were examined for each parcel including hydrologic group and soil erodibility, parcel areas, the annual amount of sediment, the number and size of the built structures, and the volume of trapped sediment. According to the survey, construction of check dams had significantly controlled the transport of sediment as much as 30% to 80% of annual sediment in those parcels where construction of the structure was possible.