The Effect of Gabion and Masonry Check Dams on Aggregation of Deposited Sediments in Razin Watershed, Kermanshah, Iran

The purpose of this study was investigating the effect of eleven gabion and five masonry dams on trapping eroded particles in the razin watershed located north of Kermanshah township. The frequency of sand particles increased by 40.67 percent and the percentage of gravel, silt and clay particles decreased by 14.37, 56.55 and 69.93 percent in sediments behind the gabion dams as compared to the watershed soil, respectively. The frequency of gravel particles decreased by 18.89 percent and the percentage of sand, silt and clay particles increased by 5.98, 19 and 23.39 percent in sediments behind the masonry dams as compared to the watershed soil, respectively. Gabion check dams were more useful in trapping sand particles, while the masonry check dams showed more efficiency in trapping silt and clay particles. Gabion and masonry check dams upstream of the watershed had more sand and less silt and clay than the lower dams. Percentage of silt and clay particles increased, unlike the percentage of sand particles, from the beginning of the sedimentation area to the back of the dam. This study showed that in selecting the dam type, it is necessary to investigate the particles size distribution of watershed soil and the combination of the two dam types can be more effective in trapping sediment in the watershed.