Qualitative and Quantitative Assessment of Check-dams Effectiveness for Flood Sediment Deposition (Case Study: Dam-tang Watershed, Darab)

One of the simple methods for erosion control, flood mitigation and flood damage reduction in the streams is building the check-dams. The present study was carried out to evaluate the performance of check-dams, location across the streams in the retention of the fine sediments in Dam-tang watershed in Darab Iran. For this purpose, two of streams with many stabilized check-dams which were more than 15years old were selected. Deposition of sediments behind the dams, the natural soil and litter along the normal channels 0 -30 cm depth sample preparation was mixed with hydrometer tests and gradation in the tissue. For each stream, three check-dams (one at the far beginning (upstream), the second one at the middle and the third one at the far downstream) were selected. In each stream, a number of samples were taken from retained sediment behind the selected check-dams and also original soil was taken from both sides of the same check-dams. In the same way, results showed that the sand retained behind the first check dam, was more than the sand behind the second and first check-dams, respectively. Therefore, if the retention of the fine sediments is the main purpose of the check dam construction, it is recommended that they be built in the far downstream rather than in the upstream of waterways.