Evaluation of the effects of constructed rehabilitation dams on maximum and volume of watershed discharge

In this study, the hydrological processes of Khaveh Watershed located in Markazi province, Iran were simulated and the effect of check dams on floods in this basin was evaluated. To assess the impact of watershed management structures on floods, flood volume and peak discharge with different return periods were calculated. In order to estimate the irrigation rate of Khaveh Watershed, in this study, the method of Justin was studied. Then, flooding situation of Khaveh Watershed was simulated using HEC-HMS model. For this purpose, the flood hydrographs resulting from the design storms with different return periods in the pre- and post-construction states of watershed management structures were compared with each other. The results showed that the constructed dams clearly reduced the peak discharge and flood volume of the region. Based on the results, the construction of corrective structures has reduced the peak flow, increased the base time of the hydrograph and increased the time to the peak of the hydrograph in different return periods. For the 5, 10, 20, 50, and 100-year return periods, the peak is 0.6 to 3.3, 4.9 to 2.7, 9.4 to 1.5, and 6, hours respectively. Discharge decreased to 0.8 and 22.4 to 12.4 cubic meters per second. Also, the base time of the hydrograph for the mentioned return periods increased from 6.8 to 11.2, 9.3 to 0.16, 2/10 to 17.5, 5/10 hours to 18.5 and 10.10 to 29.3 hours. The latency in time-to-peak for hydrographs due to the construction of structures was approximately 3.5 h.