ABSTRACT
Check dams have been recognized to reduce tributary flood peaks and delay time to flood peaks. However, little has been reported on the quantitative evaluation of check dams in their planned performance. The main objective of this study is to evaluate the effect of check dams on flood peaks and watershed time of concentration. For this purpose, the HEC-HMS rainfall-runoff modeling system was used for obtaining the inflow hydrographs to the main river reach corresponding to different return periods. The hydrographs were then inputted to the MIKE 11 hydrodynamic model that simulated the unsteady flow in the stream and over the check dams. The case study was conducted in the Golabdareh Watershed just north of Tehran, Iran. This study revealed that check dams, representing small scale structural flood control measures, had a relatively insignificant effect on the time of concentration and peak flow of the medium to high return periods, while the flood peaks were considerably reduced in more frequent floods. Moreover, for flood return periods over 5 years, filled check dams were more effective to increase the time of concentration.
