Assessment of Watershed Management Projects on Flood Hydrograph using HEC-HMS Model (Case Study: Goosh-Bahreh Watershed)

Quantifying the effects of watershed management projects is a first step in the evaluation of their efficiency. Selecting suitable index for evaluation is an important concern in an evaluation process and is determined on the basis of project type, evaluation method, required accuracy, and available data. Watershed management projects have been initiated in Goosh-Bahreh Watershed, Khorasan Razavi province, since 1993. Considering the importance of watershed management projects evaluation, peak flood discharge and flow volume were adopted as suitable indices. Field surveys and available recorded documents were used to provide required data and information on locations and specifications of the projects which are built on the main streams. To quantify the effects of the projects, river flow was simulated by using HEC-HMS model. The results showed that biological and mechanical projects lead to a decrease of 36.21% and 34.78% in peak discharge and flood volume at different return periods, respectively and the effect of watershed management projects on the peak discharge and flood volume decreases as return period increases. This research showed positive effects of watershed management projects on flood discharge and flood volume in the Goosh-Bahreh Watershed.