مسعود خیرخواه زرکش
مجید حسینی
محسن محسنی ساروی
محمد روغنی
باقر قرمز چشمه

Assessment of Watershed management practices is one of the main subjects for future planning of natural resources management and restoration projects. Since, there are no tools for assessment of watershed management practices in many basins of the country, and then distributed hydrological models can be used this purpose. The purpose of this study was evaluation of watershed management practices in Kan watershed by HEC-HMS (Hydrologic Modeling System). For this purpose, based on the rainfall-runoff observed events, HEC-HMS model was optimized and calibrated. Next for evaluation, of check dam's effect on time of Concentration (TC), before and after of check dam's construction Tc was calculated and based on field observations, vegetation cover was estimated. These parameters were imported to HEC-HMS for investigation of watershed management practices influences and then flood behavior was simulated. For assessment of watershed management practices, peak discharge and flood volume was calculated for "before and after" condition. Statistical test showed while that the practices had not significant impact on the peak discharge but had a significant effect on flood volume in 95% confidence level. Also for assessment of watershed response to design precipitation, flood hydrographs for 2-100 year return periods were simulated for "before and after" condition. The results showed that with increasing in return period, the effects of structures on peak discharge and flood volume were reduced. On the other word, the most hydrological impact was resulted in lower return periods (2-10year), that flood volume and peak discharge parameters for before watershed management practices, were obtained 0.76 and 0.86 respectively. In another part of research, sediment porosity of check dams in the laboratory and infiltration rate of stream bed based on field measurements, indicated that watershed management practices have the capability to control the flood with ten-year return period. Keywords: Watershed management, Assessment, Infiltration, Flood simulation, HEC-HMS, Kan Watershed