عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Contribution of subwatersheds in outlet flood properties is one of the essential activities in flood management projects. Application of hydrologic models for simulation of rainfall-runoff process is necessary owing to lack of hydrometric stations in all outlets of subwatersheds. In this study the HEC-HMS model version 2.2.2 applied in order to determine flood characteristics in subwatershed outlets leading to investigate watersheds contribution in peak flood and volume at a reach in Jaghargh watershed in Khorasan Razavi province. To achieve the study purpose 5 rainfall-runoff events, were used for calibration and validation of model after collecting necessary rainfall and runoff data from exciting stations. Vegetation cover, soil and land use maps were also combined in Arc view 3.3 software to get CN (Curve Number) map. The flood hydrographs resulted from rainfall events with return periods of 10, 20 and 50 years were then derived. The effect of each subwatershed on peak flood and volume was also simulated single successive subwatershed elimination technique. The results showed that 66.16% of peak flood reduction (39.42 m3/s) and 65.98% flood volume reduction (298.01 m3) for peak flood with 20 years return period belong 4 subwatersheds located in up and midstream of Jaghargh watershed while one of the subwatershed at the vicinity of outlet got the first priority in flood production and contribution per unit area. The result of the study is helpful for drawing proper policies in flood management with critical subwatersheds management in the study area.