اولویت بندی مناطق منشا سیلاب در حوضه سد درونگر با استفاده از مدل سازی هیدرولوژیکی

سیلاب‌های حاصل از رگیار یکی از مهمترین مخاطرات طبیعی حوضه های آبخیز کشور است که همه ساله خسارات زیادی به بخش‌های مختلف وارد می کند از این رو، برنامه ریزی و مهار سیلاب برای کاهش خطرات احتمالی از اولویت‌های ویژه محسوب می‌شود. از جمله اقداماتی که برای کاهش خطر سیلاب مطرح است، مهار سیل در مناطق منشاء سیلاب است.. هدف اصلی این پژوهش تعیین مناطق منشاء سیلاب در مقیاس زیرحوضه در حوضه آبخیز سد درونگر در استان خراسان رضوی است که با استفاده از مدل modclark در مدل hec-hms انجام شد. برای این منظور ورودی‌های مدل با نرم افزار arcgis استخراج شد و سپس مدل با 6 واقعه رگبار و آبنمود متناظر واسنجی و اعتبارسنجی شد. در مرحله بعد‌، به منظور تعیین مناطق منشاء سیلاب رگیار‌های با دوره بازگشت‌های 10، 25 و 50 سال به مدل وارد شد و با استفاده از شش شاخص سیل‌خیزی، زیرحوضه‌های مختلف اولویت بندی شد. نتایج شبیه‌سازی مدل hec-hms با توجه به مقادیر nse ( 0.797 تا 0.973)، rmse (0.2 تا 0.4) و pbias ( 23.14- تا 13.94 درصد) دلالت بر کارایی مدل در محدوده مطلوب تا بسیار خوب دارد. نتایج اولویت ‌بندی برای دوره بازگشت‌های مختلف نیز متفاوت بود اما در مجموع اختلاف، معنی دار نبود. در دوره بازگشت 25 سال زیرحوضه‌های 53، 9و 56 بیشترین مشارکت در دبی اوج حوضه و در دوره بازگشت 50 سال زیرحوضه‌های 53، 66و 37 بیشترین مشارکت را داشته‌اند. زیرحوضه های 66، 56، 53، 52، 67، 71 و 9 بر اساس هر 6 شاخص مورد بررسی در طبقه بسیار سیل خیز قرار گرفته اند که می‌تواند به عنوان زیرحوضه‌های منتخب در برنامه‌های کنترل سیلاب حوضه مد نظر قرار بگیرد.

prioritization of flood source areas in darongar dam basin using hydrological modeling

introductionfloods caused by rainstorm are one of the most important natural hazards in most watersheds of iran and damage various sectors every year. therefore, planning and flood control can reduce potential hazards. flood control in flood source areas, is one measure to reduce floods and this is usually done most effectively through hydrological modeling. so far, different methods and models have been used to determine flood-prone areas, but the efficiency of these methods in different climatic and environmental conditions is unknown and requires further research. therefore, the purpose of this study is to evaluate the efficiency of modclark model in hec-hms software and determining flood source areas in darungar dam watershed in dargaz city of khorasan razavi province.materials and methodsin this research, spatial distributed hydrological modclark model in the hec-hms was used. for this purpose, rainfall and runoff data of regional stations, digital elevation model (dem) of the watershed, land use map, vegetation, and hydrological soil group maps were obtained from the regional offices.tthe model inputs were extracted with arcgis software and hec-geohms . in this research, gridded curve number method for rainfall loss, modclark method for rainfall-runoff, recession method for base flow and lag method used for flood routing. in the next step, sensitivity analysis, calibration and validation of the model were performed using six rainfall-runoff events. then the design rainfall in the return period of 10, 25 and 50 years were entered into the model. then the contribution of each sub watershed in flood hydrograph in watershed outlet was determined by using unit flood response method and successive single sub watershed elimination. finally priority of each sub watershed in the flood peak discharge and flood volume at the main outlet, were determined.results and discussionthe results of sensitivity analysis for the selected parameters revealed that the parameters related to the curve number (curve number map and cnratio) had the highest sensitivity and the storage coefficient had the lowest sensitivity. then the model was calibrated with sensitive parameters. the mean values of nse, rmse and pbias were 0.90, 0.27 and -3.36% for calibration events and 0.862, 0.35 and -7.71% for validation events, respectively. thus, the efficiency of the model for flood prediction was confirmed. the prioritization results showed that for the return period of 25 years, sub watersheds of 53, 9 and 56 had the highest participation and sub watersheds of 44, 69 and 43 had the lowest participation in the outlet peak flow. in the 50 years return period, sub watersheds of 53, 66 and 37 had the highest participation and sub watersheds of 2, 43 and 44 had the lowest participation in the peak flow. prioritization of sub watersheds based on flood volume criterion, shows more consistent results, so that the first three priorities in different return periods belong the sub watersheds of 53, 66 and 37. despite some differences in prioritization by these two criteria, the spatial distribution of different degrees of flood risk is almost