مقایسه ی روش‌های هیدروگراف واحد SCS و Uniform در برآورد حداکثردبی سیلاب حوضه ی عموقین

نوع مقاله : علمی

نویسنده

دانشیار دانشگاه محقق اردبیلی- دانشکده کشاورزی و منابع طبیعی مغان

چکیده

سیلاب در مطالعات مربوط به بهره‌برداری از منابع آب، ساخت سدها، مدیریت حوضه و مطالعات هیدرولوژیکی اهمیت زیادی دارد. بنابراین، تا حد زیادی دقت این مطالعات و ایمنی تأسیسات آبی بستگی به روش‌های مطاله سیلاب دارد. این مطالعه با هدف مقایسه­ ی روش‌های  هیدروگراف واحد SCS و Uniform  در تعیین بیشینه­ ی دبی سیلاب با استفاده از مدل WMS در حوضه­ ی عموقین واقع در استان اردبیل، انجام شده است. مساحت حوضه­ ی مذکور 78 کیلومتر مربع بوده و برای تعیین مقدار CN منطقه از تلفیق نقشه­ ی کاربری اراضی و گروه هیدرولوژیک خاک (B ,C ,D) به‌دست آمده از تحلیل تصاویر ماهواره لندست 8 در نرم­افزار Idrisi32 به‌دست آمد که برابر 7/78 محاسبه گردید. نتایج واسنجی (RE=7.17، RMSE=0.44) و اعتبار‌سنجی مدل (RE=2.51، RMSE=0.0042 ) با وقایع بارندگی رواناب در منطقه نشان‌داد که میزان حداکثر دبی سیلاب و حجم سیلاب برآورد شده توسط روش SCS به‌خوبی با مقادیر مشاهده­شده مطابقت دارد. همچنین نتایج حداکثر دبی روش‌های SCS وUniform  در دوره­ ی بازگشت‌های 25، 50 و 100 ساله مقایسه شد و نتایج نشان داد میانگین برآوردهای روشUniform  تقریباً 5 درصد بیشتر از روش SCS می‌باشد و بر اساس آزمون T استیودنت، تفاوت بین مقادیرUniform  و SCS در سطح اعتماد یک‌درصد معنی‌دار نگردید. نتایج نشان‌داد در صورتی که زمان تأخیرحوضه با درنظر گرفتن سیلاب واقعی حوضه، محاسبه گردد، روش SCS دقیق‌تر از روشUniform  قادر به شبیه‌سازی سیلاب در منطقه است، با توجه به حساسیت بالای روش SCS به توزیع بارندگی، تحلیل بارندگی در منطقه­ ی مورد مطالعه، برای دستیابی به نتایج مطلوب لازم بوده و توزیع باران و توزیع زمانی آن باید حتی‌الامکان نزدیک به مقادیر واقعی در منطقه باشد.

تازه های تحقیق

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کلیدواژه‌ها


عنوان مقاله [English]

Comparison of Uniform and SCS Unit Hydrograph Methods to Estimate Maximum Flood Discharge of Amughin Basin

نویسنده [English]

  • yaser hoseini
Associate Professor of Moghan College of Agriculture & Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
چکیده [English]

1-Introduction
Flood discharge is of high importance in studies regarding water resource exploitation, flood control, construction of dams, basin management, and hydrologic studies (Alzahrani et al, 2017). Therefore, to a large extent the accuracy of these studies and the safety of water constructions depend on flood study methods. Flood is a natural phenomenon that threatens the life and properties of a large number of people all over the world, and it is impossible to manage water resources in basins without the accurate determination of the peak flood discharge (Badri et al, 2017). The advances in flood estimation techniques have made it possible to use rainfall-runoff models to assess the hydrographic properties of the flood in watersheds and decrease the risks of the flood. Therefore, this study was carried out to compare the SCS unit hydrograph and Uniform methods in determining the peak flood discharge with WMS model in Amughin basin of Ardabil province.
2-Methodology
Amughin basin with an area of approximately 78 km2 is located in the northwest of Iran. The physiographic features were extracted using the basin map (scale: 1:25000) and WMS model. This study applied Arc GIS 9.2 and Idrisi32 software to obtain the properties of the studied basin using DEM (Digital Elevation Map) of the National Cartographic Center, NCC. Remote sensing methodology was utilized to study the

 

 geographical land use changes occurred during the study period. Landsat images of TM and ETM+ of Amughin basin area were collected from the USGS Earth Explorer web site. After image preprocessing, un-supervised and supervised image classification were performed to classify the images into different land use categories. In general, soil hydrologic groups were divided into three subgroups of B, C, and D and CN value of 78.7 was estimated for the Amughin basin based on the geological examination, permeability, vegetation, and hydrologic conditions of the basin soil.
3-Results
The model calibration results showed that the simulated peak discharge and flow volume were in good correspondence with the observed values (RE%= 7.17, RMSE= 0.44). Thus, the calibration results were used for optimum values of parameters. The model was validated using two rainfall events and the model performance indices were acceptable in both cases (RE%= 2.51, RMSE= 0.0042) in SCS method. To evaluate and test model validation, two rainfall events, were used. That the model performance indices were acceptable. Distribution of CN amount in the area showed that the upstream flow had higher CN values and consequently increased flood volume in these areas. Based on the values of obtained CN, the amount of peak flood discharge was calculated for return periods of 25, 50, and 100 years.
4-Discussion and conclusion
According to the results, the SCS model has good agreement with experimental results among the different methods used for estimating flood discharge in the northwest of Iran. In fact, this model requires calibration in the study region. In small watersheds in the northwest of Iran, the SCS model yields better results than the Uniform method because the conditions required for using this model are satisfied in these basins. Moreover, the results obtained from this method can be closer to actual values provided that the watershed concentration time is calculated more accurately. Our results also showed that the SCS model

 
has a high sensitivity to rainfall distribution across the region and that  the rainfall across the region needs to be analyzed to obtain desirable results. Besides, the rainfall distribution and its time distribution should be close to the corresponding values in the region. A comparison between the obtained results of peak discharge from the SCS and Uniform methods in return periods of 25, 50, and 100 years revealed that the average estimates of the Uniform were approximately 5% higher than the SCS method. According to paired T-test, the difference between Uniform and SCS values were not significant at a confidence level of 0.01. Overall, the results obtained from this method can be closer to actual values if the watershed lag time is calculated more accurately using the floods occurred in the studied basin.

کلیدواژه‌ها [English]

  • Rainfall pattern
  • Curve Number
  • Verification
  • Flooding
  • Land use
Al-Zahrani, M., Al-Areeq A., & Hatim, O. Sh. (2017). Estimating urban flooding potential near the outlet of an arid catchment in Saudi Arabia, Geomatics, NaturalHazards and Risk, 8(2), 672-688.
Badri, B., Zarebidaki, R., Honarbakhsh, A., &Atashkhar, F. (2017). Prioritization of Beheshtabad Watershed Sub-Basins for Flood Potential. Natural Geography Research (Geographical Research), 48(1), 143-158. [In Persian]
Dile, Y.T., & Srinivasan, R. (2014). Evaluation of CFSR climate data for hydrologic prediction in data-scarce watersheds: an application in the Blue Nile River Basin. J Am Water Resource Assoc. 50, 1226–1241.
Ghaffariegilandeh, A., Behruz, S., & Ostadibabakandi, E. (2016). Estimation of Curve Number and Runoff Height in Arc-GIS, Case Study, Meshkinshahr City. Hydro geomorphology. 3(9), 159-175. [In Persian]
Hansson, K., Danielson, M., & Ekenberg, L. (2008). A framework for evaluation of flood management strategies. Journal of Environmental Management. 86 (3), 465-480.
Hejazi, A., & Marzbani, M. (2015). Estimation of Maximum Runoff Height and Discharge Using Curve Number Method Case Study: Sarab Darehshahr Watershed. Hydro geomorphology. 2(5), 63-81. [In Persian]
Hoseini, Y., Azari, A., & Pilpayeh, A. (2017). Flood modeling using WMS model for determining peak flood discharge in southwest Iran case study: Simili basin in Khuzestan Province. Applied Water Science, 7, 33-55.
Hosseini, Y. (2011). Comparison of Methods Proposed in WMS Model for Determination of Maximum Flow Discharge in Khuzestan Province and Validation of these Methods. The First Conference on Strategies for Achieving Sustainable Agriculture. [In Persian]
Kowalik, T., & Walega, A.  (2015). Estimation of CN parameter for small agricultural watersheds using asymptotic functions. Water. 7, 939-955.
Moghadasi, N., Karimirad, I., & Sheikh, V. (2017). Assessing the Impact of Land Use Changes and Rangeland and Forest Degradation on Flooding Using Watershed Modeling System. Journal of Rangeland Science, 7(2), 93-106.
Nash, J.E., & Sutcliffe, J.V. (1970). River flow forecasting through conceptual models I: a discussion of principles. Journal of Hydrology, 10, 282–290.
Rauf, M., & Habibi, R. (2015). Estimating Maximum Flood in the Hirchai Basin Using WMS, First National Conference on Architecture and Urban Planning (Thought, Theories and Methods). Malayer, Islamic Azad University of Malayer. [In Persian].
Shaghoian, B., Noroozpour, S., Kiani, M., & Rafiee Nasab, A. (2016). coupled Modclark-curve number rainfall-runon-runoff model. Arabian Journal of Geosciences, 9 (4), 2–13.
Sanyal, J., Denmore, A, L., & carboneau, P.  (2014). Analyzing the effect of land-use/cover changes at sub-catchment levels on downstream flood peaks: A semi-distributed modelling approach with sparse data. Catena, 118, 28-40.
Shannani, H., Sayyede, M., Haidar, Z., & Ramazani, H. (2016). The Effect of Land Use Changes on Flood Hydrographs (Case Study: Abou Abbas Basin). Irrigation Science and Engineering. 40(1), 219-229. [In Persian]
Alizadeh, A. (2011). Principles of Applied Hydrology. Razavi Cultural Foundation Publications, pp. 476-764. [In Persian]
Satheeshkumar, S., Venkateswaran, S., & Kannan, R. (2017). Rainfall–runoff estimation using SCS–CN and GIS approach in the Pappiredipatti watershed of the Vaniyar sub basin, South India, Modeling Earth Systems and Environment. 3 (24), 1–8.
Yousefi Mobarhan, E., Farahmand, K., Fahim, N., & Fahim, E. (2016). Efficiency of Flow-Duration Curves Method for Verification of a Hydrological Model (Case Study: Zola-Chay Watershed), Water and soil Science, 26 (2-1), 101-113. [In Persian].