نوع مقاله : پژوهشی

نویسندگان

• ناصر احمدی ثانی ¹
• کریم سلیمانی ²
• لیدا رزاق نیا ³
• رئوف مصطفی‌زاده ⁴
• جلال زندی ⁵

¹ استادیار دانشکده‌ی کشاورزی و منابع طبیعی واحد مهاباد،دانشگاه آزاد اسلامی مهاباد، مهاباد، ایران

² استاد گروه آبخیزداری، دانشگاه علوم کشاورزی و منابع‌ طبیعی ساری

³ کارشناس ارشد آبخیزداری، دانشکده ی علوم محیطی، مؤسسه آموزش عالی هراز، مازندران، ایران

⁴ استادیار گروه منابع طبیعی، دانشکده کشاورزی و منابع طبیعی، دانشگاه محقق اردبیلی

⁵ مربی گروه آبخیزداری، مؤسسه آموزش عالی هراز، مازندران، ایران.

چکیده

چکیده
با افزایش جمعیت و فعالیت‌های بشری و در نتیجه افزایش تقاضای آب، دسترسی به آب بحرانی ‌شده و ارزیابی و برنامه‌ریزی منابع آب برای استفاده پایدار پیچیده می‌گردد. بررسی قوانین دینامیکی و طولانی مدت رواناب اهمیت و ارزش عملی برای توسعه­ی پایدار و برنامه­ریزی منابع آب دارد. از سوی دیگر در رابطه با رواناب، روش‌های مرسوم اندازه‌گیری آن بسیار پرهزینه، وقت‌گیر و مشکل هستند. هدف از پژوهش حاضر ارزیابی صحت ابزار ArcCN-Runoff برای تهیه­ی نقشه­ی حجم و ارتفاع رواناب در حوضه­ی آبخیز هراز می‌باشد. برای تهیه­ی نقشه­ی کاربری اراضی، تصاویر ماهواره‌لندست سال‌های 1375 و 1390 مورد پردازش و تجزیه و تحلیل قرار گرفت. نقشه­ی گروه‌های هیدرولوژیک خاک تهیه و مـحاسبات بارش سالانه با استفاده از داده‌های روزانه بارش ایستگاه‌های محدوده­ی حوضه برای سال‌های مختلف انجام شد. جهت تهیه­ی نقشه­ی شماره­ی منحنی (CN) و برآورد حجم و ارتفاع رواناب از روش SCS و ابزار ArcCN-Runoff در محیط GIS استفاده شد. سپس رواناب مشاهداتی با استفاده از داده‌های روزانه دبی ایستگاه کره‌سنگ محاسبه و جداسازی جریان پایه انجام گرفت. در نهایت صحت رواناب برآوردی با برآورد درصد خطای نسبی ارزیابی گردید. براساس نتایج خطای نسبی برآورد رواناب در هر دو دوره 1375 و 1390 به‌هم نزدیک و نسبتاً کم (10 درصد) می‌باشد و ابزار به‌کار رفته، رواناب را با صحت حدود 90 درصد در هر دو دوره برآورد کرده است و می‌تواند برای ارزیابی و برآورد رواناب به‌کار برده شود.

تازه های تحقیق

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کلیدواژه‌ها

• کلمات کلیدی: تخمین رواناب
• روش SCS
• کاربری اراضی
• Arc-CN Runoff

20.1001.1.23833254.1397.5.16.8.6

عنوان مقاله [English]

Assessing the Eiciency of Arc-CN Runoff Tool in Runoff Estimation and its Comparison in 1996 and 2011 Years in Haraz Watershed, Mazandaran Province

نویسندگان [English]

• Naser Ahmadi Sani ¹
• Karim Solaimani ²
• Lida Razaghnia ³
• Raoof Mostafazadeh ⁴
• Jalal Zandi ⁵

¹ Assistant Professor, Faculty of Agriculture and Natural Resources, Mahabad Branch, Islamic Azad University

² Professor Department of Watershed Management, Sari Agricultural Sciences and Natural Resources University

³ M.Sc. Graduate of Watershed Management, Faculty of Environmental Science, Haraz Institute of Higher Education

⁴ Assist. Prof., Natural Resources Dept., Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili

⁵ - Lecturer of Watershed Management, Haraz Institute of Higher Education

چکیده [English]

Abstract
Introduction
Due to population growth and human activities and increasing water demand, water availability will be critical and water resource assessment and planning for sustainable use become more complex. The dynamic and long-term laws of runoff are important and have practical value for the sustainable development and planning of water resources. On the other hand, the traditional methods of runoff estimation should be improved regarding the accuracy and spatial variations. The application of GIS extensions is needed to provide water resource assessment data. Therefore, the application of such new techniques has greatly increased in recent years to estimate the runoff characteristics. The SCS method is the most commonly used method for estimating surface runoff, whose accuracy has improved through employing advanced GIS-based tools. The applicability of Arc-CN Runoff tool was tested in different internal and external studies which emphasized the quantitative evaluation of the model results.
Methodology
In this study, the accuracy of runoff estimation by Arc-CN Runoff tool was evaluated based on the land use map in two different time periods (1996-2011). The Landsat satellite images of 1996 and 2011 were processed and analyzed for land use mapping. Map of soil hydrologic groups was prepared in GIS environment using slope and soil texture maps. The annual rainfall calculations were done using rainfall daily data of several years for stations within the basin. The curve number map was used to estimate runoff using SCS method within ArcCN-Runoff tool in GIS environment. The runoff observations of Karehsang Station were calculated using daily flow data and the base flow was separated. Finally, the accuracy of the estimated runoff was assessed by estimating the percent relative error.
Results and Discussion
According to the accuracy assessment of land use maps using the ground-based map, the best overall accuracy and kappa coefficient were respectively 90% and 88%. The results showed that the maximum likelihood algorithm and the combination of main and synthetic bands, classified the land use classes of the study area with an acceptable accuracy. The highest percentage of the area was classified as range and dry farming (62.74%) in 2011. The percentage of rangeland, dense forest, and water zones decreased in 2011 compared with 1996.The map of the hydrological groups shown in this study, consisted of groups B, C and D, respectively covering 15.5, 44.5 and 40% of the study area. The average CN in the years 1996 and 2011 was estimated to be around 79.6 and 81.6.
The average estimated rainfall of the study area using the arithmetic mean, inverse distance weighting, and kriging methods in 1996 were respectively 486.24, 424.4 and 486.1 mm. The estimated annual rainfall values were equal to 521.5 (arithmetic mean), 514.6 (inverse distance weighting) and 521.5 (kriging) mm. Runoff height was the highest in bare lands and residential uses, and the minimum of runoff height values were estimated in good and medium rangelands.
Conclusion
The mean values of total runoff, base flow, and surface runoff have increased in 2011 compared to 1996. The highest CN values in both periods consisted of bare lands and residential area. The runoff height in different land uses and the total runoff height increased in 2011 (11.38 mm) compared to 1996 (8.8 mm), which can be partly due to the degradation and land use change. The results of this study showed that the ArcCN-Runoff tool improved the accuracy of potential runoff estimations, while the relative error of runoff estimation in both periods was relatively low and acceptable. Thus, the implemented tool can be used to assess and estimate runoff height. The results showed that the relative error of runoff estimation in both periods was in agreement and the error amount was relatively low (10%). In addition, the used methods and tools were evaluated with 90% accuracy in both periods and can be used for runoff estimation in data-scarce watersheds.

کلیدواژه‌ها [English]

• Keywords: Runoff Estimation
• SCS
• Land use
• Curve Number
• Arc-CN Runoff