برآورد فرسایش خندقی بر پایة معادلات REGEM و اصلاح ضرایب آن‌ در استان اردبیل

نوع مقاله: مقاله پژوهشی

نویسندگان

1 فیزیک و فرسایش اردبیل

2 گروه علوم و مهندسی خاک، دانشکده کشاورزی و منابع طبیعی دانشگاه محقق اردبیلی

چکیده

خندق­های کوچک به دلیل تراکم زیاد در واحد سطح، یکی از مهمترین عوامل تلفات خاک و آب به ویژه در اراضی کشاورزی است. در این پژوهش با انتخاب 81 خندق کوچک در سه حوزه آبخیز از منطقه اُرتاداغ، ملااحمد و سرچم در استان اردبیل، ابعاد خندق­ها با فاصله یک سال تعیین و تغییر طول، عرض متوسط، عمق و حجم آن­ها ثبت گردید. همچنین ابعاد خندق­ها با استفاده از مدل REGEM با فاصله زمانی یک سال برآورد شد و همبستگی بین مقادیر مشاهده شده و برآورد شده بررسی گردید. به منظور اصلاح و بهینه­سازی مدل برای مناطق مورد مطالعه، با استفاده از مدل­های رگرسیونی، روابط مدل اصلاح شد و مجددا برای برآورد ابعاد خندق­ها و تغییرات آن در طول یک سال مورد ارزیابی قرار گرفت. برای اصلاح مدل از پارامترهای تنش برشی بحرانی و عامل فرسایش خاک مدل REGEM برای برآورد ابعاد خندق شامل طول، عرض متوسط و عمق متوسط استفاده شد. نتایج نشان داد مدل REGEM تنها در منطقه سرچم کارایی لازم را در برآورد فرسایش خندقی داشت و میزان ضریب همبستگی برآورد آن با تغییر حجم اندازه­گیری شده خندق­ها برابر با 66/0 به دست آمد. در حالی که برآورد ابعاد خندق­ها با مدل REGEM اصلاح شده، در هر سه منطقه همبستگی معنی­دار با مقادیر اندازه­گیری شده داشت. همبستگی تغییر حجم خندق­ها بین مقادیر اندازه­گیری شده و برآورد شده با مدل اصلاح شده برای اُرتاداغ، ملا احمد و سرچم به ترتیب 76/0، 67/0 و 78/0 تعیین گردید. بنابراین برای کاربرد مدل در مناطق دیگر نیاز به تصحیح مدل متناسب با شرایط منطقه می­باشد.

کلیدواژه‌ها


عنوان مقاله [English]

Estimating of gully erosion based on REGEM model equations and modification of it’s for Ardebil province

نویسنده [English]

  • shokrollah asghari 2
2 Department of soil science and engineering, faculty of agriculture and natural resources, University of Mohaghegh Ardabili
چکیده [English]

Small gully due to high density per unit area is one of the most important causes of soil and water losses in watersheds that have gully erosion. In this research, with the selection of 81 small gullies in three watersheds from Ordadagh, Mulla Ahmad and Sarcham in Ardebil province, the size of gullies was determined with a one-year interval and the change in length, average width, depth and volume of them were recorded. Also, gullies size was estimated using the REGEM model with a one-year interval and the correlation between observed and estimated values was investigated. In order to modify and optimize the model for the studied areas, the model was corrected using regression models and again evaluated for estimating the gullies size and its variations over one year. To correct the model, the regressive shear stress parameters and soil erosion parameters of the REGEM model were used to estimate the dimensions of the gully including length, average width and moderate depth. The results show that the REGEM model only in Sarcham area had the useful efficiency in estimating gully erosion and its estimation correlation coefficient with measured gullies volume changes was 0.66. While estimating the size of the gullies with the modified model, in all three regions, showed a significant correlation with the measured values. The correlation between the measured and estimated values by modified model for gullies volume change was determined to be 0.76, 0.67, and 0.78, for Ordadagh, Mulla Ahmad and Sarcham respectively. Therefore, in order to apply the model in other regions, it is necessary to correct the model according the conditions of the region.

کلیدواژه‌ها [English]

  • Small gullies
  • Modification of REGEM model
  • Estimation of erosion
References

Alonso C.V., Bennett S., and  Stein O.R. 2002. Predicting head cut erosion and migration in concentrated flows. Water Resources Research, 38(12):39-1.

Capra A., Mazzara L. M., Scoicolone B. 2005. Application of the EGEM model to predict ephemeral gully erosion in Sicily, (Italy). Catena,59: 133-146.

Chaplot V. 2013. Impact of terrain attributes, parent material and soil types on gully erosion. Geomorphology, 186:1-11.

Hafezi Moghaddas N. 2011. Engineering Geology. Arses press. 488p. (In Persian)

Jafarai Gorzin B., and Kavian A. 2009. Assessment of Gully Erosion Occurrence in Sorkh-Abad Watershed Using Remote Sensing and Geographical Information System. Iran-Watershed Management Science and Engineering. 3(7): 55-58. (In Persian)

Kemper W.D., and Rosenau R.C. 1986. Aggregate stability and size distribution. In: Klute A. (Ed.). Methods of Soil Analysis. Part 1: Physical and Mineralogical Methods. American Society of Agronomy. Soil Science Society of America, Madison, WI. Pp 425–442.

Kompani-Zare M., Soufi M., Hamzehzarghani H., and Dehghani M. 2011. The effect of some watershed, soil characteristics and morphometric factors on the relationship between the gully volume and length in Fars Province, Iran. Catena, 86:150–159.

Nachtergaele J., and Poesen J. 2002. Spatial and temporal variations in resistance of loess-derived soils to ephemeral gully erosion. European Journal of Soil Science, 53:449– 463.

Nachtergaele J., Poesen J., Steegen A., Takken I., Beuselinck L., Vandekerckhove L., and Govers G. 2001. The value of a physically based model versus an empirical approach in the prediction of ephemeral gully erosion for loess-derived soils. Geomorphology, 40:237–252.

Nayebi H. 2014. Applied Advanced Statistics by SPSS. University of Tehran press. 401p. (in Persian)

Page A. L., Miller R.H., and Keeney D.R. 1982. Methods of Soil Analysis, part2, chemical and microbiological properties. American Society of Agronomy,Inc. Soil Science Society of America. Madison, WI. 510p.

Poesena J., Nachtergaelea J., Verstraetena G., and Valentin C. 2003. Gully erosion and environmental change: importance and research needs. Catena, 50:91– 133

Rafahi H.Gh. 2006. Water erosion and conservation. University of Tehran press. 671p. (In Persian)

Reynolds W.D., Elrick D.E., and Youngs E.G. 2002. Ring or cylinder infiltrometers (vadose zone). In: Dane J.H. and G.C. Topp (Ed.), Methods of soil analysis, Part 4. Physical methods, Soil Science Society of America,Madison, Wisconsin USA. pp. 818- 826.

Rezaei Moghaddam M.H., and Behbodi A. 2011. Application of EGEM in Estimating the Erosion of Ephemeral Gullies in Sarand Chay Drainage Basin. Geographic Space. 35: 135-153. (In Persian)

Shahab H., Emami H., haghnia G.H., Esmali A., and Mahmood Abadi M. 2016. Effect of topography and determination of the most important soil properties on gully erosion development in Ardebil area. Ferdowsi University of Mashshd PhD thesis. 197p (In Persian)

Soleimanpour S.M., Soufi M., Ahmadi H. 2009. Determining Effective Factors on Gully Development in Konartakhte Region, Fars Province. Water and Soil, 23:131-141. (In Persian)

Tekwa I.J., Laflen J.M., MusaKundiri A. 2015. Efficiency test of adapted EGEM model in predicting ephemeral gully erosion around Mubi, Northeast Nigeria. International Soil and Water Conservation Research, 3: 15-27.

Valentin C. J., Poesen J., Yong Li. 2005. Gully erosion: Impacts, factors and control. Catena, 63:132–153.

Wischmeier W.H., and Smith D.D., 1978. Predicting rainfall erosion losses—a guide to conservation planning. USDA Agricultural Handbook, Washington, D.C, 537p

Woodward D.E. 1999. Method to predict cropland ephemeral gully erosion. Catena, 37:393-399.

Zarei H., Najafinejad A., Hosseinalizadeh M., and Alipour K. 2018. Efficiency assessment of the EGEM to estimate gully erosion in Iky-Aghzly watershed of Golestan province. Journal of Water and Soil Conservation, 24(5): 147-162. (In Persian)