تعیین مناسب‌ترین ابعاد سلولی مدل رقومی ارتفاع برای محاسبة عامل توپوگرافی در مدل RUSLE

نوع مقاله: مقاله پژوهشی

نویسندگان

1 استادیار گروه علوم خاک دانشگاه ارومیه

2 دانشجوی دکتری گروه علوم خاک دانشگاه شهرکرد

چکیده

تعیین عامل توپوگرافی (LS) به دلیل پیچیدگی اثر آن بر پیش‌بینی تلفات خاک با مدل RUSLE بسیار دشوار است. هدف این تحقیق تعیین مناسبترین ابعاد سلولی نقشة DEM برای محاسبة عامل LS به روش Moore and Wilson (1992) در منطقهای به مساحت 5326 هکتار در شمال غرب استان تهران بود. بدین منظور، با استفاده از DEM با ابعاد سلولی 10 متر نقشههای DEM با ابعاد سلولی 30 و 50 و 100 و 200 و 400 متر در محیط ArcGIS 9.3 ایجاد شد. سپس، مناسبترین ابعاد سلولی با استفاده از معیار وابستگی مکانی و ضریب تبیین (R2) انتخاب شد. نتایج نشان داد، در تهیة نقشة جریان تجمعی، گودالهای مصنوعی ایجادشده در نقشههای DEM باید رفع شود. همچنین، بررسی تغییرنماها نشان داد عامل LS به‌دست‌آمده از نقشة DEM با ابعاد سلولی 50 متر دارای بیشترین وابستگی مکانی (613/0) و ضریب تبیین (983/0) است. بنابراین، DEM با ابعاد سلولی 50 متر منجر به تولید نقشة عامل LS دقیقتر شد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

A Determination of the most Suitable Cell Size of the Digital Elevation Model to compute the Topographic Factor in RUSLE

نویسندگان [English]

  • FARROKH ASADZADEH 1
  • SALMAN MIRZAEE 2
  • MAHBOOBEH TAYEBI 2
1 Assistant Professor, Dept. of Soil Science, Urmia University
2 Ph.D Student, Dept. of Soil Science, Shahrekord University
چکیده [English]

Preparation of the topographic factor (LS) map in RUSLE model is a very tedious step because of the complicated effects of topography on soil loss. The objective of this study was to determine the suitable cell size of Digital Elevation Model (DEM) for computing LS factor by the method of Moore and Wilson (1992) in a 5326 ha area, northwest of Tehran Province. Towards this end, cell sizes of 30, 50, 100, 200 and 400 m were derived from the 10 m cell size in ArcGIS 9.3. The appropriate cell size was selected making use of the criteria of spatial dependence and the coefficient of determination (R2). Results revealed that in the preparation of flow accumulation map, the sinks created in digital elevation models must be resolved. Also, analysis of variograms showed that the calculated LS factor obtained from DEM of 50 m cell size is of the most spatial dependence (0.613) with the highest coefficient of determination (R2=0.983). As a result, a DEM of 50 m cell size was found out to lead to the production of a more accurate LS factor map.

کلیدواژه‌ها [English]

  • DEM
  • Soil erosion
  • LS factor
  • Geostatistics
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