نوع مقاله : مقالات پژوهشی
نویسندگان
1 دانشگاه کردستان
2 دانشگاه اردکان
چکیده
کربن آلی خاک یکی از خصوصیات مهم خاک میباشد که اطلاعات پیرامون تغییرات مکانی آن جهت مدیریت زراعی، تخریب اراضی و مطالعات زیست محیطی حائز اهمیت میباشد. هدف از این پژوهش استفاده از روش شبکه عصبی مصنوعی برای تهیه نقشه کربن آلی خاک میباشد. بنابراین، تعداد 137 نمونه خاک از عمق 30-0 سانتیمتری خاکهای منطقه مریوان استان کردستان برداشت شده و خصوصیت کربن آلی خاک اندازهگیری شد. متغیرهای محیطی که در این پژوهش استفاده شد شامل اجزاء سرزمین و دادههای تصویر +ETM ماهواره لندست میباشد. جهت ارتباط دادن بین کربن آلی خاک و متغیرهای کمکی، از مدل شبکه عصبی مصنوعی بهره گرفته شد. بر اساس نتایج انالیز حساسیت به روش رپر، برای پیشبینی کربن آلی خاک، متغییرهای کمکی شامل شاخص خیسی، شاخص همواری دره، فاکتور LS، شاخص NDVI و باند 3 مهمترین بودند. نتایج این تحقیق نشان داد که مدل شبکه عصبی مصنوعی دارای 80/0، 01/0- و 67/0 به ترتیب برای ضریب تبیین، میانگین خطا و میانگین ریشه مربعات خطا میباشد. لذا پیشنهاد میشود که جهت تهیه نقشه رقومی خاک از مدلهای شبکه عصبی مصنوعی در مطالعات آینده استفاده شود.
کلیدواژهها
عنوان مقاله [English]
Digital Mapping of Soil Organic Carbon (Case Study: Marivan, Kurdistan Province)
نویسندگان [English]
- Sheler Eskandari 1
- kamal nabiollahi 1
- Ruhollah Taghizade-Mehrjardi 2
1 University of Kurdistan
2 University of Ardakan
چکیده [English]
Introduction: Soil organic carbon is one of the most important soil properties which its spatial variability is essential to crop management, land degradation and environmental studies. Investigation of variability of soil organic carbon using traditional methods is expensive and time consuming. Therefore, one of the ways to overcomethis challenge is using digital soil mapping whichcan predict soil characteristics using auxiliary data and data mining methods. Previous studies have shown that digital elevation model (DEM) and remotely sensed data are the most commonly useful ancillary data for soil organic carbon prediction. Artificial neural network (ANN) is a common technique of digital mapping. The region of Marivan in Kurdistan province is one of the forested areas inIran. In recent decades, due to population growth and the increased need for food, thisforested area has been threatened and some parts are now cultivated. Therefore, accurate mapping of soil organic carbon so as to improve land management and prevent land degradation is necessary. The purpose of this research wasusing ANN model and auxiliary data to mapsoil organic carbon.
Materials and Methods: The study area is located in Kurdistan Province, Marivan(cover 20000 ha). Soil moisture and temperature regimes are Xeric and Mesic, respectively. Elevation also varies between 1280 and 1980 m. The main land use typesarecropland, forestland and wetland. The major physiographic units are piedmont plain, mountain and hills with flat to steep slopes. Using stratified random soil sampling method, 137 soil samples (for the depth of 0-30 cm) were collectedand soil organic carbon were measured. In the current study,auxiliary data were terrain attributes and ETM+ data of Landsat 7. Terrain parameters (including 15 factors), bands 1, 2, 3, 4, 5, 6, 7, brightness index (BI) and normalized difference vegetative index (NDVI) were computed and extracted using SAGA and ArcGIS software, respectively. ANN model was applied to establish a relationship between soil organic carbon and auxiliary data. Finally, soil organic carbon weremappedusing ANN and validated based oncross validation method. Three different statistics were used for evaluating the performance of model in predicting soil organic carbon, namely the coefficient of determination (R2), mean error (ME) and root mean square error (RMSE).
Results and Discussion: Based on sensitive analysis of ANN model, auxiliary variables includingwetness index, index of valley bottom flatness (MrVBF), LS factor, NDVI index, and B3were the most important factors for prediction of soil organic carbon. The quantities of R2, ME and RMSE calculated for ANN model were0.80, 0.01 and 0.67, respectively.Soil organic carbon content ranged from0.26 to 8.45 % and the highest contentwasobserved in forestland with hill and mountain physiography and wetland around the lake. It is noteworthy that the differences fordifferent land uses were not statistically significant. Auxiliary data including wetness index, index of valley bottom flatness, LS factor, and B3 in different land uses had statistically significant difference (p
کلیدواژهها [English]
- Digital Elevation Model
- land use
- Satellite image
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