مدلسازی تغییرات کاربری اراضی و اثرات آن بر سیستم فرسایش در حوضه ی سد علویان با استفاده از تکنیک های سنجش از دور و GIS (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
تصاویر رقومی سنجش از دور از قابلیت بالایی در مدیریت منابع طبیعی برخوردارند که یکی از مهم ترین آنها آشکارسازی تغییرات پوشش و کاربری اراضی است. در حال حاضر با استفاده از تکنیک های پردازش تصویر و مقایسه چندزمانه داده های سنجش از دور می توان تغییرات کاربری اراضی را در طی دوره های زمانی مشخص نموده و با کسب آگاهی از نسبت تغییرات، تغییرات پوشش و کاربری اراضی آتی را پیش بینی نموده و نسبت به مدیریت آنها اقدام نمود. تحقیق حاضر نمونه ای از کاربرد داده های سنجش از دور در آشکارسازی تغییرات کاربری اراضی و مدلسازی اثرات آن در فرسایش است. در این تحقیق از تصاویر ماهواره ای TM ,ETM+ سال های 2015-2002-200-1989 استفاده شده و تغییرات کاربری اراضی در طی سه دوره ارزیابی شده است. پردازش تصاویر ماهواره ای در سه مرحله ی پیش پردازش، پردازش و پس پردازش انجام شد. در ادامه ی طبقه بندی تصاویر ماهواره ای انجام شده و نتایج برای استخراج نقشه های تغییرات و انجام اقدامات لازم به محیط GIS انتقال یافته و با استفاده از تحلیل های مکانی GIS تغییرات کاربری اراضی مورد مدلسازی قرار گرفت. نتایج پژوهش نشان می دهد که در سه دوره یاد شده ضمن افزایش اراضی باغی، تخریب و تبدیل اراضی مرتعی خوب به مراتع ضعیف و اراضی دیم در سطح قابل توجی صورت گرفته است که نقش مهمی در افزایش آسیب پذیری منطقه ی مورد مطالعه در مقابل فرسایش خاک داشته است.Modeling the Trends of the Land Use/Cover Change and Its Impacts on the Erosion System of the Allavian Dam Based on the Remote Sensing and GIS Techniques
Introduction
The modification of the Earth’s terrestrial surface by human activities is commonly known as the land use/land cover change (LULCC) around the globe. Although the modification of the land by humans to obtain livelihoods and other essentials has been a common practice for thousands of years, the extent, intensity, and rate of LULCC are far greater now than they were in the past. These changes are driving forces for local, regional, and global level unprecedented changes in the ecosystems and environmental processes. The empirical studies conducted by researchers from diverse disciplines have found that changes in the land use/land cover is a key to many diverse applications such as agriculture, environment, ecology, forestry, geology, and hydrology.
Satellite Remote Sensing and GIS are the most common methods for the quantification, mapping, and detection of the patterns of the LULCC, because of their accurate geo-referencing procedures, digital formats suitable for computer processing, and repetitive data acquisition. Technically speaking, the remote sensing based digital satellite images have a high capability for natural resources' management operations. Land use/land cover change detection is considered as one of the most important applications in the domain of the remote sensing satellite images. Related to this applicability, it will be possible to apply multi-temporal satellite images for the detection of the land use change. Based on the results obtained from the change detection operation and modeling of the further land use changes, one will be capable to makes better decision for natural resources' management. Based on this statement, the main objective of this research is to represent the applicability of the satellite images for the detection of the land use changes, particularly on the upper areas of the Allavian dam of the Sofi-chai basin.
Dataset and methods
The study area was the upper area of the Allavian Dam in Maragheh. The research was carried out based on the digital interpretations of the Landsat images (ETM+ and TM) of the years 1989, 2000, 2002, and 2015. Based on these images, the land use changes of this region were separately detected for 3 periods. It should be noted that the widely practiced operations such as image preprocessing, classification, and post processing with those related techniques were considered in this study. Indeed, it is widely known that preprocessing before the the change detection phenomenon is very important in order to establish a more direct relationship between the acquired data and the biophysical phenomena. Accordingly, atmospheric and geometric correction were applied as the first step on satellite images. In doing so, the LSLC classes were determined based on the spatial resolution of the satellite images. Then, image enhancement methods were applied to detect each LULC class on the satellite image. Next, GPS based training data was collected in the field operation and integrated with the satellite images. In addition, the supervised maximum likelihood was applied to derive LULC map for each year. The validation step was also part of this section for the accuracy assessment based on kappa coefficient and error matrix.
Results and Conclusion
After developing LULC maps, the results were transformed into GIS environment for the following steps and GIS analysis. The results indicated a significant changes in LULC of the study area. They also indicated that orchards cover had increased throughout the study periods but rich range lands widely converted into poor range lands because of losing the significant canopy of the native plants. Increasing the trend of the orchards area may be in relation with the population growth and this factor can be affected by ( have an effect on) range land degrading. The water supply out of Allavian dam might be another reason for increasing the orchard’s area. The results also acknowledged the capability of the remote sensing for the LULC and change detection analysis. The results of this research are of great importance for decision making authorities in governmental departments such as the ministry of agriculture and natural resources for the purposes of planning and decision making.
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