تأثیر توسعه اراضی شهری بر الگوی سیمای سرزمین و ریسک اکولوژیکی (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
در سال های اخیر زمین های کشاورزی آسیب جدی دیده که باعث تخریب سیمای سرزمین شده است. هدف از این پژوهش این است که آسیب های به وجود آمده در چهار شهر ارومیه، میاندوآب، نقده و مهاباد مورد بررسی قرار گرفته شود. این تحقیق از لحاظ روش شناسی توصیفی تحلیلی و از لحاظ هدف کاربردی است. برای بررسی و تحلیل تعاریف نظری سیمای سرزمین و کاربری اراضی، روش کتابخانه ای جستجو در منابع اینترنتی، پایان نامه ها و مقالات معتبر فارسی و خارجی استفاده شده است. در این پژوهش ابتدا تصاویر مورد نیاز تحقیق، در دامنه زمانی و مکانی معین از ماهواره لندست تهیه شد. دوره بررسی در یک دوره 30 ساله بین 1990 میلادی تا 2020 بود. این تصاویر از ماهواره لندست و سنجنده های TM وTIR/OLI در تاریخ های یکسان از سال تهیه شد. پس از اخذ داده ها، ابتدا تصاویر استفاده شده و بر روی آنها پیش پردازش انجام گرفته شد. سپس با استفاده از نرم افزارهای مورد نیاز نقشه های تغییرات کاربری استخراج شد. در مرحله بعد برای بررسی میزان ریسک اکولوژی هر طبقه وزن هایی برای هر طبقه در نظر گرفته شد و با کمک نرم افزار Fragstats 4.2 و بر اساس درصد بدست آمده مشخص شد که هر منطقه چه میزان ریسکی را دارد و با طبقه بندی میزان ریسک ها در محیط Gis به بررسی راحت تر مناطق بر اساس روند افزایشی یا کاهشی ریسک اکولوژی پرداخته شد. نتیجه گیری کلی از تحقیق با توجه به نقشه های کاربری اراضی برای ما نشان داد که از سال 1990 تا 2020 از مساحت مراتع و باغات و زمین کشاورزی و آب کاسته شده و بر مساحت فضای شهری و زمین بایر افزوده شده است؛ هم چنین در نقشه های ریسک اکولوژیکی نیز در طی همین دوره از سال 1990 تا 2020 از مناطق دارای ریسک خیلی پایین و پایین کاسته شده و بر مناطق دارای ریسک بالا و بسیار بالا افزوده شده است.The impact of urban land development on landscape pattern and ecological risk
IntroductionIran is also one of the countries that, in the last five decades, has faced the rapid growth of urbanization and the increase in migration to the cities, which has caused the sudden and unnatural expansion of these cities and the destruction of fertile lands and natural resources and compensation damages. Inevitability has become part of nature. As a result, there have been many changes in land use and land cover, and as a result, important structural disturbances such as the destruction of forests, the conversion of gardens and fields into built-up uses, and the severe pollution of the sea and rivers in the face of Iranian cities. It has led to a change in the function and disturbance of the ecological balance in the cities. Due to the increase in land use changes, mainly due to human activities, it is necessary to monitor vegetation changes, evaluate trends, and investigate their environmental effects for future planning and resource management. On the other hand, the lack of attention to land use changes in the last few decades has created many environmental problems, such as pollution of water, soil, etc., on the basis of which the investigation and analysis of land use on different scales with the aim of sustainable development and proper management of the environment and natural resources are essential. On this basis, in order to understand the mutual and complex relationships between cities and ecosystems in different regions, as well as to investigate the environmental effects of city growth beyond its physical boundaries, it is necessary to investigate the effects of urban growth and ecological risk on a wider scale than the city in question. The study should be done to clearly identify the changes that have been made in the landscape of that area. In this research, an attempt is made to examine the extent of horizontal expansion in the four cities of Urmia, Miandoab, Naqdeh, and Mahabad and to evaluate its effect on the landscape and its ecological risk. MethodologyIn terms of the general research approach and its nature, this research is descriptive-analytical and practical in terms of its purpose. Also, for compiling the theoretical topics of land surveying and land use, the library method, searching for internet sources, dissertations, and valid Persian and foreign articles have been used. In order to determine land use changes, Landsat satellite images were used, and initially, raw images were downloaded from the USGS website. In order to investigate the pattern of the landscape and the amount of destruction of the land and identify the changes in land use, there is a need to carry out this research over a longer period of time. Mahabad, Naqdeh, and Miandoab were obtained from the Landsat satellite. The time interval of the extracted images is 10 years, and the data of the images were selected so that they have the same season as far as possible in terms of vegetation. Accordingly, the images of the summer season (July) were used more due to the lack of cloud cover and pasture cover. Also, to examine the ecological risk of each class, weights were considered for each class, and with the help of Fragstats 4.2 software, based on the obtained percentage, it was determined how much risk each area has, and with the class The classification of risks in the GIS environment was done to more easily examine the areas based on the increasing or decreasing trend of ecological risk. Results and DiscussionThe high population density and the rapid expansion of urban uses in the four cities in question have significantly changed the structure of land use and the pattern of the regional landscape and caused a series of ecological and environmental problems. The results of the research show that the extent of garden and agricultural land in these four cities has been reduced by converting them to urban use. As we progress from 1990 to 2020, the ecological risks will also increase, which is the result of the rapid and unlimited expansion of these cities, which will lead to an increase in ecological risks and the deterioration of environmental conditions. In general, in all the cities under our study, agricultural land, gardens, and pastures have turned into wasteland and urban space, which has caused a significant increase in high-risk areas and environmental problems. It is necessary to improve the environment and protect the ecological balance of land use. Human activity causes significant changes in land use and affects the landscape of garden and agricultural land use. In recent years, with the trend of increasing population and changing the uses of pasture land, gardens, and agricultural land to barren land and especially city space, it has brought environmental risks to different areas. Ecological risk assessment helps us identify the amount of change in each region and investigate which regions have high or low risk. According to the prepared maps, the amount of risk in each region is divided into 5 categories, which include areas with very low risk, low risk, medium risk, high risk, and very high risk. How much it will be paid. It should also be noted that the validation numbers used in the field of ecological risk, which are weighted based on each land use in the area. ConclusionThe focus of this study is on land use changes and ecological risk on four cities in four plains leading to Lake Urmia. The results of land use changes and its analysis show that many changes have occurred in the land use of the studied urban areas. The results of the investigation of the urban growth pattern of the four cities in 6 layers of gardens and urban green space, agricultural land, barren land, urban space and pasture and water shows that in a period of 30 years, the area of pasture, gardens, agricultural land and water has decreased and increased. The area of urban space and wasteland has been increased. This process has continued from 1990 to 2020 and has caused many high-quality agricultural lands to change use. However, there are differences between the studied cities. For example, the city of Urmia has undergone more changes than the city of Mahabad, but the general result of the studied cities shows a lot of land use changes around Lake Urmia. Ecological risk assessment was classified into five risk categories from very low to very high risk. The results of ecological risk-taking show that between 1990 and 2020, the level of risk has decreased at a low level. Urmia city has increased from 52% to 23% and Naqdeh, Mahabad and Miandoab cities from 25%, 57%, 27% to 8%, 32%, and 4% respectively, and in contrast to the risk in the very high class, there has been an increasing trend and the cities of Urmia, Naqdeh, Mahabad and Miandoab reached 39, 32, 16 and 13 percent from 8, 9, 3 and 4 percent, respectively. These results show that the ecological risk of the studied cities has increased in the last 30 years. One of the important effects of this increase in ecological risk will be the negative impact on Lake Urmia, which will have a reciprocal effect on the increase in ecological risk.
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