عنوان مقاله [English]
In recent decades, research on land use/land cover change has become an important aspect of global change, or global warming studies, since land use/land cover change is a major factor for global change because of its interactions with climate, ecosystem processes, biogeochemical cycles, biodiversity, and, even more important, human activities.
Dynamic urban change processes, especially the tremendous worldwide expansion of urban population and urbanized area, affect natural and human systems at all geographic scales. Todays, the rapid growth of urban areas has led to complex problems, including traffic congestion, environmental pollution, reduced open space, the deterioration of old downtown centers, and unplanned or poorly planned land development. Urbanization both in population and spatial extent, transforms the landscape from the natural cover types to impervious urban lands. This phenomenon is one of the most important factors that changes land surface leading to modification of receiving environments which are usually composed of natural cover. Rapid urbanization in recent decades and land use changes in urban periphery especially in big cities are the fundamental challenges of sustainable development in the world. Increasing of urbanization tendency and rural – urban migration, unsuitable management of urban development caused that the green spaces and gardens in urban periphery and in inner areas changed to urban profitable land use and especially residential areas. In this research urban expansion and rapid urbanized areas and effect of these challenges in urban green spaces are analyzed.
To address these urban problems and to identify approaches for sustainable development, many researchers have focused on evaluation urban land-use changes. In this research, we selected Tabriz City for analyzing as a case study. Urban green spaces changes in Tabriz analyzed using Landsat satellite images for past decades. Satellite remote sensing provides an important source of land use/land cover data and can be utilized to monitor the changes in these data efficiently. In the first, we were made geo reference and necessary correction for satellite images and then we classified images using Erdas imaging 2014 software. For Quantitative assessment, the maps export to Arc GIS 10. 3.1 Software and finally, the green spaces land use maps and tables are produced. For analyzing green areas in future, green spaces changings in 1410 are modeled using Artificial Neural Network (ANN) base of past changes pattern. Artificial neural networks are able to approximate accurately complicated nonlinear input–output relationships. Like their physics-based numerical model counterparts, ANNs require training or calibration. After training, each application of the trained ANN is an estimation of a simple algebraic expression with known coefficients and is executed practically instantaneously. The ANN technique is flexible enough to accommodate additional constraints that may arise in the application.
Results and discussion
Result show that, urban expansions to per-urban and especially in green areas and orchards have been made major changes in urban green spaces. Evaluation of green space areas from 1355 to 1385 show that the green areas are decreased from 5916.53 to 4373.96 hectares. In 30 years periods, 1542 hectares of green areas destroyed and percent of green areas in Tabriz limit, reduced from 23.31 to 17.23. The land use changing in this period has been slowly. But, the green rate damages, in last decade is too fast and urban green areas in 1395 is 1709.02 hectares that contain 6.73 percent of city limit (25000 hectares city limit). In last decade, 2664 hectares in Tabriz green spaces, change to other land use and especially in 1385 to 1390 the rate of changing was faster and most of 50 percent of green areas in this period are demolished. In ANN modeling results, Tabriz will lose 1076 hectares of green areas from 1395 to 1410.
Therefore, the results indicate that the lack of proper planning of Tabriz's urban development in the last half century and especially in the past decade has caused irreparable damage to the green spaces of Tabriz, and will continue the trend in the coming years will threaten sustainable urban development and ecological balance of Tabriz city