عنوان مقاله [English]
The increase in population and the expansion of urbanization have led to increasing pressure on the land and has caused the destruction of land around the cities and has been a major challenge to urban planning in recent decades. The present research is based on descriptive-analytical method and is applicable in terms of purpose. To analyze the spatial development trend of Shiraz metropolitan area, satellite imagery from 1365 to 1395 was used and for modeling changes in 1410, effective parameters in urban development and land transformation model were used. The results of the analysis of satellite images for the years 1365 to 1395 indicate the increasing changes in agricultural use and green spaces to land use. And in the course of 30 years it has destroyed more than 508 hectares of green space and more than 3373 hectares of agricultural land. The results of the Holdoren model indicate that 59 percent of the city's physical growth was attributed to the city's population increase and 41 percent to the horizontal and sparse growth of Shiraz. Continuing this trend, the future development of Shiraz will face increasing environmental and ecological problems. And with this trend, urban green spaces and more agricultural lands around the city of Shiraz will be under construction until 1410, and urban problems will double. Also, after 1410, new urban development will require an increase in urban areas and, as a result, environmental degradation around the city and agricultural land.
Population growth and urbanization have put increasing pressure on the land, causing the destruction of land around cities, and have been one of the major challenges in urban planning in recent decades. In recent years, the development of sprawl and the growth of low-density housing along the transportation corridors have caused many problems and environmentally inefficient housing patterns and have had a negative impact on the periphery of the settlements. Analyzing the trend of spatial development of Shiraz metropolis and evaluating the uneven growth of the city with the existing population can reveal more effective factors in the uneven development of Shiraz. In the past two decades, it seems that the development of the periphery of the city has been the focus of most city managers and decision makers. This is supported by the development of the city in the northwest and other peripheral areas with favorable agricultural lands and gardens. The main purpose of the study will be to examine the urban spatial development of Shiraz in the past decades and what pattern it has followed and its impact on the future development of the city.
The present study is an applied developmental and a descriptive-analytical methodology based on library studies and field studies. Satellite imagery and available statistics have been used to analyze urban land use changes in the past decades. To study and evaluate urban development and to match urban expansion with urban population growth, the Holderen model has been used and analyzed based on this urban sprawl development model over the past half century. Research software include ARC GIS, ERDAS, Matlab. Also, land transformation model is used to model and predict urban land use changes.
Analysis of satellite images in the context of Shiraz city development process was performed in the land transformation model. After preparing the data in the ERC GIS, ERDAS IMAGING software suite, data were prepared in ASCII format for entering the model. In the learning cycle evolution model, learning was performed using root mean squared results, adaptation metric percentage, and kappa coefficient. The learning rate was evaluated from 100 to 30,000 cycles, the error rate was reduced to 10,000 cycles and the Kappa and adaptation coefficients were adjusted. Therefore, the basis of learning to avoid over-learning was selected in the 10,000 cycle, with RMS, PCM and KC of 0.693838, 0. 135858 and 75.788646, respectively. The results of the study from 1986 to 2016 indicate that during this 30-year period 25488 cells were developed 50 by 50 square meters and the result was used as an input to predict future development.
Following the development of the city in the past, most of the potential development has occurred on the west and northwest, and the southwest side has received some development. And the built-up areas of the city will increase by 27 percent in the year, from 12272 hectares in 2016 to 16501 hectares in 1410. Greenery will be reduced to 1276 hectares by 63% demolition and will have more severe forecasting horizons this year. Agricultural and wilderness areas will also decrease by 69 percent to 1545 hectares. But in the mid-rise development model, the amount of land use change reflects a 52 percent change in agricultural and waste land. However, no change has been made due to the conservation of existing urban green space designated as protected areas in the model.Built areas also accounted for 20% of the more rational development, reaching 15020 hectares. Therefore, using this model, not only will urban sprawl be halted and urban landscapes protected, but also the improvement of inappropriate urban land uses will be prioritized and a dynamic urban form will be formed. The results of Holderen model in Shiraz show that between 1335 and 1395 about 58.9% of the city growth is related to population growth and the remaining 41.1% is to the horizontal and spherical growth of the city which results in a decrease in gross density. Population has been the increase in GDP per capita and, finally, the horizontal expansion of Shiraz.
The results show that the perception of land as a commodity and private property has strongly influenced the urban development of Shiraz and has expanded the city around and increased the urban area. In the IDP model, compared to the PDP model, the built-up area is reduced and the agricultural and green space degradation is reduced. The user class built in the IDP model is 15020 hectares, while in the PDP model it is increased to 16501 hectares, indicating that 1481 hectares is the difference in models of urban development, representing an 11 percent difference. Also in the IDP model, the green space user interface does not change. While in the PDP model, 37% of the degradation was achieved, and urban endogenous development in the IDP model reduced the development pressure on the peripheral and agricultural land, reaching 52%. But in the PDP model, more than 69 percent of this type of user changes. This means that in the IDP model, 1181 hectares of this land use have been preserved. Helderen's results show that between 1335 and 1395, about 59 percent of urban development was due to population growth and 41 percent to urban sprawl. Is. With the continuation of this situation and the lack of a proper policy to maintain this land use, the sustainable development of Shiraz will face serious risks. The results indicate that as this type of development continues, more urban green areas and agricultural lands around the city of Shiraz will go under construction and alleviate existing urban problems. Also after 1410, new urban development will need to increase the urban area, resulting in the destruction of the environment around the city and agricultural land.