عنوان مقاله [English]
Fast and uncontrollable urbanization growth causes loss of lands and its recourses. This leads to a decrease in green areas, open spaces and serious environmental and social problems. Therefore, an essential step to urban planning, management and evaluation of its effects is to simulate physical development of the city. The aim of this study is to understand parameters of physical development in Ilkhichi city with regard to sustainable spatial development of urban issues from ecological and environmental perspectives in the next two decades.
Changes in the land uses in 1984-2011 have been evaluated with emphasis on sprawl expansion of Ilkhichi city using Landsat 5 multi temporal satellite images and object-oriented techniques. Based on the results, urban area of Bonab, with an area of 94.59 hectares in 1984 has reached to 438.57 ha in 2011. About 195.84 hectares of the mentioned lands has developed on the gardens and agricultural lands. This demands management of future development based on the principles of sustainable development. Therefore, effective factors of physical development in Ilkhichi urban area have been classified into 12 layers. The LTM method has been employed to produce the possibility of urban development map. After predicting the future pattern of urban development in Ilkhichi city, the protection of gardens and green spaces strategy in the urban development process was operated using hexagonal layout of possibility of urban development map..
Rapid urbanization brings opportunities to new urban developments. However, it also causes serious losses of arable lands, as occurred in other developed countries. The term urban sprawl is so cloudy and confused that more precise language is needed to characterize what is bad urban growth.
In order to keep ecosystems functioning well, it is necessary for environmental researchers, managers, and decision makers to understand the spatial dynamics of an ecosystem. Importantly, remotely sensed imagery provides an efficient means to obtain information on temporal trends and spatial distribution of urban areas for understanding, modeling, and projecting land change.
In this study, changes of land use are analyzed in Bonab County using satellite images during 1989-2005. We have also proposed recommendation for reducing settlement sprawls and environmental problems in this area.
Change detection is an important process for monitoring and managing natural resources and urban development because it provides quantitative analysis of spatial distribution in the area of interest. For monitoring the changes in land use of Ilkhichi, TM digital data of Landsat have been used in this study. The path/row number of TM and ETM+ imagery is 168/34. Main reason to use TM and ETM+ data was that of high resolution images for time series is not available to extract green area land use. The Land Transformation Model is a land use forecasting model as well as a tool that can be used to examine the spatial and temporal aspects of driving forces of land use change. The model uses a set of spatial interaction rules and machine learning, through neural net technology, to determine the nature of spatial interactions of drivers such as transportation, urban infrastructure and proximity to lakes and rivers that have historically contributed toward land use change in the past. Effective factors of physical development of Ilkhichi city based on research literature is identified in 12 indicators and artificial neural network based on LTM Model for preparing Urban Development probability map.
Results and discussion
In 1984-2011, based on Change detection map and initial state and final state matrix, barren land area has decreased from 66.627 hectares to 52.479, the built area has increased from 59.94 hectares to 57.438, agricultural land has decreased from 572.76 hectares to 387.90 hectares and garden land has decreased from 33.93 to 22.95 hectares. In this period, the population of the city has reached from 7446 to 15231. This means reduction in the population density from 78 to 34 people. Based on the Holdern model, sprawl index of Ilkhichi city is 53 percent and the biggest role in the development of buildup area belongs to reduction of farming and agricultural lands. About 195.84 hectares of the mentioned lands has developed on the garden and agricultural land. This involves management of future development based on the principles of sustainable development.
After predicting the future pattern of urban development in Ilkhichi city, the protection of gardens and green spaces in the urban development process was operated using hexagonal layout of possibility of urban development map. This can provide the necessary space for the development, extension of the natural green belt about 5 km long, restriction of urban development in buffer of green belt, protection of the ecological reserves of Ilkhichi city, and sprawl expansion control. Urban managers are able to decrease the horizontal expansion for detailed monitoring on proposed green belt, the use of mass production methods and the high-rise building (Compact City), the use of low-yielding land available inside the city (Infill development), and the urban development far away from the agricultural land.