عنوان مقاله [English]
After the Industrial Revolution, advancement in industry and technology coupled with population growth and Rural-Urban migration induced the extreme expansion of cities. Moreover, the rapid growth of urbanization in coastal areas and conflicts of interest between the stakeholders have imposed an extreme ecological pressure on this fragile ecosystem; which implies the contradiction between the cities and the coastal environment. According to the records of Statistical Centre of Iran, the coastal city of Deylam which is located in Bushehr province has been struggling with population and migration growth during the last six decades. Since the common expansion pattern of coastal cities is "linear" and they are distributed along the coast, it is obvious that any effort against the urban sprawl of coastal cities will profit the coastal ecosystem. In this research by using the quantitative data and descriptive-analytical method, the urban sprawl of the Deylam coastal city was investigated for an approximate time span of 10 years. For this purpose, at first existence of the urban sprawl in the studied area was assessed by Shannon's entropy method. Subsequently, the share of horizontal urban growth which made the Deylam city to be faced with urban sprawl was determined using the Holdren Model. Afterward, for the first time by employing the Digital Shoreline Analysis System in studies of horizontal urban growth, the rate of horizontal growth for the time period of investigation was calculated. Eventually, by deducting the share of urban-sprawl growth (which is calculated by Holdren model) from the total growth of Deylam city, the optimum size of Deylam city was achieved and then provided by maps. ArcGIS 10 was used to produce these maps. It is worth mentioning that according to the calculations of Shannon's entropy, at the beginning of the investigation time (i.e. February 16, 2005), Deylam city was highly expanded by having the 80.14 percent of its maximum possible value of urban sprawl. Moreover, based on the Holdren model, 62.9 percent of the urban growth of Deylam city is due to the population growth; therefore, 37.1 percent of the total growth is responsible for the urban sprawl of the city. Results showed that the Deylam city in its northern and southern edges has experienced a growth rate of 19.08 and 23.11 m/year with a standard deviation of 4.5 and 4.1, respectively. In its northern edge, the growth rate of 7.08 m/year is due to the urban sprawl and 12 m/year is because of the population growth. In the same way, in its southern edge, the growth rate of 8.57 m/year is due to the urban sprawl and 14.54 m/year is because of the population growth. The western and eastern edges of Deylam city did not develop during the investigation period of study because there are some natural barriers in these parts. Since the provided framework which is practiced in this study is easy to apply and the procedure of the calculations is clear, it may have great contributions in projects of confronting the urban sprawl problems.