the analysis of factors influencing physical urban growth pattern for large cities of iran

the hastening increase in the population of the cities ,lack of urban infrastructures ,shifting the land use and the consequent vanish of ecologically valuable lands in the countries ,industrial pollutions ,illegal settlement in the suburbs and other human activities which have influenced the growth of cities in iran too ,make it necessary to study and analyze the growth of rasht(the capital of the gilan province in the vicinity of caspian sea which is one of the large cities in iran) urban growth and its driving factors are important topics in recent urban research analysis. several physical, economical and social factors influence the urban growth while they have nonlinear and complex relation. the goal of this study is to define and recognize the urban growth system, affecting factors on urban growth, quantize the relation between the urban growth and the driving factors and analyze the spatial growth patterns according to historical land use change for the city of rasht, assuming that some special driving factors and local patterns which are consistent with geographic, economic, physical and social structure of the city, have influenced its growth. since the factors of urban growth are unique for a given case and past studies were not concentrated on comparative analysis of urban growth, the present research focuses on determining the most important factors affecting city growth through modeling and compare the common and divers points of urban growth in rasht with other studies. for this purpose, by reviewing the theoretical concepts associated with urban growth, quantative and measurable criteria are developed as proper frameworks to study the influencing factors on the city growth. this paper describes the urban growth model through “logistic regression” which based on the theories of urban growth, contributes to determination of growth mechanisms at different time phases and recognition of driving factors and introduces two series of influencing factors on rasht urban growth: 1) factors with favorable effects including: slope(%), distance from nearest markets, farm lands and less populated areas. 2) factors with unfavorable effects including: distance from main roads, residential areas and industrial centers, lands covered with trees (forest) and areas with expensive lands. finally it was found that the specifications of physical growth pattern of rasht depended not only on the existing situation of the pattern, but on the factors influencing it as well. the most important driving factor of rasht urban growth is its “roads” which could be most observed in the south along the rasht-tehran road toward the industrial town. it shows that the mutual effect pattern of land use _ transportation will play an important role in the future planning of the city. also unlike the forests, farm lands are progressively changing into town lands that should be prevented through feasible and practicable planning and investigating the political and managing factors. the results of this research could be suitable means to analyze and compare pattern and factors influencing on urban growth of rasht with other large cities of iran to be utilized by urban planners and managers .