عنوان مقاله [English]
In the recent decades, rapid horizontal expansion of cities in all countries around the world has been faced with serious challenges. This phenomenon is not only the issues largely affected by urban policy, but the consequences of the intensification of economic, social, political, and environmental management of the communities involved. This was due to the concerns of the developing countries, particularly after World War II, to take measures to resolve the crisis or to inhibit. The main areas of policy measures are tall building, mass, changes in tax laws, rules and regulations for the use of land, improvement and renovation of old texture. There are two competing models of sustainable urban development. On the one side, there are those who support compact cities. The idea here is that large, dense and concentrated cities will support the principles of sustainable development. However, on the other side, there are those who support the green city, i.e., a more open type of urban structure, where buildings, agricultural ﬁelds and other green areas form kind of mosaic-like pattern. The rapid development and spread of the urban and adopting policies and strategies to increase density dispersed urban growth and led to the entry of such amendments, compact city. There is a problem that the term urban sprawl is widely used in many disciplines dealing with urban development and urban form. The smart growth has been implemented in the literature. Compared with the pattern or distribution of horizontal growth, more and better benefits of smart growth pattern can help improve the quality of life in cities. Smart growth will try to accommodate urban development within the existing framework, developed to prevent uncontrolled urban expansion. In addition, it can also contribute to improvement of the community, while the horizontal growth pattern is not consistent with sustainable urban development, the negative consequences of such a model, including the loss of agricultural land around the city, and soil degradation and water pollution, air pollution, increase in the cost of municipal services, increase in travel time to the city, and the subsequent increase in fossil fuel consumption, social segregation, lack of land use or irregular use of resources . The extension of the distance between the place of residence, place of business, commercial centers, and recreation centers makes it more dependent on private cars and people are forced to travel long distances to use private cars. Use of personal vehicles due to environmental factors such as pollution (air, noise and radio ...) leads to higher energy consumption. This also leads to wasting time, money and mental and neurological disorders. Accordingly, this study sought to examine Kermanshah urban growth pattern in the last few decades in terms of sustainability.
The methodology of this article is based on descriptive method. With this approach to urban sustainability, it explains the differences between two types of sprawl and compact urban development. This study has used Gini coefficient, entropy relative Shannon for detection of unbalanced distribution. On the other hand, other indicators like Gary and Moran coefficients have been used to determine the degree of concentration or density and distribution of population and employment based on the spatial correlation. Finally, the model is used to measure urban growth model Holdren.
Results and Discussion
The results of this research show that the population density of Kermanshah has dropped during the past decades. Between 1956 and 2011 the population density of this city decreased from 414 persons per hectare to 81. Other results show growth pattern of the city of Kermanshah somewhat scattered, according to the calculations made by the coefficients of Genie and entropy relative Shannon and inequality and imbalance in the distribution of population in urban areas. The data obtained from Moran and Geary coefficients indicate that the growth pattern of the city is closer to the random pattern. The calculations made by Holdren model also show that physical growth of Kermanshah from 1956 to 2011 is only 55 percent of population growth and 45 percent of the growth is horizontal (sprawl). These results indicate that during this period, the city is faced with reduction of net density population and increase in per capita gross of land.
This paper addresses the issue of urban growth pattern of Kermanshah in recent decades in the direction of sustainability. The questions based on the research conducted, is whether it is possible to achieve a sustainable urban form? What is the relationship between sustainability and urban form? The study has shown that the calculations were based on the growth pattern of the city of Kermanshah. Gini coefficient and the relative Shannon entropy is somewhat sparse and with inequalities and imbalances in the distribution of population in urban areas. It is evident that the figures obtained from Moran and Geary coefficients indicate that the growth pattern of the city and closer to a random pattern of distribution tends to be Holdren model. The calculations have revealed that 45% of the city horizontal physical growth (sprawl) has been as the horizontal distribution pattern of urban growth in developing countries as well as developed countries. It is becoming more common. The main features of this model include: relief and fled and dispersed development, commercial strip development, low density, and single-user development.
The results also indicate that the growth pattern of the city of Kermanshah has tendency toward fragmentation and inequality and imbalance in the distribution of population in urban areas. This is a major cause of instability in the city given the importance of direct development towards sustainability; the need to change the scattered pattern is emphasized on compact city.