Introduction
To steer the city towards sustainable development, understanding the pattern of physical-space development in cities and having knowledge of the ensuing spatial developments in their surroundings became important considerations. Other developments, together with spatial flows, animate the space around large cities, especially rural settlements. Notable among those concerning physical and spatial developments around the metropolises are urban sprawl, environmental degradation, urban pollution, changes in the roles and functions of villages, and loss of agricultural lands. These developments can be witnessed in the surroundings of Tehran metropolis. Traceable physical-spatial transformations are apparent in various forms in the southern reaches of the metropolis and in Islamshahr city. Population growth, internal migrations, need for housing, increase in economic and industrial activities, and expansion of transport networks are some of the drivers of peri-urban development in Islamshahr city. Each of these drives, whether in isolation or in combination with others, exert some influence in their own right upon the spatial and functional structure of the city and contribute significantly towards the working of development processes. However, such development is not necessarily in a way that is coordinated and sustainable. Careful and systematic planning is needed for such development to avert negative consequences, for example, increases in pollution, decreased quality of life, and spatial inequalities (Nuri Kermani et al., 2014). Accordingly, in this article, the aim will be to analyze and identify all causes responsible for the development of urban fringes in Islamshahr city so that based upon that, the various means may be designed and proposed to attain a desired form of development. Therefore, the primary question in regard to this concern is: What drivers and key factors play a role in the development of peri-urban spaces in Islamshahr city, and how can these drivers be used to create scenarios and achieve a sustainable development model?
 
Methodology
Descriptive-analytical research, on-the-ground exploratory data analysis. The type of research data is quantitative and qualitative. This means it is mixed in terms of type. The method of data collection is library and field. The research statistical population is the total population of Islamshahr city (villages and cities) under legal boundaries according to the total general population and housing census for 2015.537,620. The sample size was determined by Cochran's formula with capacity of 384 people. The random sampling method was simple. Future research in this section will be about statistical sampling method through Delphi procedure. Data have been analyzed at several levels. The first level in the analysis of research data included descriptive statistics and T-Test. The questionnaire was analyzed by this method. At the other data level analysis, future research method has been adopted. The data analysis in this section has been conducted through Mic Mac software.
 
Results and discussion
As a result of the analysis of the conducted interviews, closeness of Islamshahr city to Tehran is the most determinant factor in the physical-spatial changes of Islamshahr city. Next are the existence of Tehran-Saveh and Islamshahr-Ahmedabad communication road, establishment of large industrial centers, and land and real estate exchange in Islamshahr city. These remaining three are quite vital for the physical changes and transformations of Islamshahr city. In what follows would be the other studied components in the list of importance. Results and processing of the above graphs revealed that eleven key factors out of the forty included the Mic Mac software as key influencing factors on future physical and spatial developments of Islamshahr city. Now the results show that within 12 uncertainties are the most important ones. Thus, based on 12 uncertainties, four different scenarios will be prepared for future physical-spatial developments of Islamshahr city. Below are the four scenarios. The first scenario is the most probable to come true, with a score of 25, in the year of horizon Islamshahr region. Characteristic of this scenario is the increase in constructing agricultural lands followed by an increase in residential and activity capacities (intermediate hypothesis) and then the activity center of machinery exhibitions in Islamshahr is followed by an increase in employment and service capacities (optimistic hypothesis); thus, two intermediate and optimistic hypotheses characterize this article.
 
Conclusion
The results of the research indicate that the city of Islamshahr is in the shadow of population and activity overflows as brought about by its proximity to the Tehran metropolis. This connection has caused the passage of the Tehran-Saveh axis for the passage of time to develop connections from which the establishment of residence and activity spots could be with respect to and adjacent to such axis. This is for purposes in which rural areas have rapidly turned into urban areas through absorption within the population outflow of the city of Tehran or have been attached to the neighboring villages, thus forming a large urban area. The Islamshahr, being a cheap land and near the Tehran city, has attracted several kinds of industries and production-workshop activities into it. These conditions still prevail, and the studied elements show that proximity to Tehran and the existence of the Tehran-Saveh axis remain important factors for the attraction of population and activity. Yet, the emergence of other parameters like dominance of residential, activity and industrial centers has thickened this situation, and a new kind of spatial organization is born here. The studied models have shown, indeed, that there are two space-generating processes and patterns in the area. The first is the model toward developing and improving the area according to the town-building and street construction agendas of planned progress and implementation of organizing plans, but the second pattern conventionally would mean that the conditions of informal settlement and environmental pollution induced by concentration of industrial activity, with each element emerging from traffic, would continue and fuel the living conditions as well as spatial organization of this region.
 
Funding
According to the responsible author, this article has no financial support
 
Authors’ Contribution
Considering that the present article is extracted from a doctoral dissertation, the contribution and role of the first author was as the supervisor, the second and third authors served as advisors, and the fourth author was the doctoral student.
 
Conflict of Interest
Authors declared no conflict of interest.
 
Acknowledgments
 We are grateful to all the scientific consultants of this paper.