Analysis of the Spatial Structure of Urban and Rural Population (Case Study: Zanjan Province)

Introduction
City as a set of human activities, natural environment, economy, and population is one of the important elements of the space. The population is distributed on the earth's surface to form urban and rural settlements. Populations of settlements have been distributed in various forms. Population distribution and the distribution of settlements in the habitable surface of the earth is not the same.  A large part of the population is distributed in some certain areas of land. In the modern times, it is possible that space and spatial organization can solve the problems resulting from lack of proper distribution of population. One of the latest views in planning in the world is spatial and spatial structure.
In this framework, we need to survey the needs, spatial specifications and spatial structure elements. One of the important elements of spatial structure is population. Population is one of the basic elements in economic, social and cultural plans. Therefore, knowing the population, its structure and spatial expansion is a tool to make decisions and planning.
In fact, spatial structure of population expansion is a guide key for long term economic projects. The expansion and mobility of population is very applicable in   planning for geographical region. Many problems resulted from false planning is resolved. One of the programs to analyze space and spatial organization is spatial planning. The purpose of this type of programming is to achieve proper distribution of population and activities on the earth surface, and accept population equivalent with its natural and economic power. This form of planning is the best complement to useful planning in the country. In fact, the spatial planning has a macro and global vision. Spatial planning considers all regions together.
Hence, in this research we tried to determine a spatial structure for population in Zanjan province. This paper explores the spatial distribution of population in urban and rural settlements in the zanjan province by space tools to emphasize on system and analysis of the elements influencing the spatial organization of the region, (the three elements of space, activity and population), particular emphasis was also on population element.
Methodology
The research method is descriptive-analytical. The resources used are mainly documents and secondary data sources, such as census data, maps, etc. They  were obtained through library studies and documents. Study area, the Zanjan Province and has been collected from library documentation. It involves collecting all documents, reports and related data related to spatial organization of area and population, especially in the province. To analyze the spatial organization, we used spatial organization models in this paper. These models include the rank-size model, levels distance limit model, urban settlements classification scheme based on the classification of land, and average nearest neighborhood model. This is to survey the current population expansion status in Zanjan province.
Results and Discussion
The results of this study showed that one of the main problems of the current is disparities and imbalances in the spatial distribution of population in urban and rural settlements. As one of the most important characteristics of spatial pattern of population settlement in population of Zanjan Province is population density in cities and the rest of the province.
About 90 percent of the urban population of the province  is living only in 4 settlements and only 10 percent in 12 cities. Thus, the concentration of population in 4 first cities of the province and small share of population in other urban and rural areas caused by the distribution pattern of population in the province is imbalanced.
The problem related to the distribution of population in the province includes dissociation in the urban hierarchy and insufficiency of settlement hierarchy, imbalance between the city and large proportion series (zanjan city) and end city (halab city), the rapid growth of the urban population relative to rural population, and increase in rural-urban migration.
Conclusion
All of the problems lead to concentration of population in small areas of the province.  Spatial patterns of population settlement in the province have been disparate and unbalanced. It can be said that the effort to create balance in the pattern of population distribution and reform of the settlement of hierarchy is necessary  today.  The continuation of current trends will increase the problems resulted from these issues and will cause misuse of natural and human resources for development of the province. It can also create prosperity for the residents of the province.