The role of spatial changes of employment and activity in creating the lack of appropriate urban cores (case study; Tehran)

Background and objective: The spatial structure of cities depends on the different and mutual relationships of all forces and factors in the city. These factors include market forces, activities, urban infrastructures and various services, which always have a complex and reciprocal relationship. In today's world, one of the basic challenges in cities is to create a balanced spatial structure that plays an important role in sustainable development. Development and creating an efficient multi-core spatial structure in metropolises like Tehran requires a balanced spatial distribution of population and activity cores. The factors of population and activity are the main elements of the spatial structure that have a direct and main effect on the creation or non-creation of desirable urban cores.  The Aim of this research is to evaluate and analyze the spatial structure of Tehran metropolis from the perspective of population and activity indicators in order to determine the state of balance or imbalance of the spatial structure as well as the state of urban functional cores.  Method: The research method is descriptive-analytical and based on spatial statistics calculations. The information and data used are collected from official and library sources and include information related to urban activities in the field of employment. The activities are listed in seven (7) main industrial, commercial, administrative, educational and recreational, cultural and medical categories and are considered as functional cores. In order to analyze the distribution of functional cores of activities and the population of Tehran and the spatial patterns of activities, the methods of mean center, standard deviation ellipse, nearest neighborhood mean and geographical weighted regression (GWR) have been used. Findings: The results of this research regarding the distribution of the spatial structure of the city of Tehran based on the indicators of activity and population and the relationship between these two indicate that the activity nuclei are in the form of a single nucleus and in some components in the form of multiple cores and the pattern of distribution of functional cores in the city has a cluster pattern. Conclusion: Based on the results of geographic regression, there is an effective relationship between functional cores and population distribution in the city of Tehran, and this situation causes and aggravates traffic problems and congestion in the metropolis of Tehran. In this regard, it is necessary to strengthen the functional role of areas in which the relationship between these two indicators is weak (Region's 15-22-5-18) in order to reduce the burden of traffic and congestion in other saturated areas of the city (Region's 3-6-7-11-12) And also be strengthened the multi-core spatial structure of the city.