Spatial Analysis of the Urban Hierarchy Based on the Formation of Urban Staire System in Iran

In the urban hierarchy, besides of urban primacy, there is some reasons that led to an internal order among cities and it create a hierarchical system where in cities make up some groups. These groups are recognizable via population gap on linear curve. Findings show that urban primacy is a dominated phenomenon in urban system of Iran. Of Course it appears in different pattern which can be classified in weak, medium and strong level. Beside of urban primacy dominance, there is another dominated system called stair system. Study of urban system in Iran confirms the existence of stair system in urban hierarchy in both national and regional level. This system divides the urban hierarchy into several urban groups. The group mate cities separate from upper and lower level cities due to population gap and it seems that they make a new form of urban hierarchy. In this system, cities are able to classified into several groups and each of them have caused more homogenous hierarchy system than entire of urban system in region. One of the most important issues in this area is the Identification of main factors causing it. Because the variables that are been studied in this research are not the main factors in the creating of stair system. Study of this system and mechanism of its function, can lead to identify new dimensions of urban hierarchy system at the other scales.