Regional Plans and Centralization in Spatial Structure of Urban Systems Case Study: Kermanshah Province

The spatial structure of urban settlement system is affected by two groups of factors, namely physical and non- physical ones. The impact of physical factors on creation of urban systems was very impressive in the past. However, nowadays the main role is played by non- physical factors. Some of these factors are regional development plans which their impacts on urban system formations are important either in small or large scales of evaluation. Province of Kermanshah and its capital city also called Kermanshah is a remarkable example at Mid- Zagros region as the pole of regional growth during the last five decades. The region has been a target for a wide range of decisions, actions, and policies of regional development in west of Iran. The urban system of Kermanshah province with its imbalance size distribution is an example of the most imbalance and non- sustaining urban systems around the country. Having about one million populations, Kermanshah city is a dominant and concentrated urban pole for the whole province as well as the region. At the same time, the second largest city of the province has a population less than 100,000 or one- tenth of Kermanshah city population. More interestingly is the smallest city, Somar with only 20 residents. The existing gap of size distribution of cities with its Primate City Index which is 0.81 not only in regional scale but also in national scale is very high abnormal. What is considered in the present paper is the role of regional plans in centralization of urban system which results in imbalance spatial structure of urban settlement’s systems. The paper also shows the pivotal function of city-oriented or urban centralization covert in classic views of regional development and regional planning especially the intensive tendency of such views towards the higher levels and head of urban network. It reveals one of the main basic reasons of rapid urban expansion, also polarization of urban system, divergence of settlement system and its harmful consequences on spatial system of the country and its regions with a provisional approach.