Comparative study of Rank-Size Rule and Urban Differential model in hierarchy of spatial distribution of people in human settlements with focus in small town's roles

The rapid growth of urbanization, the spatial distribution of the population in the area has been uneven. Focus facilities and services in metropolitan areas and the lack of balanced growth in the medium and small can lead to inequality of population in the area and class level difference in communities. It also appears to rule out the distribution of population in cities, based on rank-size had significant from the normal urban differential does not match the model. This study sought to implement the model of urban differential and rank-size rule in the province's urban network. Aims to provide guidelines for the creation of a balanced hierarchical system with an emphasis on small towns that recently the city has been given to them. The study is applied and descriptive and analytical nature. Using Mehta four cities index and city evolution index network process benefited during the analysis and studies of population and housing census information 6 times leading up to 1390 and 30 city in Hamadan province. The results showed the weakness of small towns, middle and long distance rank-size rule is the first city in the normal line. Medium-sized cities have stopped growing urban areas in the early stages the weakness of central cities in terms of both population is the multiplicity of small towns. Population survey of cities and a lot of them over the last 50 years indicates a policy has been ineffective villages to small towns in the province. Because the model of urban differential must be addressed to strengthen central cities and small towns development policies are on the agenda.