check the status of urban hierarchy of lorestan province from 1986 to 2011

extended abstractintroductionone of the basic challenges of governments, especially in developing countries, is to organize the desired national spatial structure in the changing urbanization. such a structure allows us to divide economic and social functions in the urban and regional hierarchy in a balanced manner. in most provinces and territories of iran, the urban hierarchy has formed completely cluttered and irregular, and the tasks of cities are unknown, that has led to several problems. this study examines and analyzes the urban hierarchy of lorestan province from 1986 to 2011. the main research method is descriptive-analytical, and the research type is applied-developmental. the required data were collected with the documentary-desk method. the study aims to evaluate urban hierarchy changes in lorestan province from 1986 to 2011. the entropy model, the rank-size rule, class difference limit model, and nearest neighbor are used for data analysis. the results indicate that the urban network of lorestan province from 1986 to 1996 has had an almost balanced state in terms of special distribution of cities but from 2006 to 2011, this balance has disturbed and the spatial distribution of cities has become unbalanced. one of its major reasons is the emergence of very small towns (village-towns). in addition, in terms of distribution of urban population based on the class difference limit model, there is a statistically significant disharmony and disruption during the studied periods in the cities of the province.methodology this is a descriptive-analytic research of the applied-developmental type. the required information was obtained from library sources and from collected documents. statistics concerning the study, and related to the period from 1986 to 2011, were collected from the office of the governor general of lorestan province and from the statistical yearbook of the statistics center of iran. the “rank and rate,” “limit of class differences,” “entropy coefficients,” and “nearest neighbors” models were used to analyze the statistics. results and discussion results obtained from the nearest neighbors model are in agreement with those found by taleshi et al. in the study they carried out on ardabil province, in which it was shown that there was a balance among the cities in ardabil province, but do not conform with results sadr moosavi and talebzadeh found in their research in 2009. results obtained from the model of rank-size rule somewhat agree with those of a study gharakhanloo et al. conducted in 2008 on the urban network of ardabil. they found that the value of q, despite being less than one and moving towards values that indicated decentralization in the period from 1988 to 1996, suddenly increased in the period from 2006 to 2011, exceeded one, and was moving towards centralization in ardabil province.results obtained from the model of the limit of class differences are in agreement with those tavakkolinia and shali obtained in their study on urban systems in west azarbaijan province in 2011. they found that there were great statistical discords in population distributions in the cities of the province, and that a clear disharmony and disequilibrium existed in urban population distribution in the province. conclusionurban hierarchy in lorestan province has experienced great fluctuations with respect to spatial distributions in the cities during the periods studied, and population distribution shows great variations in these periods, one of the main reasons of which is the appearance of newly founded cities during the period from 2006 to 2011. during the period from 1986 to 2006, there were 10 cities in the province, but in 2006, this number suddenly rose to 23 and reached 25 in 2011. in other words, during the span of a single decade, more than 13 cities were added to those already existing in the province. many of these new cities were created following incorrect political and administrative decisions and because of the changes made in the municipal law. these new cities still possessed rural characteristics as far as economic, service provision, and cultural and social aspects were concerned, and no infrastructure had been built to cater for the needs of these new cities. in 2006, there were 12 cities with populations less than 5000, and their number rose to 13 in the year 2011, i.e., more than 50 percent of the cities of the province had populations less than 5000. this in itself confirms the sudden increase in the populations of major cities: a city like khorramabad with a population of more than 300000 indicates there are great differences among the cities of the province with respect to their populations. in general, given the issues raised, and taking the obtained results from the models into consideration, it is quite clear that the urban network system of lorestan province almost, and to some extent, preserved an equilibrium state with respect to spatial distribution of cities in the period from 1986 to 1996. however, after the period from 2006 to 2011 and following the creation of new cities, this equilibrium was replaced by a state of disharmony and disequilibrium. to prevent the further worsening of this situation, it is proposed that the following steps be taken 1. filling the gaps, particularly the economic and service provision gaps between the larger cities of the province and the smaller ones, and planning balanced regional programs with the purpose of creating the possibility of equal growth in the cities of the province.2. creating balance and harmony in the spatial organization of lorestan province through building appropriate transportation and service provision systems in deprived regions which have low populations.3. preventing irregular migration from villages and small cities to khorramabad by creating the necessary facilities and providing the required services in these villages and small cities.4. developing and enhancing small-scale local industries and handicraft in villages and small cities with the purposes of strengthening their economy and of preventing migration of people who live in them.key words: urban hierarchy, spatial distribution, entropy model, rank-size, lorestan province