An Analysis of Changes in Network and Urban System of Rasht Town ship in the Last Three Decades

Network and urban system in Rasht town ship suffers from disequilibrium and this trend is constantly increasing due to the city dominance over the surrounding region and even whole province and the lack of strong functional relations among the centers.In such a condition, the deployment pattern of population and activity in town ship does not follow a right exploitation system of capacities and potentials displaying an inappropriate picture of population deployment. Consequently, the urban network of the town ship lacks a hierarchal function, and the spatial distribution and population volume do not follow functionally hierarchal system. The main objective of the present article is to study system and urban network and an evaluation of the changes in order to present balancing strategies to achieve a logical relationship among the current habitats.
Research Methodology Based on the purpose of the study, this article is an applied one. Regarding methodology, however, it is descriptive-analytic. To collect data, documentary and field studies have been carried out. Documentary study is used to describe the conceptual framework of the study and to complete this documentary study, the field method of data collection has been conducted. Then, models of city size distribution and urban hierarchy such as Zipf Model, logarithmic distribution of rank and size, Lorenz Curve, and Gini density coefficient were used to study and analyze the network and urban system of Rasht city.
Presently, Rasht as the first city in the region has over 92 percent of the urban population, and the second, third, fourth, fifth, and sixth cities of Khomam, Lashtnesha, Kochesfahan, Khoshkbijar, and Sangar have respectively allocated around 2.14, 1.8, 1.39, 1.24, and 1.06 percent of the whole population. There is a high gap and distance between these cities and Rasht in terms of number and percent of population. This issue indicates an undesirable condition of population distribution in town ship which imposes an obvious influence over the process of the city development, and the high and low rates of job creation. This is quite evident from frequently daily references of people from surrounding cities and villages to Rasht for working, shopping, etc.
Since past decades, the city of Rasht has continually preserved itself as the shopping center so far as it has enjoyed a very high growth in that while small cities carrying special stand in local and regional urban network, have not enjoyed development process and have finally been forgotten.
The result reached in the logarithmic distribution of rank and size of different regions of Rasht reveals that this coefficient had a negative slope of less than one at the time of study indicating disequilibrium in regression slope in the town ship urban system and the dominance of the city that follows the first urban pattern which is highly increasing. In all periods of population census, Lorenz curve in Rasht town ship has a high dent which can be felt from the separation degree of monotonous distribution line. The distribution of the cities in the region under study, the numerous small towns, and the presence of metropolitan city of Rasht have resulted in low efficiency in communication among surrounding cities.
The result of survey conducted on the hierarchal system of the city through model of Lorenz curve and the Gini density coefficient indicates that population distribution of cities in 1976 and 1996 was half balanced and had critically imbalance condition in 1986 and 2006.