Analyzing the Impact of Physical Changes on the Spatial Structure of the Historical District in Urmia City by Space Syntax and Gis

There has not been enough attention to the structure and shape of the historic core in many ancient cities of Iran. This has led to problems such as inability to adapt to new physical changes, lack of appropriate link with existing structural network and spatial isolation. The main structure of a city is a set of interrelated and continuous urban spaces that encompasses the essential elements and main activities of the city. Understanding of this structure requires a thorough analysis of all aspects of ours. Among the theories that deal with the urban spatial structure, is the space Syntax theory. In the past decades, Urmia city has seen major changes in its structure and its traditional structure and also the historic core of this city like many other cities. Under the influence of hasty actions, has undergone numerous difficulties. This paper with the aims to identify and analyze the process of growth and the urban development of Urmia and its structure, and also the study of the effect of contemporary physical changes on the spatial structure of the city’s historical district and analysis the network access structure and the relationship between key elements of the historical structure of this tissue for investigating the spatial coherence, Using Space Syntax theory, will analyze the structure and spatial configuration of it according to selected parameters for analyzing the urban structure during various periods and also it aims to study the changes of values and the performance of historical texture through the introduction and the study of the analysis elements of urban spatial structure and the output spatial parameters of this theory. The method used in this paper is descriptive, quantitative and a comparative method. In this paper after the presented case study (Urmia city and its historical district) with the Space Syntax method and also with applying the concepts of space syntax parameters and using AutoCAD, Depth map and ArcGIS software the structural analysis has been conducted. In order to study the spatial structural changes of Urmia city and its impact on the spatial structure of the historic core of the town, based on available documents and maps, four main periods of physical evolution of the city that is the years (1933, 1976, 1994, 2016) have been considered for analyzing its structure and entering to the software of space syntax theory. After analyzing of the parameters and analytical maps of the space syntax and the comparison of the periods, validity changes have been analyzed as the most important concepts in this method to study four factors of coherence and coordination of the structure of the historical district, assessment of value and importance of historical orders and its main elements and the manner of distributing of activities in the range. After the analyzing of the findings of the maps and output of the spatial parameters every four year, we have analyzed the criteria for the study of urban space structure and the parameters of the space syntax of city. The spacing variable and the amount of its deviation has been considered as a criterion in the spatial coherence. For the analyzing of the spatial dispersion and city structure consistency and historical range. It can be seen that the lowest deviation and the highest amount of affiliation and thus the highest urban coherence is related to 1933. That this amount after the physical changes of the city has been reduced until 2016 and also city structural integrity has been reduced too. The values obtained from the analysis of value of the city affiliation and historical range during four indicate that the average of the historical context of city is less than the average of the value of city affiliation in four periods during 1933 to 2016. This shows that the internal structure of this area has not been related to this axes. For analysis of the subsequent criterion, the changes in the value of the inter connection of the main historical orders have been studied for structural analysis of the main axes.According to the result from 1933 to 2016 with imposing structure of the accesses of city structure. The spatial physical value of the axis is degraded to inferior position, because both the average value of the interconnection of each axes and also the average difference between each axeses with the total average gradually declined compared to previous periods. In the subsequent analysis public spaces and the main activity centers which contain historical market and the main fields of the historical core (The Velayat-faqih and Ayalat square) and the central mosque of the city has been considered and analyzed as the main religious element in the texture structure. Integration ranges show until 2016, the extent of the interconnection of the main historical spaces, which are one of the major city activity centers and formed down town has been reduced. The next criterion examines the over laps of the most integration axes with the active and attractive users of cities and their relationship. According to the results of this paper it became clear that the performance and historical coherence of the range and its relation to the structure of whole city under the influence of physical changes has been reduced over the time and the internal structure of this range could not be grafted with the overall structure of city. Also a large part of identity values and physical texture affected by these changes have been lost and spatial continuity of main elements and the functional significance of historical orders has been weakened, and this indicates that the rapid physical changes in the recent years had negative effects on the spatial structure of historical range of Urmia city.