Dispersion Pattern Analysis in Troglodytic of Isfahan Province by using the Geographic Information System (GIS)

Abstract
Troglodytic, as structures that are made without the use of usual materials and just by digging the ground or rock and mountain, are important in terms of issues such as adaptation to climate and environment and the optimal use of energy. Isfahan province, as a vast province with an area of about 106786 square kilometers and with different climates, has many examples of troglodytic architecture. This research was based on descriptive-analytical method and its aim was to study the distribution of 19 cases in Isfahan province and discover possible patterns and correlations between their locations and various cultural and natural environments factors. This study sought to answer these questions: 1) How is the dispersion pattern troglodytic of Isfahan province, relative to elevation, distance from water resources including seasonal and permanent rivers and Qanat, slope, distance from roads, location relative to villages and cities and climate and temperature? 2) If these troglodytic are correlated with the mentioned factors, what is the reason of this correlation? And 3) is it possible to determine the use of these troglodytic according to the results of this research? The method was includes collecting information through articles and reports related to archaeological surveys and excavations, gathering spatial and geographical information of the studied troglodytic such as geographical coordinates by field method and finally analyzing the obtained information and classifying them by ArcGIS software. In order to achieve more accurate results, the troglodytic were divided into two categories based on function: residential troglodytic and defensive and ritual troglodytic. Based on findings, it was found that those troglodytic had residential use or generaly were used daily, are more correlated with environmental and geographical factors. On the other hand, the second category of troglodytic, which were built with the aim of hiding, are more related to cultural and human factors. It can be said that in the dispersion pattern of residential troglodytic, environmental factors and in the dispersion pattern of defense and ritual troglodytic, cultural factors have priority.
Keywords: Isfahan Province, Troglodytic Architecture, Dispersion Pattern, GIS, Function.
 
Introduction
Troglodytic architecture, as a special type of architecture, has been created in line with the adaptation of human to the environment. Iran has a diverse dispersion and classification in the field of troglodytic architecture. Isfahan province has many types of troglodytic. Despite the existence of numerous cases of troglodytic structures in Iran, this type of architecture has been less interested by researchers than conventional architecture. In spite of numerous cases of troglodytic structures in Iran, this type of architecture has been less interested by researchers than conventional architecture. Isfahan province contains a lot of types of troglodytic, but the number of identified and studied ones are not many. In these studies the researchers introduced the spaces, described the cultural materials obtained, presented a time frame as the period in which the troglodytic were used, and explained their possible functions. In archaeology, the study of the landscape and the dispersion of the studied areas in relation to the environment has always been important. This kind of research is done with the help of software related to geographic information system (GIS). Many researches have been carried out up to now in the field of using GIS, in order to study the settlement pattern and dispersion of ancient sites and how they are related to different geographical and cultural factors. But the troglodytic have rarely been examined from this point of view. This research has studied the dispersion pattern of 19 cases of troglodytic in Isfahan province in relation to various cultural and natural environments factors by ArcGIS software. The questions and theories raised in line with this research are as follows 1) How is the dispersion pattern troglodytic of Isfahan province, relative to elevation, distance from water resources including seasonal and permanent rivers and Qanat, slope, distance from roads, location relative to villages and cities and climate and temperature? 2) If these troglodytic are correlated with the mentioned factors, what is the reason of this correlation? And 3) is it possible to determine the use of these troglodytic according to the results of this research? The theories raised in relation to the mentioned questions are as follows: 1) the dispersion pattern of troglodytic in Isfahan province is related to both natural environment factors and cultural factors. 2)  Those troglodytic which dating coincided with the Mongol invasion of Iran were used as shelters.
 
Identified Traces
1The factors that have been investigated in this research to analyze the dispersion pattern troglodytic of Isfahan province, among the most important factors are geographical, natural and cultural factors that humans have always considered to choose the right place for various purposes. The result of position analysis of troglodytic, based on these factors, is as follows: 1) Elevation: With increasing elevation, the number of residential troglodytic has increased, and the number of defensive and ritual troglodytic has decreased. 2) Slope: Both types of troglodytic have an inverse relationship with the slope, and the number of troglodytic decreases with the increase of the slope. 3) Distance from permanent rivers: 40% of residential troglodytic are located less than 500 meters from permanent rivers. This study does not show a specific pattern about defensive and ritual troglodytic. 4) Distance from roads: 20% of residential troglodytic and 30% of defensive and ritual troglodytic are less than 500 meters away from main roads. For distances more than 1000 meters, no meaningful relationship can be seen in the case of residential troglodytic. But in the case of defensive and ritual troglodytic, the number of troglodytic has decreased with the increase in the distance from the roads. 5) Distance from Qanat: In both groups of troglodytic, the number of troglodytic decreased as the distance from the Qanat increased. 6) Distance from cities and villages: All studied troglodytic are closely related to villages or cities and are completely dependent on them. 7) Temperature: Almost all the study troglodytic were located in areas that have very hot summers or very cold winters. 40% of residential troglodytic and about 70% of defensive and ritual troglodytic were formed in areas where the maximum temperature is more than 40 degrees Celsius.
 
Conclusion
Based on findings, the dispersion pattern of a number of troglodytic in Isfahan province is related to the factors of the natural and cultural environment. The troglodytic that their function were residential or generally for daily use are more correlated with the factors of the natural and geographical environment. The defensive and ritual troglodytic are mostly related to cultural and human factors and in their construction, factors such as access to roads, hidden entrances, lack of easy access to spaces, staying hidden and safe from dangers have been given more priority than environmental factors. The reason for this correlation for residential troglodytic is adaptation to the environment and harsh climatic conditions. For defensive and ritual troglodytic that are more related to cultural factors, the reason for this correlation was access to a suitable place to hide in order to staying safe from the dangers and attacks of enemies or performing some secret rituals. Although both groups of troglodytic are related to a factor such as temperature but by examining other factors we can see that environmental and geographical factors have priority in the dispersion pattern of residential troglodytic and cultural factors have priority in the dispersion pattern of defensive and ritual troglodytic.