تحلیل تاثیر عوامل ژئومورفولوژی در پراکنش سکونتگاه‌های باستانی (مطالعه موردی: شهرستان پیرانشهر)

Introduction
How the first human settlements came to be is an important issue, and from different scientific perspectives, different answers can be given; because the creation or degeneration of these settlements is not the choice of individuals; it depends on countless human and natural conditions. Studies show that the establishment of human societies on the ground has always been done in order to achieve maximum natural resources such as water resources, adequate vegetation and access to arable land, this effort is undoubtedly based on the principles that today It is interpreted as the science of location. At the beginning of human life, natural hazards were unknown to humans until their occurrence. Natural are also safe. Natural disasters are born of natural elements and factors, but human profiteering intervention in nature affects the quantity and quality of many natural disasters. Considering the mentioned cases, environmental factors, especially geomorphology, have played an important role in locating residential areas throughout history. Accordingly, in this study, environmental factors affecting the distribution of ancient settlements in Piranshahr have been investigated.

Materials and methods
In this research, in order to achieve the desired goals, a 30-meter-high digital model, a layer of ancient sites identified in the region (Masoumian, 2021), a 1: 100000 geological map and a 1: 50,000 topographic map of the region have been used. The most important tool used in the research was ArcGIS and also in this research the combined model of fuzzy logic and AHP has been used. This research has generally been done in two stages. In the first stage, after preparing the layer of ancient sites in the region, the location of ancient sites in terms of slope, slope classes, elevation classes, distance classes from the river, lithology units and geomorphological units are analyzed and thus the distribution status of sites Ancient has been analyzed in relation to environmental conditions. In the second stage, in order to identify areas prone to ancient settlements, the results of the previous stage have been used and using the integrated model of AHP fuzzy areas, a map of areas prone to ancient settlements has been prepared.

Discussion and results
In this study, in order to investigate the effects of environmental conditions on the distribution of ancient settlements, first the location of 67 ancient sites in Piranshahr city has been determined. According to the results, a large part of the ancient settlements are located in the slope classes less than 10%, so that 32 ancient sites (equivalent to 47.8% of the identified sites) are located in this class. In terms of slope, a large part of the ancient settlements are located in the northern directions so that 36 ancient sites (38.8% of the identified sites) are located in the northwest to northeast. In terms of height, a large part of the ancient sites are located in the altitude classes of 1250 to 1650, so that in this category there are 56 ancient sites (equivalent to 83.6% of the identified sites). In terms of distance from the river, a large part of the ancient sites are located near the river, with 48 ancient sites (equivalent to 71.6% of the identified sites), located less than 500 meters from the river. They had. Lithologically, a large part of the settlements are located on Quaternary alluvial sediments, so that 37 ancient sites (equivalent to 55.2% of the identified sites) are located in this unit. Also, in terms of geomorphology, a large part of the ancient sites are located in the alluvial plain unit, so that 37 ancient sites (equivalent to 55.2% of the identified sites) are located in this unit.

Conclusion
Environmental conditions have played an important role in the settlement of residential areas in the past and today. Considering that the knowledge of the effective factors in location selection has an important role in various planning, in this study, the effective environmental factors in the establishment of ancient sites in Piranshahr city have been analyzed. Based on the results, the distribution of ancient sites was directly related to environmental conditions, so that the highest density of ancient sites in low-slope areas, low-lying areas, areas near the river, north slope directions, unit Quaternary alluvium as well as unit of alluvial plains. According to the results obtained at this stage, areas prone to the establishment of ancient settlements in Piranshahr city have been identified that based on the results, the middle areas of Piranshahr city due to the conditions, are prone to the development of ancient settlements. The results of this study have shown that environmental conditions in the past have played a major role in the distribution of residential areas and by examining the environmental conditions of each area to a large extent can be found the existence of ancient sites in that area.