Introduction

The rapid growth of cities, which arose due to the increase in their population, has created many problems, especially in the cities of developing and less developed countries, among these problems are the changes in the spatial structure of cities due to the change in the social structure, the change in the economic and physical structure of the cities. . The result of these changes is the increase of unprincipled and unregulated constructions in cities, and along with the failure to properly implement urban development plans, it is one of the most important issues that has involved urban planners and city affairs trustees (Rafiian et al., 2013, 25). Urban construction control requires logical planning and management and rewriting the planning and management method by local governments (Zeyang Li et al, 2020: 5).
Materials and methods
The current research is applied in terms of purpose and descriptive-analytical in terms of nature and method. According to the nature of the study, the method of collecting information is in the form of documents and a library, which includes the investigation of the spatial development pattern of Yasouj city since 1345-95. Spatial development of Yasouj city was analyzed temporally and spatially using spatial analysis techniques in ArcGIS software environment. Then, using Shannon's entropy model and Heldren's model, the city structure and urban growth have been analyzed.
Results and discussion
During the period of 1355 to 1365, for the first time in the history of its formation, the city of Yasouj experiences significant growth and development, and the area of the city reaches 86 hectares. In the period from 1365 to 1375, the population of Yasuj city will increase 74 times, of which 79% are immigrants; The migration of villagers to the city and the integration of villages into the city is one of the main factors of the city's development during this period. The area of Yasouj city increased to 1801 hectares between 1375 and 1385 and experienced a great growth compared to previous periods (Table 1). During the period of 2015 to 2015, the city of Yasuj grows to some extent in terms of urban services and facilities, and a huge wave of villagers and residents of neighboring cities immigrate to Yasuj to benefit from these services and facilities, and they cause the development and expansion of the city more than ever before; Due to topographical limitations, the expansion of the city in this period is very little to the north and more to the east and west and to some extent to the south .
Conclusion
The results of the present research show that during the period from 1343 to 1395, the population of Yasouj city has increased from 34 people in 1343 to 134,532 thousand people in 1395, the area of the city has increased from 5 hectares to 40 thousand hectares, and the gross density of the city has increased from 186 people to 60 people, and the physical development of the city has increased from Since its inception, until now, in the two axes of Yasuj-Siskhet and the northern side of the city, due to topographical limitations, high slope and forest cover, expansion is limited. In other words, agricultural lands have been lost as a result of the direct impact (that is, the construction of agricultural lands as a result of the physical development of the city) or the indirect impact (the non-use of agricultural lands due to land speculation and their addition to the city limits) of urban development. Among the reasons for the increase in the population of Yasuj city over the past 50 years are: natural population growth, the centrality of the province, the settlement of nomads, the expansion of the physical boundaries of the city and the annexation of villages leading to the city, migrations, both urban and rural migrations as a result of land reforms, imposed war, weather suitable etc.; So that the city of Yasouj has grown a lot in terms of physical and population since its inception until today. The results of this research show that every year a large part of first, second and third grade agricultural lands are built, and the development without a plan and without regard to environmental considerations causes the destruction of the ecosystem and consequently the destruction of the landscape, natural resources and high-quality agricultural lands and increases the cost of transporting equipment. And it becomes an urban facility. Considering that the longitudinal linear development of Yasuj city on the two axes of Yasuj-Shiraz and Yasuj-Sisakht, in addition to destroying land suitable for agriculture, increases the cost of transferring urban equipment and facilities, it is suggested to prioritize internal development and high-rise development of the city. The current research is applied in terms of purpose and descriptive-analytical in terms of nature and method. According to the nature of the study, the method of collecting information is in the form of documents and a library, which includes the investigation of the spatial development pattern of Yasouj city since 1345-95. Spatial development of Yasouj city was analyzed temporally and spatially using spatial analysis techniques in ArcGIS software environment. Then, using Shannon's entropy model and Heldren's model, the city structure and urban growth have been analyzed. The current research is applied in terms of purpose and descriptive-analytical in terms of nature and method. According to the nature of the study, the method of collecting information is in the form of documents and a library, which includes the investigation of the spatial development pattern of Yasouj city since 1345-95. Spatial development of Yasouj city was analyzed temporally and spatially using spatial analysis techniques in ArcGIS software environment. Then, using Shannon's entropy model and Heldren's model, the city structure and urban growth have been tical in terms of nature and method. According to the nature of the study, the method of collecting information is in the form of documents and a library, which includes the investigation .documents and a library, which includes the investigation of the spatial development pattern of Yasouj city since 1345-95. Spatial development of Yasouj city was analyzed temporally and spatially using spatial analysis techniques in ArcGIS software environment. Then, using Shannon's entropy model and Heldren's model, the city structure and urban growth have been tical in terms of nature and method. According to the nature of the study, the method of collecting information is in the form of documents and a library, which includes the investigation .