Evaluation of the Physical Development Trend of Urban Spaces Located in Mountainous Areas in Relation to Environmental Hazards (Case Study: Ilam City)

Natural hazards are among the challenges facing many cities, including Ilam. The location of the city of Iran in the Zagros belt and leading to the mountain unit has caused this city to have a high vulnerability potential against natural hazards such as earthquakes and landslides. Due to the importance of the topic, in this research, the physical development process of Ilam city towards hazardous areas has been evaluated in recent years. In this research, Landsat satellite images, SRTM 30 meters high digital model, the layer related to the epicenter of the earthquakes and other layers of information are used as the most important research data. The most important research tools are ArcGIS, TerrSet and ENVI. In this research, the vulnerable areas against earthquake and landslide hazards have been identified first, and then the development process of the residential areas of this city towards vulnerable areas during the years 1992 to 2022 has been evaluated. Based on the results, a large part of the urban area of Ilam, including its northern and eastern regions, are exposed to the dangers of earthquakes and landslides. Also, the results of this research have shown that the city of Ilam in 1992 had an area of about 7.3 square kilometers, of which about 5.6 square kilometers were in the high risk of vulnerability class. Also, in 2022, it had an area of about 17.8 square kilometers, of which about 11.5 square kilometers was in the high risk of vulnerability category. According to the obtained results, during the recent years, a large part of the constructions of Ilam city have been done in areas with high risk of dangerousness.
 
Extended Abstract
 
Introduction
One of the most important challenges for the progress of societies, especially urban areas, has been the increase in the risk process. Hazards can be of natural or human origin, and different regions have different potentials for the occurrence of various hazards according to their geographical location and political, economic and social conditions. Due to the importance of the subject, today many scientists and urban planners pay attention to the monitoring of environmental changes in urban areas. According to its geographical location, Iran has a high potential in the field of hazards, especially natural hazards. Every year, natural hazards in Iran cause a lot of human and financial losses, which is very effective in slowing down the country's development process. Different regions of Iran, especially its urban areas, have different potentials in the field of various risks, and it is necessary to pay special attention to this important issue in different programs, especially construction planning. Ilam city is one of the areas exposed to natural hazards. The location of the city of Ilam in the Zagros belt and leading to the mountain unit has caused this city to have a high vulnerability potential against natural hazards such as earthquakes and landslides. Considering that the dangers of earthquakes and landslides are always associated with many human and financial losses, therefore, in this research, the physical development process of Ilam city towards the hazardous areas during recent years has been evaluated.
 
Methodology
This research is based on descriptive-analytical and quantitative methods. In this research, Landsat satellite images, SRTM 30 meters high digital model, the layer related to the epicenter of the earthquakes and other layers of information are used as the most important research data. The most important research tools are ArcGIS (to prepare the desired maps), TerrSet (To do the OWA model) and ENVI (to prepare the land use map of the region). According to the desired goals, this research has been done in 4 stages. In the first stage, vulnerable areas against earthquakes have been identified. In the second stage, vulnerable areas against landslides have been identified. In the third stage, a map of the region's vulnerability has been prepared, and for this purpose, the high and very high vulnerability potential classes of the studied hazards have been combined, and in this way, a map of the areas exposed to natural hazards has been prepared. In the fourth stage, using Landsat satellite images and through ENVI software, a map of the urban area of Ilam during the years 1992 and 2022 has been prepared. After preparing the map of the residential areas, the distribution of these areas in the areas exposed to earthquake and landslide hazards during the years 1992 and 2022 has been analyzed.
 
Results and Discussion
Due to the fact that the risk of earthquake is always associated with a lot of loss of life and money, it is very important to identify the areas exposed to this risk. The location of Ilam city has caused this city to have a high seismic potential. Based on the results, the northern and eastern regions of Ilam urban area have a higher vulnerability potential against earthquake risk due to the type of lithology, high slope and proximity to the epicenters of earthquakes that occurred in the region. is Also, due to the fact that the city of Ilam is surrounded by mountains, parts of the peripheral areas of this city are at risk of landslides. Due to the importance of the topic, in this section, the vulnerable areas against the risk of landslides have been identified in the urban area and urban outskirts of Ilam, and based on the results, the eastern, northeastern and southeastern parts of Ilam due to Leading to the mountain unit, the high slope and the existence of communication lines have a high potential in terms of the occurrence of landslide hazards.
 
Conclusion
The location of Ilam city has caused this city to have a high risk potential. The results of this research have shown that a large part of the city of Ilam and especially its northern regions have a high vulnerability potential against earthquakes due to the proximity to the earthquake epicenters, the type of lithology and the high slope. Also, the mountainous location of Ilam city has caused the northern and eastern parts of this city to be at risk of landslides. According to the mentioned cases, under the influence of the natural condition of Ilam city, earthquake and landslide hazards are among the most important hazards facing this city. In this research, the development process of the residential areas of Ilam city towards hazardous areas has been evaluated. According to the results, the city of Ilam in 1992 had an area of about 7.3 square kilometers, of which about 5.6 square kilometers was in the high risk of vulnerability category. Also, in 2022, it had an area of about 17.8 square kilometers, of which about 11.5 square kilometers was in the high risk of vulnerability category. According to the results, in recent years, a large part of the constructions in Ilam city have been done in areas with a high risk of dangerousness, which shows that the environmental strength of the region and especially the vulnerability of the region have not been paid attention.