Analysis of the effect of urban climate change on the spatial distribution of the population with emphasis on thermal islands Case study of Sari city

With the beginning of the Industrial Revolution in 1830 and the growing growth of human knowledge, various changes have taken place in human life and human needs for energy and consumption of fossil fuels such as coal, oil and natural gas have led to a sharp increase in materials such as Carbon dioxide has been released into the atmosphere. Increasing its population exacerbates this phenomenon. All of these changes have caused the weather to change. The phenomenon of climate change, which is mainly related to the increase of greenhouse gases in the atmosphere, is a clear example in this field. This phenomenon causes many current problems such as gradual warming of the climate, melting of ice, rising sea levels, torrential rains, increasing drought, acid rain and threats to human health. And wildlife species in different regions of the earth (Atabi et al., 2007: 146). The development of urbanization and migration of rural residents to cities to enjoy the benefits of civilization, especially in the second half of the twentieth century led to the overdevelopment of cities (Alijani et al., 2010: 541). The desirability and quality of urban areas make a difference in the value of land use. Knowledge of how urban temperature patterns are distributed allows planners to manage the construction of urban green space to adjust the temperature. Also, by studying the relationship between user patterns and the distribution of thermal patterns, it is possible to provide programs to change and relocate these uses to improve environmental conditions. Despite the year-on-year changes in the average temperature due to the natural variability of the climate, increasing trends in the average annual temperature are evident in most parts of Iran, including the city of Sari. These increasing trends are mainly due to the increase of greenhouse gases in the atmosphere (due to the burning of fossil fuels and changes in the surface characteristics of urban areas (Alizadeh Chobari et al., 2016: 571 and 572). In this regard, the city Sari is located in a dense area of ​​activity and residential centers and with its various capabilities has been able to enjoy a special position in the province.This city due to its strategic location and suitable climate and location ‌ Tourism and unique agricultural capabilities are facing population growth and increased migration. Considering the challenges such as the increasing growth of the urban population, the uneven expansion of cities, the destruction of the environment, etc., which has reduced the quality of life and created heterogeneous uses in different urban areas; As a result, the climatic parameters of the region are also subject to change. In this regard, the effect of these changes on the city of Sari and solutions to deal with it have been studied.

The present research is applied-developmental for the purpose and is descriptive-analytical according to the method of work. In this study, in order to measure the spatial distribution of population in the eleven districts of Sari, data under the Geographic Information System (GIS) has been used. In order to investigate the spatial distribution of population in each area of ​​Sari, the Shannon relative entropy model has been used and to calculate the maximum thermal island intensity, the Oke numerical-theoretical equation has been used. Sari, the capital of Mazandaran province in northern Iran, is one of the largest and most populous cities in Mazandaran province and the north of the country, which is located at 53 degrees and 37 minutes east longitude and 34 degrees and 36 minutes north latitude. In terms of natural location, this city is located in the south of the Caspian Sea and in the plains of Sari city and only its southern and southwestern parts lead to mountains and low satellite hills. The height of the city from the sea level is 18.5 meters and the difference in its area to the coast of the Caspian Sea is 24 kilometers. The general slope of the city is from south to north and is very gentle (Sari Master Plan Studies, Mazand Tarh Consulting Engineers, 2015).

In the present study, the relationship between the spatial distribution of the population and the creation of thermal islands in the city of Sari has been investigated. After examining the spatial distribution of population and the intensity of changes in thermal islands, it is concluded that there is a relative relationship between the two indicators of spatial distribution of population and the intensity of changes in thermal islands in Sari. In region 2 of region 3 of Sari city, which had the lowest equilibrium in the spatial distribution of population, the intensity of changes in thermal islands was also low, and in areas where the spatial distribution of population was semi-balanced (region one of region one, regions 1 and 2 from region 2, and region 1 from region 3 of Sari city), the intensity of thermal island changes was low. Also, in the areas where the spatial distribution of the population was balanced (areas 2, 3 and 4 of area one, areas 3 and 4 of area 2 and area one of area 4), the intensity of thermal island changes was low and moderate. The results indicate the fact that there is a direct relationship between net residential density and the intensity of changes in thermal islands in the city of Sari. As the net residential density increases, the intensity of changes in thermal islands in Sari city increases, and as the net residential density decreases, the intensity of thermal island changes decreases. Based on the findings of the survey of Sari city areas and analysis of the spatial distribution of population and the maximum intensity of thermal island changes, it is concluded that there is a relative relationship between these two indicators in Sari city areas. In the areas that had the lowest equilibrium in the spatial distribution of the population, more intensity changes were observed in the thermal islands and in the areas where the spatial distribution of the population was semi-balanced and balanced, the intensity of changes was less in the heat islands. On the other hand, according to the results of Spearman correlation coefficient, it can be said that the most important effective factor in the maximum intensity of thermal island changes, which is inversely related to this phenomenon, is the net residential density. Areas in Sari that have the highest intensity of thermal island changes They also had the lowest net residential density. Therefore, it is necessary to apply appropriate policies such as revising and improving management in the way of population loading in various urban development plans and planning for the management and organization of urban structures in relation to the intensity of changes in thermal islands. ‌ Can be effective. It can also provide favorable grounds for guiding the development of population policies in various urban development plans to create a balance with sustainability in the city of Sari.