اسپکتروم

City as a living and dynamic entity has always been changing and developing. That is, rapid changes of urban life have brought about different concepts, theories, methods, and those issues related to the cities. One of the significant causes of urban changes is population. It is also one of the key elements of socio-economic development. The exact prediction of the population structure will make a significant ground for future economic development. Accordingly, awareness of the population structure and trend, as well as its dimensions and extent, will be an ensuring tool for effective decision-making and planning for all issues. Therefore, attention to population structure is a must. This study tried to explore the trend of population changes in Ahvaz metropolis. It took into account the components that shape and change the population structure. The purpose was to include human factor in the related issues. For the purpose, the macro population component, including age, gender, population growth, population density, fertility, literacy, migration, etc. were included. The aim of the inclusion was to identify the criteria of the population structure and to explicate the status of these components at the city level, and finally, to predict and provide desirable scenarios for improving the population of the city. This study tried to see: to what extent are the population components effective in changing the population of Ahvaz? and, what are the most significant population scenarios in Ahvaz?

This applied study used a descriptive-analytical method. At the first stage, using Delphi method and based on the opinions of 15 university professors and experts of relevant organizations, the components that explain population changes were identified. In the analysis stage, 11 factors were used as strong factors that influence on population changes in Ahvaz metropolis. Interpretive Structural Modeling (ISM) and MicMac software were used for this purpose. Finally, using Spectrum software, the population was predicted in horizon of 2051.

At first the factors affecting population change in Ahvaz metropolis were identified. Then, these factors were entered into a Structural Self-Interaction Matrix (SSIM). To do this, a questionnaire was designed. This questionnaire asked the respondents to specify the type of pairwise relationships between the factors. SSIM states that the opinions of experts should be obtained through various management techniques such as brainstorming, nominal group, and development of content relationships between variables. Therefore, the self-interaction matrix was formed using four modes of conceptual relationships and was completed by 15 university professors and experts of the subject matter. The data was summarized based on the structural-interpretive modeling method, and the final structural self-interaction matrix was formed. The results showed that seven factors of age structure, gender structure, population growth, fertility, mortality, migration, and life expectancy (with a penetration power of 11) had exerted the greatest impact, and unemployment, active population, and literacy, with a total penetration power of 11, and the population density with a penetration power of 6 exerts the least impact. Regarding the dimensions, the results showed that 7 factors (with a penetration power of 11) cab be considered the main dimensions of population change in Ahvaz. Except for the population density that is in the group of dependent variables, other factors are in the first group; that is, related variables that according to the experts have high penetration power and dependence and exert the greatest impact on population changes of the city. The decreased fertility and emigration were identified as the two main factors in reducing the population growth of Ahvaz. The population growth rate was 4.95 in 1976 and reached 3.34 in 2016. This number was predicted to be 1.82 in the horizon of 2051. Moreover, the fertility rate is below the replacement level. The emigration status of this city that has always had negative over the past decades. The two factors were identified as the two main factors in the sharp decline of the population growth of the city. Several studies have identified the two factors as the main factors in reducing the population growth rate in human settlements.

The results revealed that gender structure, population density, fertility, unemployment, active population, and literacy are among the factor that exert the most influence on population changes. The factors of age structure, population growth, mortality, migration, and life expectancy are among the most affected factors. Moreover, the results of MicMac revealed that all factors except the population density are among the related variables. Finally, the best scenario for population prediction in the horizon of 2051 was the third scenario (reduced fertility). The scenario recorded more than 98% accuracy in population estimation.

Demographic changes in recent decades have led to rapid changes in Iran's urban system and its hierarchy, with one of its consequences being the increase or decrease in the ranking of cities in this system. The present study examines the position of Tabriz metropolis in the urban system of Iran from 1335 to 1395, and by forecasting the population of this metropolis by 2031, it tries to determine the future position of this city in the urban system of Iran. This study is practical in terms of purpose and descriptive-analytical in terms of nature and research method. The data in the present study were obtained through document analysis and field study (questionnaire and interview). Interviews were used to understand the causes of emigration and a questionnaire was used to understand the causes of fertility decline in Tabriz metropolis. The sample sizes for both instruments were determined based on the saturation principle. The exponential model, Spectrum software, and rank mobility index were used to predict the demographic factors, population forecast, and the study of metropolitan rank changes in the urban system, respectively. The obtained results showed that the decrease in fertility rate and migration are the main reasons for the sharp decline in population growth in the metropolis of Tabriz, with the economic reasons being the main reason. In addition, assuming the fertility rates of 1.5, 1.8, and 2.1 in Tabriz, we will see 1.64, 1.69, and 1.74 million increases in the population of the city, respectively, as well as a decrease in the population of minors and a doubling of elderly population over 65 by the year 2031. The results of population forecast show that the position of Tabriz metropolis will be stabilized as the sixth largest city of Iran's urban system by 2031, but its distance from the seventh metropolis (Qom) will be less, which requires special attention and proper management to prevent its rank from falling again.