عنوان مقاله [English]
Urban development planning has always been faced with new challenges of increasing complexities in the decision-making environment which makes it necessary to use new methods for predicting and preparing for the future. In this regard, as a new approach, the planning based on making scenarios will help identify and present different scenarios for making specific decisions in urban management. In the process of urban development, the subdivision of land has always been a controversial topic with regard to new developments.
Complexity and multi-dimensionality of urban development process have made its analysis difficult due to uncertainties and the probability of occurrence of various futures. The planning based on making scenarios is one of the common ways to deal with uncertainty in the environment. Unlike traditional planning methods, this approach develops potentially different views of the future and thus provides a basis for creating solutions and options suitable for different situations. In the planning of urban development, land subdivision is considered as the first stage of design. Investigation and analysis of the effects of different patterns of land subdivision in a vacant lot is an important part of urban development projects. Because of the various economic, social, and physical factors involved in the process of land subdivision, the need to examine their impacts is necessary. In this regard, the purpose of the present study is to apply the factors affecting the subdivision of land plots and the presentation of its various patterns in the process of urban development with the approach of making scenarios. The basic tool used in this regard is the model developed by Dahal and Chow (2014). This model is based on vector space and automatic land division. Based on these properties, different patterns of land subdivision have been presented in different scenarios. A probable scenario has been selected for Semnan city as the case study of the research compatible to the characteristics of the city.
In the present study, four factors of household dimensions, income level, land price, and access to urban centers were selected as independent variables and land area was selected as the dependent variable. This study is an applied research in terms of purpose with a descriptive-analytical method. The proposed modeling for land subdivision in the developed areas of Semnan is based on the comprehensive plan carried out in seven steps:
Step 1: Calculating the amount of land to develop the city in the comprehensive plan in horizon 2026.
Step 2: Determining the blocks in the developed margin area
Step 3: Determining the spatial value of each of margin blocks
Step 4: Providing a regression relation according to the factors affecting the size of the segments of the land
Step 5: Predicting income growth and land price in the comprehensive plan horizon (2026)
Step 6: Providing different scenarios for land division in the comprehensive plan horizon (2026)
Step 7: Conclusion and selection of the probable scenario
Results and discussion
The results of the significance of each independent variable in explaining the dependent variable have been presented in a regression relationship in Semnan city as the study area. According to the predictions of the comprehensive plan horizon (2026), we will need 86 hectares of land. The land subdivision modeling process has been conducted in seven steps. Basic tool was used to divide the land in the model presented by Dahal and Chow (2014) to divide large pieces of land based on size, shape, and direction. In this research, different scenarios have been presented through statistical methods. According to previous studies, accessibility, household dimension, land price, and household income level were selected as the main factors affecting the determination of the area of land segments. The effects of each of the factors were determined based on a regression relation in Semnan city. On the other hand, each identified margin block has a different spatial value based on two factors of accessibility and land price and the households tend to live in one of the margin blocks according to their economic power and suitability. Thus, it was assumed that higher-income households will live in blocks with higher land prices and better accessibility. Assuming that the regression relationship in comprehensive plan horizon (2026) holds the spatial value of each block, four different scenarios were presented for the subdivision of land segments using Dehal and Chow’s model (2014).
Given the variables and relationships presented to determine the size of separation segments, four possible scenarios are obtained and finally, according to the characteristics of the city of Semnan, the probable scenario is based on accommodation of low and medium level of income in margin area of city. It has been selected as the pattern of subdivision. In order to select a scenario which is more consistent with the future conditions of urban development in Semnan, we used the views of real estate agencies (6 real estate agencies) and 4 urban planning experts of Semnan municipality. Real estate agencies were asked to choose the probable scenario according to land price, land sale, mortgage, rent, and area of existing segmented lands in the margin neighborhoods of Semnan such as Rozieh Town, Janbazan Town, 400 Units and Mehr Housing Units. This is conducted according to people’s living standards and their willingness for housing in these neighborhoods. In addition, the urban experts of the municipality were asked to choose the desirable scenarios by considering the population increase in Semnan city by 2026. The variables are dependent upon the immigrant population, land price, the number of licenses issued for construction, the lack of facilities and land uses, and, finally the economic, social, and cultural characteristics of the inhabitants of the margin neighborhoods. By summing up the obtained comments, it seems that the scenario number four is the most likely option from the view of most experts.