Identification of the Physical Fabric Potential to Infill Development Applying Decision Making and GIS Models (case study: Ahvaz)

Spatial - physical growth of cities makes many problems such as waste of energy, destruction of environment, an increase of urban infrastructure and service expenses, a change of agriculture land application , air and soil pollution, lack of security for the residents’ demands etc. Some proposed approaches to criticizing these problems are smart growth, growth mangement, new urbanism, campact city and urban infill development. Infill development is trying to utilize vacant lands, rehabilitation and renovation of old textures, redevelopment and applying the unused capacity of lands in the city. The emergence of some problems due to physical-spatial growth of Ahvaz shifts the attention to critical approaches against horizontal distribution. Some of these problems are the low level of quality of life and human development indicators, lack of full enjoyment of Ahvaz residents from residential units, vast old texture in the middle of the city with urgent need for redevelopment and reorganization, concentration of about 40 percent of the city population in unsustainable areas of the city etc. The present study aims at identifying the redevelopment capacities of physical texture of Ahvaz regarding both the effective factors on urban development and prioritizing the identified textures for redevelopment.
Materials and The Research aims at identifying the lands and redevelopment capacities by applying the hybrid decision making models in GIS. As the first step, the exact definition of the problem is provided. Then, according to research goals, at first, the factors and criteria were collected through literature review and interviews with the experts. Since the relationship between the criteria and their effects was different from the goal of the study, two questionnaires called Dematel and ANP were applied. As the first step, Dematel questionnaire was given to the experts and elites. When the relationships among the criteria were determined and drawn based on the Dematel output, the second questionnaire was given to decision makers to calculate the weight and their importance. Generally, when the problem is identified in the spatial multi-criteria analysis, it is necessary to show each criterion in the form of a layer in GIS-based databases. Therefore, the criterion maps were prepared in the environment of ARC GIS software. Moreover, the fuzzy function was applied to standardize the layers in the environment of ARC GIS. The fuzzy function, incremental linear function and other layers are standardized in a way that two different functions are standardized by positive and negative layers. In the final step, using GIS capabilities, MCDM method and VIKOR technique were used to combine the layers and identify lands and redevelopment potential respectively.
The final prioritize map of physical texture is presented in five classes to reach infill development. The first priority with the area 26,646,871.04 m2 includes desolated, industrial, military and sports applications, urban facilities and urban equipment which are dispersed throughout the city. Moreover, except for the fourth priority which is located in the central part of the city, other priorities are dispersed throughout the city; like the first priority.
This research considers the infill development of Ahvaz, for this city is dealing with many problems due to the sprawl problem. From the infill development strategies, the strategy of physical texture redevelopment is chosen as the main research strategy. Infill development has been studied in previous research in different aspect like the physical criteria (materials, building life, building quality etc.), environmental (slope, soil type and erosion), accessibility (access to service, and various necessary infrastructure including water network, sewerage, electricity, gas, etc.) buffer and limitations (river, industrial usage, etc.). In this research, in addition to the aforesaid criteria, education and employment in infill development debate are used. The employment criterion shows the ability of the owner resident to participate in development, while education criterion indicates the people's participation due to their awareness. Redevelopment and infill development consist of different strategies such as incompatible transmission of land application, using the vacant lands, rehabilitation and renovation of old textures and slums, etc. The target redevelopments of this research are the textures and lots having access to service applications, observing the restrictions and buffers, and having high potential level in terms of participation.
The cities of Iran are facing the problems like boundless spread of city, the destruction of agricultural lands and environmental problems due to lack of careful planning about land application which lead to not only inefficient application of the capabilities and available potentials but also improper observation of the population pattern settlement. Weakened physical conditions of the neighborhoods and the dissatisfactions can eventually lead to the loss of neighborhoods, cities and finally whole metropolitan area. In this condition, the urban infill development makes the lands and old buildings ready for re-application, help to the development of the city perspective and life environment, increase the opportunity of buying house, and help to attract and retain the residents with various incomes. Therefore the quality of life in old neighborhoods is enhanced. The present study aims at identifying the infill redevelopment potential of physical texture in Ahvaz. At the end of research, the final map made in the classified physical texture and infill development priorities are presented. Besides, the applications are prioritized based on the priority (according to the pixel value) to infill development. First priority includes desolate, industrial, military, sports and urban infrastructure, and urban equipment.