Extended Abstract

Introduction

The industrialization boost in the developing countries since the beginning of the 20th century precipitated an increase in urban production and income, and consequently fueling an increasing demand for municipal services. This industrial increase catalyzed the exponential growth in both the number and physical size of cities. The unregulated physical sprawl of urban areas into their peripheries has created a critical challenge in the spatial development management of cities. The rapid demographic shifts and physical expansion of Urmia necessitate a robust and systematic approach to its development. To this end, determining the optimal spatial orientation for urban physical expansion requires the managers to consider the factors that influence land suitability. Variables such as topographical slope, inherent land capabilities, and proximity to the transportation network must be considered and added to the plans in order to facilitate urban growth and minimize detriment to surrounding agricultural lands. Urmia plays a crucial  administrative, economic, social, and industrial center in the west of Iran and now is experiencing rapid physical growth towards the fertile agricultural lands that embrace this city. Accordingly, a systematic planning paradigm is necessary to ensure that urban physical expansion goes in a way that preserves valuable agricultural lands. Given the integrative, processing, and analytical capabilities of geographic information systems (GIS) and the remarkable role of multi-criteria evaluation (MCE) in evaluating land suitability, these instruments seemed to be necessary for proposing an optimal pattern for the physical development of this city. This research chose Urmia as a case study and tried to spatially analyze the suitability of land for both continuous and discontinuous urban development within a specified peripheral radius around the city. This study tried to delve into the pattern of land suitability of Urmia. 

Method

This applied research employed a descriptive-analytical method. The IDRISI Selva and ArcGIS software were used for the preparation of criterion status maps. The determination of land suitability for continuous and discontinuous urban development was done in the MCE module. The Weighted Linear Combination (WLC) operation was run in the IDRISI Selva. For the standardization of data employed in the multi-criteria analysis process, the standardization method based on the degree of membership in a fuzzy set (fuzzy membership function) was applied. CRITIC method and the pairwise comparison technique were applied for weighting of the data. The results were a map based on the degree of membership in a fuzzy number domain, a standardized map, and a value-assigned map. Here, land status scenarios showing higher desirability were assigned superior scores on the standardized map derived from fuzzy membership.
 

Results

Within Multi-Criteria Evaluation (MCE), the Weighted Linear Combination (WLC) operation was run in the IDRISI Selva. By implementing a summation overlay operation on the standardized and weighted map layers, a composite score or aggregate value was derived for each case that allowed the options to be ranked based on their scores. The option receiving the highest score (rank) is consequently identified as the optimal alternative. On the opposite, an examination of the prioritized land suitability levels revealed that these surfaces exhibit a scattered and fragmented configuration, which may, in certain instances, be deemed controversial with respect to a coherent and systematic urban development pattern. To this end, this study defined and prioritized development units for both continuous and discontinuous urban physical expansion in 1000 \times 1000 meter (one-square-kilometer) dimensions. For this purpose, after converting the raster map into cells of the specified dimensions, the average values resulting from the multi-criteria assessment within each cell were calculated. These values, obtained via the extract function, were assigned to the respective cells using the assign function. This process generated an image of a network of 1000 \times 1000 meter cells. Each cell in this network displayed a specific value, with higher-valued cells indicating a superior degree of suitability for the intended land use.
 

Discussion and Conclusion

The outcome of the operational steps and protocols of implementing the WLC model was a prioritized suitability map of land for urban development. Every pixel of a score closer to 255 signifies the most favorable condition for urban development, which can be considered for either continuous or discontinuous urban development phases. This map serves as a guidance for selecting high-priority parcels in the adjacent to the current urban fabric, as well as for selecting high-priority parcels in the specified radius designated for discontinuous urban expansion. An analysis of the status of the high-priority pixels identified on the land suitability map with respect to each individual criterion used for determining suitability for continuous and discontinuous urban 
development showed the favorable condition of these pixels in the mentioned criteria. The status check of the prioritized pixels showed that their standardized fuzzy scores were above 170 in most criteria. Consequently, these areas can be considered for continuous and discontinuous urban developments.