Urban sprawl is an expansion of urban areas characterized by the built up areas increase as the result of non-urban land conversion into urban land. It happens because of the population growth and the development of urban activities that are not balanced with the land supply in the city. Therefore, the evolving urban activities have to use the surrounding areas of the urban which called by suburban areas. The suburban land development is affected by the behavior and decision making by developers who have preferences in location or site selection. The tendency of developers in selecting the location may influence the development patterns, which potentially causes some discontinuous and less efficient development, causing some negative impacts on the environmental balance.
As in around Surakarta City as the core city, it directly borders and has strong linkage with its hinterland areas e.g. Sukoharjo Regency and Boyolali Regency. The urban expansion that occurred in those two regencies along with the development of the city causes some urban sprawl symptoms. A study identified the prediction of urban sprawl direction around the Surakarta City by formulating the mathematic and spatial model of residential location choice based on the developers’ preferences. The developers’ preferences in location choice which were elaborated into variables to be assessed in the study consisted of land price, market demand, regional/city center, conformity with the land use planning, land availability, proximity to main road, proximity to the core city (Surakarta City) center, proximity to the green open space, and disaster vulnerability.
The study applied mixed methods, i.e. quantitative and qualitative methods. The quantitative method used was based on GIS spatial analysis method to analyze the condition of the variables that affect the location choice (mentioned above), score all of the variables or layers, and determine the location alternatives; whereas the qualitative method used was the analysis method by Analytic Hierarchy Process (AHP) to make ranking and weighting of the variables. The results of the scores and weights from this analysis were used to formulate the mathematic and spatial model of residential location choice; which was used to predict the urban sprawl direction in Sukoharjo Regency and Boyolali Regency thereafter.
The residential location choice model for Sukoharjo Regency and Boyolali Regency formed had high levels of accuracy. The accuracy percentages of the model for Sukoharjo Regency and Boyolali Regency are 91,39% and 97,02%, respectively.
After using the models for predicting the urban sprawl direction in each regencies, it was concluded that the prediction of urban sprawl direction will have mostly been towards the southern of Surakarta City (in the north side of the administrative area of Sukoharjo Regency) with the concentric patterns at some location near the city and leap frog patterns at some distant points from the city. The urban sprawl pattern to the west side of the Surakarta City will have tended to be concentric (in the administrative area of Sukoharjo Regency) and linear along the street corridor (in the administrative area of Boyolali Regency). Then, there will have only been few alternatives of sprawl potential areas far from the Surakarta City. By identifying the prediction of urban sprawl direction with the models, the development can be controlled through some various instruments and policies in accordance with the factors and variables that affect the market location choice.