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Cellular automata (CA) models are increasingly applied for simulating land-use change in urban areas. However, in areas with strongly mixed land uses, like Flanders, different types and intensities of human activity occur within a single dominant land use. This is in conflict with the discrete and dominant land-use states applied in CA. The direct modelling of the intensity of activities (population density and employment in different sectors) within a CA grid environment is an interesting alternative to model mixed and multifunctional land use. In this research, an activity-based cellular automata (ACA) model, developed by White et al. (2012), is further enhanced, applied and calibrated for Flanders. It also uses a variable grid approach: linking with a regional model is not necessary because the neighbourhood is expanded to the entire modelling area. The model should be able to cope with the complex multi-nodal structure and messy morphology of Flanders, typified as it is by multifunctional land use and diffuse, fragmented urban development strung out along roads. This presentation will explain a method we developed to compute and store distances between cells in the variable grid ACA. This calculation should be based on the existing transportation network rather than on simple Euclidian distances applied in classical local CA neighbourhoods, because the distances in the expanded variable grid neighbourhood are much larger than in the original local one. Initially we only used the road network for time computations between cells. For the final model, we are developing different accessibility calculations for different activities, including public transport and waterways. Reference White, R., Uljee, I., and Engelen, G., 2012. Integrated Modelling of Population, Employment, and Land Use Change with a Multiple Activity Based Variable Grid Cellular Automaton, International Journal of Geographical Information Science, 26, 1251-1280. |
