Configuring the neighbourhood effect in irregular cellular automata based models

ABSTRACT

Cellular automata (CA) models have been widely employed to simulate urban growth and land use change. In order to represent urban space more realistically, new approaches to CA models have explored the use of vector data instead of traditional regular grids. However, the use of irregular CA-based models brings new challenges as well as opportunities. The most strongly affected factor when using an irregular space is neighbourhood. Although neighbourhood definition in an irregular environment has been reported in the literature, the question of how to model the neighbourhood effect remains largely unexplored. In order to shed light on this question, this paper proposed the use of spatial metrics to characterise and measure the neighbourhood effect in irregular CA-based models. These metrics, originally developed for raster environments, namely the enrichment factor and the neighbourhood index, were adapted and applied in the irregular space employed by the model. Using the results of these metrics, distance-decay functions were calculated to reproduce the push-and-pull effect between the simulated land uses. The outcomes of a total of 55 simulations (5 sets of different distance functions and 11 different neighbourhood definition distances) were compared with observed changes in the study area during the calibration period. Our results demonstrate that the proposed methodology improves the outcomes of the urban growth simulation model tested and could be applied to other irregular CA-based models.

KEYWORDS:

• Irregular space
• neighbourhood
• cellular automata
• modelling
• simulation

Acknowledgements

This research was performed within the context of SIMURBAN2 project (Geosimulation and environmental planning on metropolitan spatial decision-making. Implementation to intermediate scales) (CSO2012-38158-C02-01), funded by the Spanish Ministry of Economy and Competitiveness. The Universidad de Alcalá supports the first author within the ‘Ayudas para la Formación de Personal Investigador (FPI) 2012’ framework and the ‘Ayudas de Movilidad para el personal Investigador en Formación 2014’ to perform the research at Birkbeck College, University of London. The authors would also like to thank the ‘Servicio de Traducción de la Universidad de Alcalá’ which provided language help and to the anonymous reviewers for their very helpful comments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Spanish Ministry of Economy and Competitiveness.