Recent Publications
Publications Archive
Dietzel, C.,Oguz, H., Hemphill, J.J., Clarke, K. C. and Gazulis, N. (2005) "Diffusion and coalescence of the Houston Metropolitan Area: evidence supporting a new urban theory", Environment and Planning-B, Planning and Design, vol. 32, no. 2, pp. 231-236.
Abstract
This research builds on a recent development in urban geographic theory,providing evidence of an oscillatory behavior in spatio-temporal patterns of urban growth.Remotely sensed data on the historical extent of urban areas were used in a spatial metrics analysis of the Houston (USA)metropolitan region. Regularities in the spatio-temporal pattern of urban growth were detected with temporal periods as short as thirty years using spatial metric values,including mean nearest neighbor distance,mean patch area,total number of urban patches,and mean patch fractal dimension.Through changes in these values,a general temporal oscillation between phases of diffusion and coalescence in urban growth was revealed.The results suggest that the hypothesized process of diffusion and coalescence may exist in shorter time periods than previously thought,and that the patterns are readily observable in real-world systems.
Herold, M., Couclelis, H. and K. C. Clarke (2005) "The role of spatial metrics in the analysis and modeling of urban land use change", Computers, Environment and Urban Systems, 29, 369-339.
Abstract
The paper explores a framework combining remote sensing and spatial metrics aimed at improving the analysis and modeling of urban growth and land use change.While remote sensing data have been used in urban modeling and analysis for some time,the proposed combination of remote sensing and spatial metrics for that purpose is quite novel.Starting with a review of recent developments in each of these elds,we show how the systematic, combined use of these tools can contribute an important new level of information to urban modeling and urban analysis in general.We claim that the proposed approach leads to an improved understanding and representation of urban dynamics and helps to develop alter- native conceptions of urban spatial structure and change.The theoretical argument is then illustrated with actual examples from the urban area of Santa Barbara,California.Some questions for future research are nally put forward to help strengthen the potential of the proposed framework,especially regarding the further exploration of urban dynamics at dif- ferent geographic scales.
Syphard, A. D., Clarke, K. C. and Franklin, J. (2005) "Using a cellular automaton model to forecast the effects of urban growth on habitat pattern in southern California," Ecological Complexity, vol. 2, pp. 185-203.
Abstract
Land use change is one of the most important anthropogenic factors affecting terrestrial ecosystems, causing habitat loss, fragmentation, and interactions with other components of global change, such as biological invasions of non-native species. In southern California, population growth and economic expansion are the primary drivers of land use change, and the population is expected to double in 40 years. Although directly adjacent to the region s largest metropolitan area, the Santa Monica Mountains National Recreation Area (SMMNRA) remains mostly undeveloped, with 50% of the area protected as parkland. In this study, a cellular automaton (CA) model was calibrated using historical growth patterns in the region, and used to forecast three scenarios of urban growth in the SMMNRA from 2000 to 2050, with development prohibited on slopes greater than 25%, 30%, and 60% slope. Habitat pattern and extent under these scenarios was assessed using several landscape metrics, then compared to results from a GIS overlay model developed for the same region. The CA model predicted urbanization to increase from 11% of the landscape in 2000 to 26%, 35%, and 47% in 2050, respectively, for the three slope scenarios. In 2000, the majority of vegetation constituted one large, interconnected patch. With development prohibited beyond 25% and 30% slope, this patch will become, by 2050, increasingly perforated, but should stay relatively intact. However, if growth is permitted up to 60% slope, the patch breaks apart, resulting in a shift in spatial pattern dynamics on the landscape (as reflected by other landscape metrics). General growth patterns predicted by the GIS overlay model resembled those generated by the CA, but the CA model produced more patches and edge in the landscape. Because it is temporally explicit, the CA model was able to capture non-linear, emergent behavior and a phase transition in the type of growth occurring in the landscape that was not apparent in the GIS overlay predictions.
Silva, E. and K. C. Clarke (2005) Complexity, emergence and cellular urban models: lessons learned from applying SLEUTH to two Portuguese metropolitan areas. European Planning Studies, January 2005, vol. 13, no. 1, pp. 93-115 (23).
Abstract
We explore the simulation of urban growth using complex systems theory and cellular automata (CA). The SLEUTH urban CA model was applied to two different metropolitan areas in Portugal, with the purposes of allowing a comparative analysis, of using the past to understand the dynamics of the regions under study, and of learning how to adapt the model to local characteristics in the simulation of future scenarios. Analysis of the two case studies show the importance of SLEUTH s self-modification rules in creating emergent urban forms. This behavior can help build an understanding of urban social systems through this class of CA.
Dietzel, C, Herold, M., Hemphill, J.J., and Clarke, K.C. (2005). "Spatio-temporal dynamics in California's Central Valley: Empirical links to urban theory", International Journal of Geographic Information Science, 19, 2, pp. 175-195.
Abstract
This paper explores an addition to theory in urban geography pertaining to spatio-temporal dynamics. Remotely sensed data on the historical extent of urban areas were used in a spatial metrics analysis of geographical form of towns and cities in the Central Valley of California (USA). Regularities in the spatio-temporal pattern of urban growth were detected and characterized over a hundred year period. To test hypotheses about variation over geographical scale, multiple spatial extents were used in examining a set of spatial metric values including an index of contagion, the mean nearest neighbor distance, urban patch density and edge density. Through changes in these values a general temporal oscillation between phases of diffusion and coalescence in urban growth was revealed. Analysis of historical datasets revealed preliminary evidence supporting an addition to the theory of urban growth dynamics, one alluded to in some previous research, but not well developed. The empirical results and findings provide a lead for future research into the dynamics of urban growth and further development of existing urban theory.
Tobler, Waldo (2005). Using asymmetry to estimate potential. Solstice (An Electronic Journal of Geography and Mathematics), 14(2)
Abstract
Network analysis is often based on matrices of connections. Any asymmetric square array of this type can be decomposed into two components. The anti-symmetric part is especially interesting because this can be used to view influence patterns. A journal to journal table is examined as an example. Another application is to the geographic migration of people.
