SELECTED ASPECTS OF URBAN COMPLEXITY
Leibniz Institute of Ecological Urban and Regional Development, Dresden, Germany
Complexity Science Hub Vienna, Vienna, Austria
As cities represent an emergent phenomenon themselves, they are a prime example of complex systems. Most striking is their regular organization across many scales. Scaling appears in at least three respects, (i) city size distributions, (ii) fractality, and (iii) urban scaling. The discovery of regular city size distributions goes back to Auerbach in the beginning of the 20th century. Today they are best known as Zipf’s law for cities. While empirically well studied, there is no consensus on the processes behind them. Since Mike Batty’s “Fractal Cities” (1994) also fractality of cities became well known. New data permits more detailed and systematic analysis. Urban scaling, i.e. the non-linear scaling of urban indicators with city size, is being studied since the last two decades and is intriguing due to its simplicity and robustness. In this presentation I introduce the three themes and draw connections between them. Best established is the use of fractal concepts in models to explain urban scaling. There is empirical evidence of a relation between city size distributions and urban scaling exponents. The link between city size distributions and fractality is challenged by the fact that they look at very different scales. I conclude with perspectives of an urban complexity research agenda.
