Exploring the spectrum of urban area key figures using data from Finland and proposing guidelines for delineation of urban areas

Urban area definitions are commonly used worldwide to reflect countries' urban population percentages. The measurements are based on local factors and differ widely across countries, making them non-comparable. This is well acknowledged among specialists; however, they are commonly used in everyday practice as universal measurements, and even compared with each other. The problem is that we do not know the degree of error in such comparisons. For this purpose, in the study presented here we analysed and categorised different European national urban area definitions, testing them in the case of Finland. Definitions from 27 European countries were divided into two main categories according to the end result areal unit of the definition and further into seven subcategories based on the criteria used. Thirteen different definitions in the case of Finland were tested using spatial analyses with GIS. The results indicate that urban population percentage varies widely according to different definitions, making their comparability infeasible. The difference is even greater in the case of urban area ratio and population densities of urban areas between the two main categories. The results prove that definitions based on LAU areas cannot illustrate urban areas and their densities coherently. In light of a literature review on certain relational urban area delineation methods and the case study, desirable characteristics for the delineation of urban areas were highlighted. Consequently, a constant, structured evaluation of urbanity measurements and their underlying logic is necessary to enable unambiguous discourse on urban area in urban sciences. The results could help in formulating the applicability of the concept of urban area in scientific and popular communication and media.

Automated summary

This article discusses the differences and comparability issues of urban area definitions in different countries, and tests the practical effects of different definitions using a case study in Finland. The results show that the definitions have a significant impact on urban population percentages and population densities. Therefore, it is crucial to have accurate methods and criteria for delineating and evaluating urban areas.