Geographical flows: a fresh perspective on quantifying urban function

Abstract

Urban function refers to various roles and activities that take place in an urban region or a public facility. Previous research only focused on the types of urban function and its quantitative characterization did not attract enough attention. In this paper, we highlight the issue of quantifying the urban function and divide it into two aspects: one is the intensity of the urban function, which can be seen as the capacity to accommodate people engaging in activities related to the function, and the other is its influence on the surrounding area. Due to the cause-and-effect dynamics between urban functions and geographical flows, which refer to the human or objects moving between locations, geographical flows have been used to estimate the intensity and influence of urban function. Based on the review of recent updates, this paper provides a research framework for utilizing flow data to quantify urban function in terms of intensity and influence. Regarding the intensity, the indices are mainly based on the volume of inflow/outflow and their ratio. Regarding the influence, there are two types of indices for evaluating it: one for planar facilities and the other for linear facilities. To describe the intensity and influence of the urban function simultaneously, the volume along with the length of flows are considered into the indices, which can quantify the importance or irreplaceability of a place or facility. The analysis shows that the geographical flows provide a new perspective for quantifying urban function in terms of intensity and influence.