Urban Intensities. The Urbanization of the Iberian Mediterranean Coast in the Light of Nighttime Satellite Images of the Earth

Joan Checa,Oriol Nel·Lo

doi:10.3390/urbansci2040115

Abstract

The contribution shares the approach of critical urban studies that have conceptualized urbanization more as a process than as a sum of spatial forms. Thus, the contribution studies the urbanization process not only from the point of view of the physical occupation of land but also considers changes in the intensity of the uses of space. To fulfill this aim, the new sources of nocturnal satellite images are particularly useful. These allow us to observe the intensity of urban uses both in terms of their distribution over space and their recurrence over time. The research focuses on the Iberian Mediterranean coast and permits the verification of the intensity of the urban uses of the space for the whole of this area and their seasonal variations throughout the year. The source of the study are the nighttime satellite images of the Earth for the 2012–2017 period from the NASA SNPP satellite equipped with the VIIRS-DNB instrument. By establishing a threshold of urban light the research shows that those districts with the greatest extensions of urban light do not necessarily correspond with the most densely populated areas. Similarly the absence of urban light does not necessarily indicate the absence of urban uses. Finally, the variations of intensity of light prove to be a good indicator of seasonal variations of activity in tourist areas.

Highlights

The traditional starting point of studies of urbanization processes has been a dual vision of space with a clear differentiation between urban and non- urban spaces
Methodology to Establish the Threshold of Urban Light. In view of both our intention to study the intensity of urban land uses and the common practice in research involving this type of image [18,30], we considered it appropriate to determine the threshold value at which the brightness of a lit surface area most accurately reflects the artificialization of the land
The results obtained allow us to calculate the extension of urban light intensity in terms of both space and time

Summary

Introduction

The traditional starting point of studies of urbanization processes has been a dual vision of space with a clear differentiation between urban and non- urban spaces. These approaches have produced extremely interesting results that have often proved useful for the management and governance of a territory but have done nothing to refute the reality that nowadays a strict definition of urban limits is highly problematic in scientific terms This reality has led, in recent years, to a growing awareness that any understanding of spatial dynamics requires an analysis of urbanization as a process, rather than attempts to define a city, metropolis or region as circumscribed artifacts or areas. This process is made up of activities and social relationships in space that give rise to a complex and constantly changing network of settlements and flows of energy, Urban Sci. 2018, 2, 115; doi:10.3390/urbansci2040115 www.mdpi.com/journal/urbansci

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Conclusion