The world population explosion is accompanied by rapid urbanisation causing urban sprawl. Since 2008, for the first time in the history of humanity, over half the population has been living in an urban environment. In 2050, it is estimated that around 70% of the world’s population will be city-dwellers. This urbanisation will weigh heavily on natural resources globally, with tensions over available land, habitats and biodiversity. Food demands should double, power consumption increase by 80% and water supply needs by 55%… These huge challenges will only be met if efficient cities are planned, capable of synergy between consumption and production. In view of these challenges, it has become vital for numerous operational applications to monitor artificialisation, and to detect and characterise urban change. In such circumstances, remote sensing represents an extraordinary wealth of information.
Satellite images are a source of value-added information (in terms of spatial, temporal and spectral resolution) that needs to be fully exploited today so as to rise to these numerous challenges.
Cities are complex systems and their impact on the environment is measured in various areas such as artificialisation, biodiversity, air and water quality, noise and global warming among others. Through the variety of images available, remote sensing can draw up inventories, perform impact studies, monitor areas or events over time and contribute to territorial planning. The research issues to be explored are both scientific and methodological, and include:
- characterising urban morphology and change: the impact of urban areas on radiation and energy exchanges between the urban surface and the urban canopy needs precise knowledge of the types of surfaces and materials used in construction. Multispectral or even hyperspectral images with high or very high spatial resolutions can provide the information needed for meteorological models and stimulate progress in determining the impacts that an urban area has on its environment;
- monitoring urban sprawl reveals its progression and may be used to calculate several indicators such as the artificialisation of surfaces or consumption of farming areas. These spatio-temporal indicators can then be used to improve the implementation of urban development strategies;
- identifying vegetation in urban environments: the issue of vegetation in cities has been of increasing interest these past few years in relation to several themes such as the wellbeing of urban populations, the quality of living conditions or the impact of plant cover on the intensity of urban heat islands and, more generally, global warming.
- for natural and/or manmade hazards, remote sensing may be used to inventory and characterise the stakes and elements at risk. By identifying structural challenges and natural or other amenities within the area subject to such hazards, it is possible to implement strategies for adapting these areas with respect to the risk they run.
CNRS |Université de La Rochelle
- PAYTAL project (Paysage et étalement urbain: dynamiques physique et culturelle et modélisation – Landscape and urban sprawl: physical and cultural dynamics, modelling) (2011-2014): this project was designed to study the relationship between urban sprawl and the changing landscape. Its multidisciplinary approache aimed to couple economic analysis methods (urban economics), spatial methods (geomatics and remote sensing) and landscape perceptions. Using computer tools (data mining and classification), the project aimed to accurately describe the morphology of urban sprawl and landscape dynamics.
- From a methodological viewpoint, the COCLICO project (COllaboration, CLassification, Incrémentalité et COnnaissances – Collaboration, classification, incrementality and knowledge) (2012-2016) aims to propose a generic, innovative method for the multi-scale analysis of large volumes of spatio-temporal data guided by knowledge of a particular theme, especially in the urban environment. Data mining appears an appropriate solution for choosing the methods and parameters to use in a processing chain from raw data to knowledge
More information on the COCLICO project
- More topical, the VegDUD project investigated the role of plants in sustainable urban development. The approach was related to challenges linked to climatology, hydrology, control over energy and ambiance (2009-2014). This project, supported by the IRSTV Institute for Research on Urban Sciences and Techniques, was divided into six components, one of which focused on urban physiography. Researchers carried out methodological evaluations to investigate the impact of spatial and spectral resolutions, and choice of image analysis methods to extract vegetation in an urban context accurately while meeting the needs of atmospheric or hydrological models using this satellite information.
More information on the VegDUD project
- The VALI-URB project funded by BELSPO (2012-2014) was designed to put forward reproducible analysis methodologies in order to characterise urban change and accurately identify and characterise ecological corridors through high and very high spatial resolution satellite imagery. Jointly funded by CNES, images from the new Pleiades satellites were used.
More information on the VALI-URB project
- The MAMUD project funded by BELSPO (2006-2011) also used high-resolution images and medium-resolution time series to measure the impact of urban growth on the landscape structure and residents’ access to green areas.
More information on the MAMUD project
- The project supported by the PNTS-INSU in 2009 investigated urbanisation and the changing landscape of Strasbourg from 1986 to 2006. Its main goal was to identify, characterise and quantify changes to the landscape due to urbanisation of the countryside around Strasbourg and the Urban Community (CUS) over a 20-year period from 1986 to 2006. It thus revealed the advance of urbanisation, the form it took and the urban renewal process by rehabilitation or densification of the urban fabric.
More information on this project (Urbanisation et changement du paysage à Strasbourg entre 1986 et 2006), see: Urbanisation et changement du paysage à Strasbourg entre 1986 et 2006
- The spatial indicators project (Indicateurs Spatiaux, 2010) aimed to propose a methodology for producing and evaluating spatial indicators focusing on land cover and use linked to the peri-urban Mediterranean in order to support accompany regional planning schemes.
More information on the Spatial indicators project