Climate change poses serious challenges to urban areas by increasing occurrence of heat waves, drought, heavy precipitation and extreme high sea level events. These changes affect physical infrastructure, water supply, energy provision, transport and industrial production, hence resulting in a variety of ripple effects across different sectors of the city life. However, when properly planned and managed through the appropriate governance structures, cities have the potential to diminish the causes of climate change and effectively protect themselves from its impacts. In this complex scenario, the DECUMANUS Land Monitoring Services provide novel Earth observation (EO) based products which allow to reliably characterize built-up and paved surfaces, as well as urban green areas. In particular, they allow urban planners to better understand, assess and take action on climate change both at the regional and local level. Presently, similar land-monitoring products are generally extremely costly and time demanding for the municipalities being them mostly carried out by photointerpretation of very high resolution airborne imagery or in situ surveys by experts. Instead, the implemented services rely on completely automatic algorithms where the support of an operator is eventually requested only at the end of the processing chain to visually check the outputs. This results in sensibly lower costs and shorter time, but also allows an easy and straightforward update once provided with new suitable data.
>> Current and Potential Green Roof Mapping
>> Tree Location and Canopy Mapping
>> Spatio-temporal Urbanisation Mapping
>> Impervious Mapping
User feedback and usability
With the Basic Services, urban planners are provided with key information about the temporal growth of built-up areas along with the extent of impervious surfaces; moreover, with the Premium Services, they are supplied with maps of current and potential green roofs as well as of tree locations and their canopy coverage. This suite of products is of very high importance for improving mitigation and adaptation planning strategies aimed at reducing stormwater runoff (which transports toxic chemicals, dirt and trash from roofs and roads into lakes, streams and rivers but also leads to an increased occurrence of urban flooding events), lowering air pollution (which is responsible for a variety of respiratory and cardiovascular conditions), mitigating the urban heat island effect (which causes high-energy consumption for cooling and an increase of heat-related illness and fatalities), as well as enhancing the wellbeing and quality of life of urban residents.
Example Premium/Local Products:
Current and potential green roof mapping:
Green roofs are gaining increasing attention as a versatile new environmental mitigation technology. In particular, they exhibit several advantages, like absorbing rainwater, providing thermal insulation, increasing energy efficiency, as well as reducing air pollution, electromagnetic radiation and noise. In this context, a dedicated DECUMANUS Premium Service has been implemented aimed at identifying actual green roofs and determining which roofs can be potentially converted into green roofs along with the corresponding expected impact (which is of high support to green urban planning policies and might help the municipality to target subsidies in areas which would more benefit from this change). Specifically, a novel technique has been developed based on the employment of very high resolution satellite/airborne color infrared (CIR) remote sensing data and height information, where the support of an operator is mainly requested only at the end of the processing chain to visually check the results.
Current and potential green roofs overlaid to CIR airborne imagery (left), estimated potential green roof impact (right) for a subset of the Royal Borough of Kensington and Chelsea.
Tree location and canopy mapping:
In several cities it occurs that no or incomplete trees inventories are available directly at the municipality. However, this source of information is important for a comprehensive knowledge about urban green areas, which is fundamental for improving mitigation and adaptation activities against climate change as the reduction of air pollution and the urban heat island effect. A specific service has been developed in DECUMANUS which allows to routinely create a reliable map of the tree location and of their canopy in a given study area without the need for manual work. Specifically, the service exploits airborne CIR imagery, along with digital surface and digital terrain models (DSM and DTM) for the study area.
Tree canopy coverage (left), and tree locations (right) derived for a subset of the Royal Borough of Kensington and Chelsea.
Example Basic/Strategic Products:
Spatio-temporal urbanisation and imperviousness mapping:
To reliably delineate the extent of built-up areas over time in the last decades is of great importance for properly modelling the temporal evolution of urbanization and, thus, better estimating future trends and implementing suitable planning strategies. However, urban growth is associated not only to the construction of new buildings, but also to a consistent increase of all the impervious surfaces (hence including roads, parking lots, squares, pavements or railroads), which do not allow water to penetrate, forcing it to run off. In this context, two specific DECUMANUS Basic Service has been developed which aim at delineating the past urban area extent by means of ESA radar imagery and effectively estimating the percentage of impervious surface from multitemporal Landsat data, respectively. Corresponding products are generated at 30m spatial resolution.