Opening up the subsurface for the cities of tomorrow
The subsurface is an important constituent of the physical environment of cities. We live on top of it; building and construction have to deal with the structure and properties of the subsurface, and occasionally with the hazards it presents; and we benefit from, and in some cases are dependent, on many of its ecosystem services. Cities not only expand outward and upward, but also downward. More and more, subsurface space is being used to relieve the increasingly crowded and congested urban surface. The more use we make of subsurface space, the more surface space we free up for the one function that cannot do without daylight and fresh air: living.
COST (European Cooperation in Science and Technology) Action TU1206 Sub-Urban explores sustainable use and management of the urban subsurface, and the use of subsurface information in urban planning and development. The importance of appreciating the importance of the ground beneath cities may seem self-evident, but studies by the Action’s Working Group 1 have confirmed that the urban subsurface is in fact still largely ‘out of sight, out of mind’. It does not present a daily concern to city planners and managers, and when it does, there is often trouble. The Action has identified a knowledge and communication gap between subsurface experts, urban planners and decision makers. We argue that the only possible way to bridge this gap is to provide the right type of subsurface information, in the right format, and at the right time and make sure that the people receiving the information (urban planners and decision makers) are able to understand and use the information to take decisions. The overall challenge in “Opening up the subsurface for the cities of tomorrow” is to be able to:
· On one side - to understand and identify the city needs in order to develop/provide appropriate knowledge and products/tools for the municipality, city region, water board or other end-user, and
· On the other side – to identify good practice and relevant technologies when mapping and modelling the subsurface of the urban areas to enable improved and sustainable use and management of the urban subsurface.
This report describes the background to, and examples of, good practice, and tools that can realize these challenges. Taking the outputs from Working Group 1 (the ‘state of the art’) as a starting point, Working Group 2 has evaluated the knowledge needed to characterise and understand the urban subsurface (including the man-made infrastructure, artificial soils, and natural geological features) by means of a variety of good practices and techniques and identified knowledge gaps. This report summarises findings on: Subsurface information and planning; Data acquisition and management; 3D geological modelling of the subsurface; Groundwater and geothermal monitoring and modelling; Geotechnical modelling and hazards; Subsurface geochemistry; and Cultural heritage.
Taking the perspectives both of urban planning and subsurface geoscience, the report identifies urban needs, gives examples of current good practice and best efforts for a wide range of subjects: from identifying city needs; to methods to achieve, store and visualize geological and geotechnical information, and to ways in which sub-surface-related issues can be brought into urban planning. The examples provided describe practices both on municipal and national scales for different geographical settings/typologies. The report also identifies key knowledge gaps in relation to each topic. The good practices and key knowledge gaps are presented in summary tables.
We propose the Geo City Information Modelling (GeoCIM) concept, which expands on Building Information Modelling (BIM) and the City Information Model (CIM), as a tool that can bring together effectively above- and below-ground data and knowledge at scales appropriate to city needs, and also an explicit requirement of sustainable urban planning and management.
Working Group 2 has, besides this summary report and a number of detailed reports, provided the essential framework for the Toolbox being developed by the COST Sub-Urban Action’s Working Group 3.
In addition to the concrete results, COST Action Sub-Urban has been successful in creating a community of practice between the geoscience and planning communities, involving cities, universities and institutes.
To some extent, the project is already improving conditions for urban subsurface planning, especially where communication, mutual understanding and awareness raising are concerned. For better impact, however, this will have to be extended to decision makers and the general public.
Assessments of cost- and time-benefits of the rationale behind the systematic inclusion of the subsurface within planning and other decision making (requiring data, databases, modelling, decision support systems, monitoring etc.) has not been undertaken here, but needs to be explored.