Optimising subsurface use for future cities

The subsurface is a dynamic environmental system influenced by the surface through the interaction of heat, water, chemical and biological phenomena and physical stresses. The urban environment modifies the natural link between the surface and the subsurface by interacting and changing the surface drivers or by directly changing the structure of the subsurface. Similar to the concept of ‘ecosystem services’ (see Ehrlich and Ehrlich, 1981) the urban subsurface may be considered as a resource that can provide several services (Bobylev, 2009). Although we consider the urban subsurface as a single resource, it may be subdivided into four resources relating to: construction space, geo-materials, groundwater and geothermal (Parriaux, 2007). It has long been recognised that the urban subsurface is a complex, scarce and valuable resource.