Abstract
This viewpoint argues that for sustainable urban development the relationship between the city and the ground beneath it needs increased attention. The underground volume might provide additional urban space, but it cannot be treated in the same way as above-ground space. Cross-disciplinary research and professional collaboration are needed to better understand (a) the variety of processes at play, and (b) the role of geotechnical engineers and geoscientists in working towards sustainable underground urbanism.
1. Introduction
With ongoing urbanisation, the pressure on land use is growing. Between 2012 and 2018, the annual average of newly developed land was 540 km2 (EEA, 2019). One measure being advocated to counteract this continuous land take is the regeneration of brownfield sites (EC, 2016). This directly ties future urban development and redevelopment to the suitability of the ground present and to human ability to improve its current condition. In addition to brownfield utilisation, several aspects of urban development rely on the subsurface and our ability to change the subsurface environment. The availability of groundwater, to give an example, has often been a determining factor for the establishment of new settlements. The abstraction of groundwater for urban development can cause secondary effects such as land subsidence or saline water intrusion (Foster et al., 2011) and, in turn, have a severe impact on the built environment present.
