Urban heat transition and geosystem service provision: A trade-off? A study on subsurface space scarcity in the city of Amsterdam

The subsurface is a crucial dimension of cities' landscapes, and its qualities and structures have direct re-percussions on the urban environment above surface. However, systematic accounts of its characteristics in urban planning processes are virtually absent, rendering it an underappreciated asset because it is overlooked. When integrated in urban planning, the consideration of subsurface functions and space scarcity can improve and optimize infrastructure management and urban development. Sustainable urban development must include the subsurface as a space, and needs to account for the exploiting, preservation and occupation of that natural environment. The geosystem services approach allows for the evaluation of competing or even conflicting uses, to determine the implications for human wellbeing and sustainability. This paper looks at the implementation of heat-distribution networks in the city of Amsterdam as part of their heat-transition plan. This plan contains an order of implementation in different neighbourhoods without looking further into detail in the subsurface consequences. The present research intends to address this knowledge gap by applying an indicator for the measurement of underground space scarcity. An analysis is performed using GIS-data and detailed data from the Dutch cadastre database on the existing urban underground infrastructure to determine an infrastructure density (Urban Underground Infrastructure Density) indicator with the assumption that this may support further prioritization to determine the order of implementation. Showing the thermal interaction between heat distribution and drinking water supply pipelines furthermore points to the subsurface heat balance as an important geosystem service to be accounted for in the onset heat-transition. Finally, a quantitative analysis investigates the relationships between this indicator and other relevant socio-demographic and geo-spatial factors. This represents an important attempt to analyse the role of the subsurface in strategic masterplans and in the planning of large urban infrastructure projects. The study reports methodological find-ings, highlighting the opportunities and challenges of integrating subsurface needs into urban planning, and the necessity of interdisciplinary approaches.