GEOSYSTEM SERVICES AND COST-BENEFIT ANALYSIS TO SUPPORT A SUSTAINABLE SUBSURFACE PLANNING AND UTILIZATION

The subsurface constitutes a multifunctional natural resource that provides physical space, water, energy, materials, habitats for ecosystems and support for surface life, as well as acting as a repository for cultural heritage and geological archives. However, it is often “out of sight and out of mind” unless extraordinary opportunities or risks are present. Possible uses of subsurface resources can be competing or coexisting. Exploitation of one subsurface resource may inhibit opportunities of using other subsurface resources, or limit the benefit humans might otherwise derive from the subsurface, compromising fair inter- and intragenerational distribution and sustainable development. To support a more holistic subsurface planning approach, the concept of geosystem services (GS) has been suggested as a tool to highlight services from the subsurface (or which the subsurface provide), as a complement or parallel to how ecosystem services (ES) acknowledge the contribution of biotic part of nature to human well-being. We present the concept of GS together with cost-benefit analysis to assess the societal profitability of competing subsurface interests, exemplified in a case study with a road tunnel constructed through a horst. The societal benefit of the tunnel is a reduction in travel times with up to 7 minutes, which is competing with the reduced benefits of the services the natural groundwater system provides. Due to leakage of groundwater and subsequent groundwater drawdown from constructing the tunnel, a change in the natural system will be induced. Consequences (costs and benefits) of constructing the tunnel are a result of the hydrogeological conditions in the horst. Consequences, constituting both market and non-market goods (economic, social and environmental), are identified and described qualitatively. The case study provides a tangible example of the relation between competing interests when exploiting the subsurface and provides a pedagogical example of how a cost-benefit analysis (CBA) approach can be used to weigh competing interests to assess the societal profitability of different usages of the subsurface. The case study constitutes a starting point for a discussion on possibilities and challenges of using CBA as a decision support for sustainable subsurface planning.