A healthy groundwater system as a guiding principle in spatial planning and management of water, land and subsurface in the Netherlands

Abstract

Groundwater in the Netherlands is subordinate to increasingly intensifying land use practices and water usage. As a result and exacerbated by climate change, groundwater quantity and quality are decreasing, and associated ecosystem services (e.g. nature, drinking water and stability of built environment) are under pressure. To reverse this trend, groundwater needs to be treated in a more sustainable manner.

This research presents an integrated, up-to-date, national picture of the current situation of groundwater quantity and quality in the Netherlands, including five main groundwater threats as well as related solution strategies that help restore the groundwater and enable its sustainable usage on the longer term. The methodology underpinning this research is composed of expert sessions, a literature study and a national scale data analysis.

Results show that nature areas in the sandy, free-draining areas have dried up and are further desiccated; a significant increase in groundwater levels is needed to restore the groundwater systems in these areas. Three categories of measures are effective when wetting these areas: measures that ensure that the precipitation surplus is retained in the area for longer, measures that reduce groundwater extraction and measures that ensure that groundwater recharge is increased.

Good groundwater quality is crucial but is under pressure. Although limiting emissions and tackling sources are the main priorities, contamination risks can also be limited by making better use of natural physical, biological and chemical barriers in the subsurface.

The use of groundwater for thermal energy has potential, but energy activities must not have a negative influence on groundwater quality. Especially in the areas where groundwater is the main source of drinking water (sandy areas), risks are relatively high. By creating detailed three-dimensional insight of the subsurface, resilient and vulnerable zones can be detected. This can help to utilise the potential of subsurface energy whilst decreasing risks of contamination.

Urban areas and the built environment are very susceptible to damage and nuisance resulting from changing groundwater levels, especially in areas with slack soils. To future-proof urban areas, taking into account changing groundwater regimes when (re)constructing buildings and infrastructure and avoiding areas vulnerable to land subsidence and groundwater flooding are key principles.

Freshwater demand (from groundwater) in the Netherlands is high and is further increasing. To safeguard sufficient fresh groundwater supply in the future, its use must be reduced and limited to high-quality applications, and groundwater resources must be protected. Moreover, replenishing of groundwater is a key measure to safeguard future freshwater supply and can be realised in the subsurface higher parts of the sandy areas as well as in the salt/brackish subsurface of the coastal zones.

To conclude, protection and restoration of groundwater resources as well as the transition to sustainable groundwater use requires adjustment in the use and management of water, land and subsurface. The agricultural transition and energy transition as well as innovations in the built environment offer opportunities for this.