The final piece of the drinking water supply puzzle
Expert(s) |
Geert-Jan Nijsten
Demand for drinking water continues to rise due to population growth, increased consumption and climate change. Our current sources provide us with a reliable supply of drinking water, but they may come under pressure in the event of major disasters. That is why we are working on National Groundwater Reserves (NGRs).
The pressure on the water supply in the Netherlands is increasing, even though water seems to be a given. We are simply facing longer dry spells. “We need to start thinking now about how we will ensure safe and clean drinking water flows from the tap in 2100,” says Geert-Jan Nijsten, groundwater expert at Deltares.
Together with TNO, Deltares is mapping out the National Groundwater Reserves: mostly deep-seated, unspoilt freshwater reserves to help address future drinking water shortages. The Netherlands currently obtains two-thirds of its drinking water from groundwater.
We need to start thinking now about how we will ensure safe and clean drinking water flows from the tap in 2100.
Geert-Jan Nijsten
Current sources are protected by strict regulations. The origins of the NGR plan lie in the 2014 Drinking Water Policy Document. Provinces were required to designate search areas to expand the drinking water supply towards 2040 – the so-called Supplementary Strategic Reserves. In addition, the national government designates the NGR.
Deltares and TNO are investigating mostly deep-lying fresh and brackish water reserves that are free from contamination. Using advanced 3D models, we map the location, qualities, and risks, and advise the government on the demarcation of these areas and on strategies to protect these reserves
Geert-Jan: “The NGR is the final piece in our drinking water supply. These are reserves that we will only need in decades’ time – or in the event of a national disaster. Think of an environmental disaster that leaves large sections of the population without access to safe drinking water.”
Deeper freshwater reserves
TNO and Deltares are searching for deeper freshwater reserves, free from contamination such as fertilisers or pesticides.
Jan Gunnink, researcher and project manager at TNO: “We have identified where clean drinking water is located in the ground and wanted to know: how deep is the water, how much of it is there, and what happens if we pump it up? Is it deep enough and well protected, because then the space above or below it can be used for other purposes, such as generating renewable energy via geothermal energy, for example.”
Three-dimensional maps and models are used for this purpose. These not only show the location of the reserves but also the effects of extraction, such as a drop in the groundwater level or the risk of salinisation.
“Structural extraction must not harm the natural environment,” emphasises Jan. “If you extract groundwater, the upper groundwater layer drops, posing a risk of damage to nature. That should only be done in extreme emergencies, such as a major disaster. Then it really is a last resort.”
Promising reserves in the North and East of the Netherlands
The preliminary results show that the most promising reserves are located in the North and East of the Netherlands. In the west, the water is often too brackish due to the infiltration of salty seawater. Distribution across the country is important: in the event of a disaster, every region must have access to clean water.
“It makes no sense if all the reserves are located beneath the Veluwe; that would be of little use to Limburg,” says Jan. The initial survey in 2015 was still just a ‘pencil sketch’. It has since grown into a major research programme. The Ministry of Infrastructure and Water Management (IenW) is incorporating the recommendations into the Soil, Water and Subsurface programme. Geert-Jan: “We provide knowledge and maps, but the final demarcation of the NGR and any protection level is a political and administrative decision.”
From policy to practice at the table
The search for new drinking water supplies is complex. Drinking water is important, but the subsurface is also needed for geothermal energy. Geert-Jan: “Stakeholders want to protect drinking water and keep the land usable for other purposes.” TNO and Deltares complement each other: TNO maps the geological structure and modelling, whilst Deltares investigates the effects of extraction on water quality and nature.
We are collaborating on this with drinking water companies, provinces, water boards, sector organisations for ground source energy and geothermal energy, the Ministry of Infrastructure and Water Management, and the Ministry of Climate and Green Growth (formerly Economic Affairs and Climate Policy). “The breadth of the advisory group is unique,” says Jan. From policy to practice – everyone is at the table.
Impact of this research
Partly on the basis of research results, the government decides on the formal demarcation of National Groundwater Reserves and further policy measures for their protection. The Netherlands will have a robust, future-proof system of drinking water reserves, deployable in the event of large-scale disasters and as a potential long-term structural supplement to existing reserves. In this way, future generations can also count on sufficient drinking water.
