Drought in the Netherlands and its impact on groundwater resources

How a changing climate forces the country to reconsider current water management

When you would ask a random Dutch person to describe the weather in the Netherlands in only one word, it is very likely that this word would be: ‘rainy’. Nevertheless, probably the most pressing water-related problem that the Netherlands is currently facing, is drought. The year 2020 has already been the third consecutive year of drought, with several negative effects on (ground)water, ecosystems and soil as a result. But how come that a country that always had abundant water resources, now struggles with drought? And which interventions should be carried out to adapt to this new reality?

Multidimensional problem with multiple consequences

Three years of drought have certainly left its marks and these consequences are felt in several geographic regions and multiple sectors. For example, the economic consequences of the drought for agriculture have been severe. Especially potato farmers have been hit hard: the potato farming industry saw its income in 2018 reduced with 56%.

Risk areas in and around Amsterdam, source: Wareco, Jet de Nies/Het Parool
Risk areas in and around Amsterdam, source: Wareco, Jet de Nies/Het Parool

However, this economic impact is not only felt in the rural parts of the Netherlands, because also cities are, or will be, affected. According to estimates by the Technical University of Delft, already 30,000 houses have suffered subsidence and a prolonged drought may cause this number to increase even up to 1 million. In particular, houses built before 1970 on peat or clay soil are at high risk. For example, most of the houses in Amsterdam meet these criteria and would, therefore, be at increased risk if no action is taken.   

Peat dike [Robert Meijer | https://tinyurl.com/2r3mcuac]
Peat dike (source: Wageningen University & Research)

Droughts and consequential decrease of (ground)water levels, does not only pose risks of land subsidence. With about 55% of the entire country being located under the sea level, the Netherlands depends significantly on its dikes for flood protection. A substantial number of these are peat dikes and those are more vulnerable in case of droughts, because peat tends to shrink when water levels drop. So, the drought also increases flood risk

This year’s drought has also had its impact on the Dutch flora, more specifically the heathlands in the east of the country. These heathlands are particularly damaged this season, due to their slightly higher altitude and consequent lack of river flow compared to lower parts of the country. 

Third year of drought

Precipitation deficit: 1 April - 29 September 2020 (source: KNMI)
Precipitation deficit: 1 April - 29 September 2020 (source: KNMI)

After a rainy February, which was the wettest February in over a hundred years, the projections on the spring and summer of 2020 were very optimistic. After two consecutive years of drought, the groundwater levels had seemed to be fully recovered, which led to optimistic headlines in the news. However, only a few weeks later, that optimism faded away when some groundwater levels plummeted, and a water shortage was looming again. This seemingly sudden change, however, can be explained.  

Ecohydrologist Flip Witte did research in the historically dry and groundwater dependent provinces Gelderland and Overijssel and when interviewed by Algemeen Dagblad newspaper, he explained the rapid drop in groundwater levels. “It is probably not exclusively caused by the current lack of rain”, Witte started. “We reckon that this is the effect of two extremely dry years, 2018 and 2019, which resulted in drought in the deeper layers and is causing water to descent from the shallow layer more rapidly.”    

No lack of water

River of the Netherlands
River of the Netherlands

Unlike drought-stricken areas in other parts of the world, the Netherlands’ drought problems are not caused by a general lack of rainfall or river stream flow. River Rhine enters the country from Germany and river Meuse does the same from the south, both providing hundreds of cubic meters of freshwater per second. Meanwhile, rainfall is plentiful in autumn and winter. 

According to Niko Wanders, Researcher at Utrecht University, the main problem lies in storage of water. “We do not have any reservoirs and in some areas, we cannot infiltrate water in the top soil, because the Netherlands’ flat surface quickly floods”, he says in an interview with the Groene Amsterdammer. In the rainy periods of autumn and winter, the pumping stations run-off the surplus of water towards the sea. That is how infrastructure has always been and it did not use to cause any problems, since there was sufficient rainfall during the summer period. In recent years, however, the drier periods have increased in duration and intensity and the traditional approach may be no longer effective in a changing climate. 

Out of sight, out of mind

“If storage is not (yet) an option, you will have to spread use of the available water resources more efficiently over time”, says Wanders. But to do so, it is of crucial importance to know when, where, how often and how much groundwater is being abstracted. And, unfortunately, monitoring, especially abstraction, still remains a challenging task for water authorities. And Wanders has his views on why that is the case. “Groundwater is not a hot topic”, he says. “If the coast starts to flood, it immediately ends up on the news, but fluctuation of groundwater levels are not instantly visible.”  

On the local or province level, however, some initiatives have already started this year. Water authority Vechtstromen in the highly affected east of the country already started to divert streams and fill ditches to slow down water run-off process and water authority Delfland in the coastal province Zuid-Holland has intensified inspection of dikes. Also, the agricultural sector shows its ability to adapt to a new reality. In the province of Zeeland in the south-west of the Netherlands, for example, the production of kidney beans has substantially increased compared to last year. After two years of drought and consequent low yield, several farmers decided to cultivate more of this less ‘thirsty crop’ and reserved twice as much of their fields for these beans. 

Long-term interventions and potential solutions

Although these local measures  serve a purpose, most experts and authorities agree that more radical and structured measures are needed to adapt to a changing climate. This awareness is a good starting point for inciting actions. On actions to be taken there are, however, multiple ideas and opinions. When interviewed on national radio, Hein Pieper, Chair of water authority Rijn & IJssel, proposed a measure that would require international cooperation. Pieper proposed to collaborate with Germany in investigating options to potentially divert branches of river Rhine towards a yet to be created lake. This could then serve as storage for drier summers.

In most other solutions discussed, however, there is a crucial role for groundwater. Considering that possibly the most impacted region in the East, is located on higher land and, therefore, hard to reach by streams. Knowledge institute Deltares recently presented a plan to infiltrate water into the sandy ground of de Veluwe, a national park in this region (see interactive figure below). “Groundwater levels there are low and continue to drop”, says groundwater expert Perry de Louw. Deltares’ plan entails pumping up the surplus of water flowing in lower located rivers and artificially recharge aquifers by infiltrating it into the soil. “only 0.5% of the run-off from river IJssel already counts for 300 billion litres of water per year that could be stored underground in the Veluwe”, De Louw calculated. “That equals about 1/3 of what we abstract in the Netherlands on a yearly basis for drinking water and could provide for 6 million people.”  

This method does come with some challenges, of which the financial one is the most evident. Underground water storage involves pumping, which requires energy, and the installation of wells and pipes. “But storage above the surface is even more costly”, says Klaasjan Raat, researcher at KWR. “Also because you need to take into consideration that you would then occupy land that could otherwise be used for other purposes.” Raat also brings in an additional argument for opting for groundwater recharge over surface water reservoirs as a drought combating measure. “Water remains of higher quality when stored underground.”

With a third dry summer behind us, all stakeholders involved will get together again to discuss above mentioned as well as other potential measures to combat drought in the future. Whatever the selected interventions will be, groundwater will play an important if not a crucial role. And this will also mean that groundwater monitoring will move up the agenda. Because you can’t manage, what you don’t measure.