20 July 2023 at 05:12
While many countries suffer from extreme weather conditions, the Netherlands remains cool and relatively wet. Reason for cautious optimism, experts say to NU.nl. But there is still no question of a drought-free summer.
The weather in the Netherlands has been changeable for some time now: it is sunny, not very warm and there are regular showers. Good news for the drought, you might think. But the rainfall deficit is still increasing.
Prolonged drought is bad for nature and people. This can lead to water shortages, which is bad for agriculture and can lead to a shortage of drinking water.
At the moment, since the start of the dry season (which starts on April 1), more water has evaporated than has fallen back to the bottom. So on balance we have too little rainfall. “The precipitation deficit is still high,” says climate expert Peter Siegmund of KNMI. “Between the beginning of May and mid-June there was simply not enough rain.”
The good news: precipitation shortages in the summer are not uncommon. In the summer, the sun shines more often than it rains. “Since mid-June, the precipitation deficit has increased at a normal pace.” But because of the hot weeks before, we are all in all still around the level of the 5 percent driest years.
What is Precipitation Deficiency?
Precipitation deficit is the simple calculation of the precipitation minus the water that evaporates again. If more water evaporates than is added via precipitation, the precipitation deficit increases. Precipitation and sunlight are particularly important factors. A cloudy day therefore helps against the precipitation deficit. Heat (temperature) plays a relatively minor role.
Precipitation shortage will decrease in the coming weeks
The ‘Dutch summer’ (with occasional showers) is expected to last for a while. The weather forecast for the next two weeks remains changeable, and we can cautiously count on sufficient precipitation to even reduce the rainfall deficit somewhat.
The precipitation predicted for the coming weeks will certainly have an impact, Siegmund expects. “It will really rain a lot in the coming weeks, a bit every day. Then there will be more rain than evaporation.”
Photo: NU.nl/Bart-Jan Dekker
Little to say about long term
It is very difficult to predict whether this favorable weather will last any longer. The KNMI looks at the weather forecast two weeks in advance and anticipates it. “Seasonal forecasts over several months are just very difficult,” says Weerplaza meteorologist Roosmarijn Knol. She also says that the most reliable weather forecast does not go beyond two weeks.
“There are strong signs for the next three weeks that we will experience westerly winds, which will bring air across the ocean.” This means that the Netherlands will probably have to deal with “moderate summer weather” for some time to come, Knol expects.
According to Knol, this means that there is little chance that the extreme weather in many other places in Europe will come our way. But it cannot be ruled out. “The heat is building up there very much. It only takes a small change in the wind direction to burst the ‘bubble’ and the heat will come this way.”
Groundwater level dependent on human interference
In times of drought, it is important to distinguish between surface water and groundwater. Both determine how dry or wet a certain area is.
With surface water you should think of ditches and streams. The water that is deeper in the soil and can be pumped up (for example for agriculture, construction work and drinking water) is called groundwater.
In principle, the groundwater level rises when there is more rainfall. But when more water is pumped up, the groundwater level drops faster. This happens, for example, in times of drought, when farmers need extra water for agriculture.
The groundwater level is also influenced by regulation by water boards. They drain surface water. In the winter, water is often drained too quickly, leaving too little in the summer and the groundwater level is too low.
Groundwater levels vary from region to region
The groundwater situation is currently better than in previous years. This is partly due to the return of the rain in June, but also because the spring started wet. Less water is also discharged in the winter than in previous years.
But it is important to emphasize that the groundwater level varies by region. More water is pumped up in one region than in the other. At the moment, especially Drenthe and the north of Overijssel have to deal with a groundwater level that is too low.
Moreover, not every region receives the same amount of rain. “The showers in the summer are quite local in nature,” says Weerplaza meteorologist Knol. As a result, a shower can easily lead to a decrease in the precipitation deficit in one place, while it remains dry a few kilometers away.
Also, not every soil is equally sensitive to drought. This is especially true for the sandy soils in the east and south of the country, from Drenthe to North Brabant. Clay soils in the west, center and north of the country can retain moisture better.
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2023-07-20 03:12:35
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