A dry summer ahead for NL

After the driest spring ever recorded, not much rain is expected this summer either, according to reports from the Royal Netherlands Meteorological Institute (KNMI).

Warm and dry summer ahead
2020, for the third year in a row, will have a hot and dry summer, with expected heat waves in June and August. Meanwhile July will get more showers, while still maintaining high temperatures. Dutch meteorologists define a heatwave as a period of five days in a row at which the temperature reaches at least 25 degrees Celsius, of which three days reach temperatures of at least 30 degrees. Weeronline weather agency, as stated by newspaper Het Parool, predicts that July will be a less hot month with more rain, a forecast that ultimately depends on wind direction. When the wind comes from the West, cooler air is blown this way than with a South or East wind.

Because of the possible lack of rain in June and August, large parts of the country will experience severe drought. This forecast could mean the destruction of many trees in the Eastern Ndtherlands, since it has been suffering from drought for three years. On average, 18.5 degrees is the forecast for this summer, a bit different from the usual 17 degrees. The expected amount of rainfall is 170 millimeters, which is 54 millimeters less than average in the summer period.

Precipitation deficit
The precipitation deficit is a way to measure drought. Specifically, it is the difference between evaporation and the amount of precipitation. So far, the spring of 2011 had the largest precipitation deficit ever recorded in the Netherlands, but this year the spring has been drier than that. According to De Volkskrant, this drought matches a fifty-year trend, in which the rainfall deficit in April and May has increased by almost 50 percent. The precipitation deficit is growing annually by an average of nearly 1 percent, or 0.57 millimeters. And this is mainly due to increased evaporation, because the amount of rainfall has hardly changed during the same period.

Peter Siegmund, a climate researcher at the KNMI, explains that the increase in evaporation is due to the rise in temperatures, more hours of sunshine and stronger solar radiation as a result of cleaner air and fewer clouds. Twice as much solar radiation results in twice as much evaporation.

Differences by region
Research by both the KNMI and Utrecht University revealed that there are regional differences in the summer droughts. While they affect the central areas more seriously and more often, on the coast the amount of summer rainfall has increased in recent decades. But Siegmund explains that those are numbers that measure other periods of the year, namely rainfall shortages in the ‘growth period’ from April to September, while the ‘new droughts’ only cover the months of April and May.

After a wet start to this year, not much rain has fallen since March. As explained in reports by the National Water Distribution Committee (LCW), the drought’s effects are most evident in the Eastern and Southern regions of the country, and have a serious effect on agriculture and nature.

Water management
Due to this precipitation shortage, the groundwater levels in these specific regions are, on average, insufficient compared to what they should be considering the time of the year. Moreover, river water cannot be supplied to these areas, and according to the weather forecast, the dry weather will continue for some time.

However, the LCW confirmed that the water management is in order so far, and the drought has no consequences for the drinking water supply through the Rhine and Meuse – although it is less than normal, it is still sufficient. “There are no blockages in the sources (ground and surface water) for the preparation of drinking water,” the Committee confirmed. Nevertheless, since May experts have anticipated the water supply via these rivers to decrease. This means that in large part of the eastern and southern regions, bans on the extraction of surface water could come into effect, as well as restrictions on the use of tap water. Since we will spend more time at home this summer, this may mean that we won’t be allowed to fill up our inflatable pools in the garden… so let’s try to find other ways to stay cool!

Written by Bárbara Luque Alanís