he prolonged heat and dryness during the summer of 2018 resulted in water shortage all across Europe. This was especially valid for the Netherlands, where the 2018 drought was considered as one of the worst droughts of the past century with a precipitation deficit of approximately 300 mm. The drought significantly affected crop yields and several national water authorities had to take action to control the water levels, including irrigation restrictions.
Unfortunately, it is not easy to quantify a drought. Traditionally this is done with rainfall observations and potential evaporation, but within the water and agricultural sector a drought is more associated to the actual water conditions in the soil rather than solely precipitation deficits which are not based on actual evaporation.
With the recent advances in both technology and algorithm development we are now in the position to quantify these conditions using sophisticated satellites of NASA and ESA. In the figure below we show the severity of the drought for each municipality in the Netherlands using a multi-year satellite soil moisture record. The municipality of Emmen in the eastern part of the Netherlands showed the highest vulnerability to this drought event. At the end of May 2018, the soil moisture conditions in the Netherlands dropped below normal conditions and it stayed there for almost 10 months. Because of the rain storms over the past weeks, soil moisture values are now brought back to normal levels.
However, we have to be careful whether this is sufficient moisture to recharge the depleted groundwater levels. With our operational service we can keep a close eye on these levels at a daily basis. Besides the Netherlands, this satellite derived drought monitoring service is used in other countries, including Kazakhstan, the US and several countries in Europe and Africa.