News Drought
Spring drought breaks all records
Never before has it been so dry this early in the year. At least, since the measurements started in 1978. Satellite company VanderSat concludes this on the basis of satellite data that indicates how much moisture is in the soil. In 2018 and 2019, the drought started much later, according to historical developments.
Together with RTL News made VanderSat is an interactive map showing how much soil moisture is still present in your place of residence. The Dutch company uses data from various satellite data to determine the moisture level. This is expressed in cubic meters of water per cubic meter of soil. RTL Nieuws translates this into percentages. 10% moisture equals 0,1 cubic meter of water per cubic meter of soil.
New record
"The national average in May is 13% moisture", says founder and CTO, Richard de Jeu. "That is a record, because the old record from 1988 was 16%. It is now 50% drier than average." That is remarkable. At the beginning of July 2018, for example, it was 30% drier than average, De Jeu said at the time know challenges Boerenbusiness.
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2020 just started soaking wet with more than enough moisture in many places, as the data from VanderSat also shows. In April, however, a sharp turnaround is visible. According to co-founder Robbert Mica, this is due to several factors: "First of all, due to relatively high temperatures in that month, which caused evaporation to increase considerably. But things such as solar radiation and wind can also play a role." VanderSat uses satellites to measure the amount of moisture in the top layer from 0 to 15 centimeters. It uses calculation models to determine how much moisture is in the root zone (up to 50 centimetres).
Other measurement method
Mica explains: “It is a new way of approaching drought. We are all familiar with the precipitation deficit maps. potential precipitation deficit† That is the difference between the amount of precipitation and what is potentially evaporating. The soil moisture approach is an alternative. Based on satellite observations, it is directly measured how much moisture there is in the top layer of the soil, by taking into account soil conditions in addition to precipitation and evaporation. For example, insurers worldwide use our data for drought insurance. It is also used for irrigation advice and crop protection."
Scientists have been using the technology since the 70s, but mainly for climate research. Five years ago, VanderSat changed this. By comparing the data from several years, it is easy to see how the situation is developing. The higher sandy soils clearly stand out. It is also very dry in Zeeland. There is more moisture in the soil along the Wadden coast. "It doesn't look very extreme on the map, but a different shade of brown means a big difference in the moisture status," says Mica.
Irrigation
Irrigation is something that the measurement technology takes into account to a limited extent. Mica: "This is very difficult for us to detect. Because, does the satellite just pass after irrigation or are there a few hours in between? The evaporation is also higher after irrigation. The peak in the top layer then disappears quickly. our data is 100x100 meters, that sounds like a lot, but remember that climate scientists use data with a resolution of 25x25 kilometres, so our data is of a very high resolution. "
The company cannot say whether the soil will continue to dry out. They don't make weather forecasts. Data for the past 5 years shows that the situation improves slightly in June, only to dry out further in July. On average, this is the driest month, after which the map changes to light brown again and the soil moisture content increases.
Niels van der Boom
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