Dutch grasslands have been hit hard by drought this summer. Large areas of grass have withered, particularly in Zeeland, western Brabant, Limburg, Texel and the Achterhoek. Satellite imagery from Wageningen Environmental Research's Groenmonitor reveals where drought stress is most severe. The damage is now greater than during the dry summer of 2022, although it has not yet reached the levels seen in the record-breaking drought of 2018.
Anyone travelling through the Netherlands this summer can see the landscape gradually changing colour. In many places, green pastures are giving way to yellow and brown grass. But how severe is the drought damage exactly? And are the effects equally pronounced across the country?
The Groenmonitor, developed by Wageningen Environmental Research (WENR), enables researchers to track these changes from space. Satellite images are converted into a so-called vegetation index, which indicates the amount of green biomass present. This makes it possible to monitor vegetation development down to individual field level.
"Of course, we can see with the naked eye that conditions are dry, but satellite imagery shows us where the impacts are greatest and how the situation develops over time," says WUR researcher Gerbert Roerink. "This allows us not only to compare regions, but also to compare this summer with previous drought years."
From green to yellow on Texel
A grassland field on Texel clearly demonstrates what the Groenmonitor can reveal. In July 2024, a year with more than sufficient rainfall, the field was still completely green. Its growth curve shows three distinct drops caused by mowing. After each cut, the grass regrew and the vegetation index increased again.
This year, the curve looks very different. After a second cut at the end of June, growth virtually came to a standstill. Due to the lack of rainfall, the grass was barely able to regrow and the vegetation index continued to decline. By mid-July, the above-ground grass on the field had died back and turned yellow.
Satellite images from August clearly show the contrast: where green pastures could be seen two years ago, withered grass now dominates.
Major regional differences
To assess the situation across the Netherlands, the researchers analysed satellite imagery from June, July and August. For grassland fields, the average vegetation index was calculated for approximately 40,000 areas with similar soil and water management characteristics.
At the end of June, grass across most of the Netherlands was still relatively green. By the end of July, clear regional differences had emerged. Severe drought stress was already visible in Zeeland, Limburg and on Texel. By August, drought stress had intensified in these areas and spread further across the country, including to the Achterhoek, the Veluwe and western Brabant.
The patterns shown by the Groenmonitor largely correspond with the precipitation deficit recorded by the Royal Netherlands Meteorological Institute (KNMI). Grass in Groningen and Friesland, for example, remains relatively green, while the precipitation deficit in Zeeland is considerably higher. The peat meadow areas of North and South Holland also stand out because their grass remains relatively green. Higher water levels in the ditches mean that more water remains available to vegetation in these areas.
2026 is the second-driest summer for grasslands this century
The Groenmonitor also makes it possible to compare the impact of different drought years. The researchers compared the current situation with the dry summers of 2018 and 2022.
The analysis shows that 2018 was still considerably more extreme for grasslands. In August of that year, drought stress was visible across almost the entire country and the impact on grass was more severe.
So far, the summer of 2026 ranks second. Drought stress this year is clearly more severe than in 2022, but less severe than in 2018. Whether that remains the case will depend on the weather in the coming weeks. As long as the drought continues, the Groenmonitor will continue to track changes in vegetation.
Beyond grasslands
Although the researchers focused on grasslands for this analysis, the Groenmonitor can be used to monitor many other types of vegetation. Satellite imagery can, for example, provide insight into the effects of drought on agricultural crops and natural vegetation.
The extent to which plants are affected by drought depends on factors including crop characteristics, soil conditions and rooting depth. By comparing satellite data across multiple years, researchers can gain an increasingly detailed picture of where vegetation is vulnerable and how drought develops across the landscape.
The Groenmonitor is publicly accessible and provides up-to-date satellite information on vegetation development across the Netherlands.
