The spread of droughts is difficult to predict
Published: Monday, Mar 25th 2024, 11:21
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The course of a drought is more difficult to predict than previously assumed. When it doesn't rain for a long time, river levels behave differently to groundwater levels, as Swiss researchers have shown in a study.
For water management, for example in agriculture, it is important to understand exactly how droughts spread, wrote the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) in a press release on Monday.
In their study, which was published in the journal "Geophysical Research Letters", the researchers showed that too little rain - a so-called precipitation deficit - leads to low water levels in rivers in every third case. This in turn has a negative impact on groundwater in 40 percent of cases. Data from 70 river catchment areas in Central Europe served as the basis for these findings.
Researchers surprised
With this spread, the effects of droughts become more severe, as the researchers wrote in the study. If a drought also affects rivers and groundwater, it can no longer be compensated for by pumping water for irrigation.
The longer it doesn't rain, the further the drought spreads spatially. What surprised the researchers, however, according to the press release, is that this only affects the water levels of the rivers, but not the groundwater. Even if the rivers have dried up, neighboring groundwater reservoirs may still be partially filled.
Large number of influencing factors
This can be explained by the different soil structures, explained the WSL. As porous material allows water to seep away more quickly than loamy soil, for example, there are delays in the spread of drought depending on the area. In addition, aquifers can store a lot of water, which is why they are often not affected by drought.
"The large number of influencing factors makes it difficult to accurately predict whether a prolonged dry period will lead to dried-up rivers or a groundwater shortage," study author Manuela Brunner was quoted as saying in a press release.
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