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The accumulation of dry years threatens animals and plants – but also agriculture. A pilot project should help.
Hydrologist Massimiliano Zappa says he cannot make a forecast for this summer as to how dry it will be. “I still don’t have an answer as to whether you can set off fireworks in 2022 or not.”
Zappa, who works at the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), has been collecting data on drought conditions in Switzerland for many years.
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These days it can get up to 36 degrees hot in Switzerland. This brings back memories of the summer of the century in 2003 or the years 2015 and 2018, when it was not only hot but also very dry.
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Zappa plays a key role in the national early warning system, which the Federal Council now wants to expand. “We have been running a prototype for the early detection of critical drought for over ten years. This is primarily based on current measurements.” Water scarcity doesn’t just happen in a few days, but is based on various factors – some of which can be identified early on.
Poor snowmelt can be fatal
For example, there is the development and the current status of the groundwater level. After the extremely wet last summer, the water level was at its absolute maximum. Now it is plus-minus in the normal range in many parts of Switzerland. Then there is the snow factor.
How much it snowed in winter is crucial for the water situation in the following spring and summer, explains Zappa. “For example, a river can carry 300 cubic meters of water per second in spring and 100 in winter. But if it carries 200 cubic meters instead of 300 in spring, that is a third less than usual. That means that maybe the snowmelt is missing. » That is exactly what can be seen in some places in Switzerland this year: a meager snowmelt.
There are already some locations with temperatures above 18 degrees. If the water supply is small and the air temperature is hot, a situation can quickly arise in which the fish no longer feel comfortable.
Many bodies of water – lakes, rivers, streams – were currently carrying less water than usual. And because of the currently dry days, this situation will get worse, especially in the Mittelland and Ticino. “There are currently some locations with temperatures above 18 degrees. If the water supply is low and the air temperature is hot, a situation can quickly arise in which the fish no longer feel comfortable.”
When the only source of water runs dry
Some affected regions have therefore already reacted. In the canton of Aargau, for example, garden centers and farms are no longer allowed to take water from certain bodies of water. In the canton of Ticino, for a few weeks now, posters have been urging residents to use as little water as possible.
Saving water is definitely an efficient means, according to Zappa. Especially if it’s used early. The national early warning system for drought can help here. “Especially communities in which the water supply is not redundant, they have bigger problems when the only water source runs dry.”
These communities would then know in which years they should use their water particularly sparingly. But it would also make sense for other regions to use water more sparingly in the future, says the hydrologist, who has been collecting and analyzing data on the water situation in Switzerland for years. The trend is clear: in the long term it will not only get hotter, but also drier.