The latest developments
In April, the Swiss Mittelland hardly got any rain. The temperature was up to two degrees above average. The situation in Ticino is particularly tense: the last significant rainfall there was in November.
The situation in Ticino is particularly tense. The last significant rainfall there was in November 2021. In the picture: The low water level of Lake Lugano.
The latest developments:
- From Friday (April 22nd) the long-awaited rain should fall in Ticino. As Meteo Schweiz writes, 40 to 80 millimeters of precipitation is expected in the south within 48 hours next weekend. However, there is still a relatively high degree of uncertainty with regard to the amount of rain. Since autumn 2021 there has been an extreme drought on the southern side of the Alps. Since then, around 300 millimeters of precipitation have been missing in Lugano compared to the norm in previous years.
According to the current situation report from the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), the current drought has various causes:
- In winter there was precipitation, but often not in the form of snow, but as rain. This has already drained off again, which is currently leading to low discharges and water levels (e.g. at Lago di Lugano).
- Generally below-average discharges in the western part of the Swiss Plateau and north-western Switzerland due to the lack of precipitation. Many areas of Switzerland hardly saw any rain in March and April. In addition, there is a constant wind, which dries out the soil.
- Due to the relatively warm weather early on, the snow cover melted faster everywhere in Switzerland. This leaves the floor unprotected and the moisture in it evaporates faster.
The forecasts from Meteo Schweiz show temperatures for mid to late April that correspond to the long-term average. Models that forecast the hydrological situation (river discharge, lake levels and soil saturation) expect the situation to worsen well into May.
This is because the outlook for the possible development of discharge in the next four weeks for sub-areas in Switzerland shows that low discharge volumes and water levels below the long-term average are expected by mid-May.
The low to no precipitation period began at the end of February. In several places, March and April remained almost completely dry. For example, not a drop of rain fell in Lucerne, Zermatt and Andermatt in March. Rainfall was also very low in Valais. In Sion, there was only 6.5 millimeters of precipitation in March.
Although a brief cold front at the end of March to the beginning of April brought some relief, the amounts of precipitation were modest and therefore could not noticeably ease the situation.
In Ticino, the water deficit is far greater than in the other parts of the country. According to Meteo Schweiz, the southern side of the Alps has been suffering from a lack of precipitation for six months: the last major rainfall was at the end of November. Since then there has been hardly any rain or snow. In March, only 12.4 millimeters of precipitation fell in Lugano, which is around 13 percent of the usual precipitation in the first quarter.
Due to the lack of rain and the strong evaporation in recent weeks, there is a lack of water throughout Switzerland. This was announced by the Federal Office for Meteorology and Climatology (Meteo Schweiz) at the end of March. Up to March 29, the precipitation totals reached only 10 percent of the average March amount (norm 1991-2020). Locally there was no precipitation at all, which means that in certain cantons almost the entire average amount of rain is missing. It takes more than just a short thunderstorm or some rain to balance this out, but very large amounts per square meter to restore the water balance to the soil.
Accordingly, it will take time to correct the water shortage that prevails from the surface of the earth to a depth of two meters. Although a few days with normal amounts of rain are not enough, every rainy day already means an alleviation of the current drought. If the top layer of soil contains enough water, this will at least provide relaxation for smaller plants with shallow roots.
If there is still no precipitation, partial or even general fire bans are very likely. This is to prevent dry leaves, grass, twigs and ultimately entire forest areas from catching fire. Because the risk of fires is as high in spring as in summer. However, there are hardly any natural detonators in spring, such as a lightning strike. When a fire breaks out, it is almost always man-made.
Fires seriously endanger people and animals. On the other hand, they are even good for vegetation, as they form a rich breeding ground for fresh plants. Read more about the origin and threat of forest fires here.
Nevertheless, fires are prevented in Switzerland whenever possible. «We need our forests for protection. Because the trees stabilize the soil with their roots,” explains Marco Conedera, head of the research unit at WSL. The roots of a burned tree can hold the earth and rock, for example on a steep slope, for another five to ten years. It is often only then, and therefore extremely unexpected, that a debris flow occurs.
The summer half of 2018 went down in history as a year of drought. It was the hottest in Switzerland since measurements began. In addition, there was an enormous drought between April and September. It hadn’t rained as little as in 2018 in almost a hundred years.
At that time, the dry late summer and autumn were particularly problematic. However, the precipitation curve can also correct upwards again in the course of the year. However, if the dry spell persists, it could have a much more serious impact on nature than it did four years ago.
As a result, farmers had to slaughter animals in 2018 because the fields with the fodder dried up. In order to water thirsty alpine cows, the Swiss army even flew special missions to provide the animals with water by helicopter.
Many communities turned off the village wells and asked their residents to use water sparingly. Because the groundwater level had dropped drastically in many places. Many small bodies of water also dried up. Large rivers and lakes carried significantly less water.
The general population does not yet have to take any measures to save water. These only have to be considered if the groundwater level drops too much. But that is not the case yet.
Long periods of drought and high temperatures in spring lead to increased pollen flight and increased pollen levels in the air. For allergy sufferers, this usually means more severe symptoms than they are used to from previous years.
The Swiss Allergy Center «aha!» reports a high concentration of birch, beech and oak pollen on both sides of the Alps. This is particularly felt by people affected by spring allergies. But even those who suffer from summer allergies must soon expect symptoms. The grasses are also blooming earlier this year due to the heat. If the grasses bloom earlier, allergy sufferers also suffer: according to “aha!” around 70 percent of all people with hay fever are affected.
The drought currently has advantages and disadvantages for agriculture. This makes various field work easier, and thanks to the dry weather, the bees can fly every day and pollinate flowering fruit and rapeseed crops.
Irrigation installations are common for vegetables of all kinds, new potatoes, fruit and berry crops. These feed, however, mostly from the nearby, small bodies of water. If the water level falls too low, cantons can issue a withdrawal ban in order to protect the ecosystem in the water body. The farmers then only have to irrigate with drinking water, which is associated with great costs.
The most precarious situation is for forage production. It is not financially worth irrigating pastures and grass growing areas. In addition, the fields are not set up for it.
WSL hydrologist Zappa advises anyone who grows their own vegetables in their garden to water the soil well at the moment. Because the first 20 to 30 centimeters of soil dry out quickly despite the brief rainfall. Plants whose roots do not reach deeper run the risk of drying out.
The roots of the trees reach far into the lower layers of the earth. These dry out less quickly than the upper layers of the earth, which are exposed to greater evaporation from the sun and wind.
The drought is changing the forest, especially in the long term. Trees such as spruce, fir and, in some places, beech will gradually disappear from our forests and be replaced by tree species that are better suited to the new conditions. Institutions like the WSL make predictions about what these conditions might look like. Since trees live between 100 and 150 years, you have to plan well in advance. “Our forest is becoming lighter and more airy, since deciduous trees such as oaks and chestnuts in particular can deal better with drought,” predicts Patrik Hofer, Managing Director of the Swiss Forestry Association.
The inhabitants of smaller bodies of water are the first to suffer from a drought. Because these are fed by precipitation and moisture in the soil. If there is no rain, they dry out quickly. “This is particularly problematic for the fish in these waters,” says Urs Tester, Head of the Biotopes and Species Department at Pro Natura.
Amphibians also need moisture and small bodies of water to spawn there. Frogs, toads and newts, for example, have not yet been able to migrate to the water bodies due to the dry soil. They’ll catch up when the rain comes. “In order for their offspring to survive, they depend on the spawning waters not drying out. If they do that, an entire year of frogs can be lost,” says Tester.
Long periods of drought also lead to withered meadows. While grasses and herbs still survive thanks to their roots and seeds, things are different for animals. “It is a bigger problem for animals that live on this plant, such as caterpillars or wild bees. They lack food and die,” explains Tester.
Cooperation: nad./gam./bai./kca.