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Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
Extreme temperatures in mountain streams and rivers harm people, nature and the economy. SLF scientist Maria Grundmann is researching how they occur. Her findings should help to develop countermeasures.
It is early on a summer's morning in late July. The Dischma Valley near Davos is still in shadow. A few cows look on with interest as Maria Grundmann leaves the official hiking trail at an altitude of around 2,200 metres above sea level and clambers down a slope to the Furggabach stream. She makes her way towards a large rock in the stream to which she has attached a sensor.
Grundmann is an environmental engineer at the WSL Institute for Snow and Avalanche Research (SLF). She is investigating the factors influencing the temperature of mountain streams and rivers, and how heatwaves develop in them. Such heatwaves not only have a negative impact on plants and animals in the water, but also adversely affect humans. Grundmann wants to better understand why some rivers experience extreme temperatures more frequently than others: "By understanding how high water temperatures come about, we can look for ways to protect our streams and rivers from them."
Fishers, industry and energy suppliers facing problems
Grundmann's sensor sits inside a long tube that she has screwed to the rock. She measures the current water level using a folding rule, then grabs a pen and paper and notes down the value in a table. At the same time, she also works out the water level by calculating it using the water pressure recorded by the sensor. This is important because the volume of water currently in the stream influences how it responds to changes in air temperature.
Her work is part of a wider project investigating riverine heatwaves across Europe. "Water temperatures are rising worldwide due to climate change," says Grundmann. Fish are suffering, catches are declining and water quality is falling, while industry and energy suppliers are also facing problems. If the water in a river gets too warm, they are no longer allowed to discharge heated cooling water, to avoid placing further pressure on the ecosystem. In the worst-case scenario, production comes to a standstill.
The effects of climate change are being felt more strongly in mountainous regions than in lowland areas, with relatively small watercourses more sensitive to rising air temperatures. On the other hand, water in the mountains is cooled by meltwater from snow and glaciers. "Our objective is to find out how strongly and how far downstream this meltwater cooling effect can be measured," explains Grundmann.
15 sensors throughout the valley
The environmental engineer points towards the head of the valley to a mountain called Piz Grialetsch, where three small remnants of the once mighty Scaletta Glacier are clinging on. In 1895, the glacier extended over 500 metres further into the valley. Despite it being midsummer, there is a fresh layer of snow on the neighbouring peaks. In the upper reaches of the stream itself, the snow does not usually disappear until late May. This is a relevant factor for the measurements, as the snowmelt cools the upper parts of the stream in spring.
Grundmann removes her sensor from the tube, takes a laptop out of her rucksack and connects the two with a cable, allowing her to read pressure and water temperature data from the sensor's memory. The data also tells her about the volume of water flowing in the stream. She has installed 15 such sensors along the entire length of the valley. This is what sets her work apart from other projects. "Usually, there's only one measuring station per river or stream to monitor the water temperatures, and often only daily averages are published. We're taking a more in-depth look and also analysing the extreme temperatures during the day across the whole valley." She is therefore measuring the air temperature and using this to draw conclusions about the influence of groundwater, solar radiation and wind. She will continue taking measurements until 2027, but initial results are expected to be available in 2026.
Firmly fixed to the rock
Grundmann is not the first to collect such data in the Dischma Valley. She points down the valley towards Davos. In this direction, near Teufi, the Federal Office for the Environment (FOEN) has been measuring the water temperature since 2003. "I need that data to know what's normal for the long-term average and what the short-term deviations are," she says.
By now the sun has risen over the peaks. The first groups of hikers are out and about. It looks set to be a hot summer's day. Grundmann replaces the sensor inside the tube before heading back to her desk at the SLF. She takes a last look behind her. The stream is babbling idyllically. That isn't always the case, though. Snowmelt and heavy rainfall in particular cause it to swell, which is why she has fixed the metal tube firmly to the rock with large screws. "My measuring stations have to be able to withstand flooding and the bed load it brings with it." Are they secure enough? Grundmann laughs: "I hope so."
Maria Grundmann
PhD student
Snow and Atmosphere
Hydrology & Climate Impacts in Mountain Regions
maria.grundmann@slf.ch
+41 81 4170 381
https://www.slf.ch/en/news/by-a-mountain-stream-with-folding-rule-and-laptop/ to the website
SLF researcher Maria Grundmann regularly treks up to the Dischma Valley to read the data measured by ...
Quelle: Jochen Bettzieche
Copyright: SLF
The researcher measures the current water level with a folding rule.
Quelle: Jochen Bettzieche
Copyright: SLF
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Meer / Klima, Umwelt / Ökologie
überregional
Forschungsprojekte
Englisch
SLF researcher Maria Grundmann regularly treks up to the Dischma Valley to read the data measured by ...
Quelle: Jochen Bettzieche
Copyright: SLF
The researcher measures the current water level with a folding rule.
Quelle: Jochen Bettzieche
Copyright: SLF
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