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Where is there (no) snow? Satellites record the snow cover on hiking trails

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Active recreation in natural surroundings, like hiking or mountain biking, is widely advertised by tourist offices in mountain regions and outdoor platforms on the Internet. But these activities are very dependent on the weather and terrain conditions. Hiking trails in the mountains are often snow-covered, even in summer. However, it is not always easy to get information about where exactly there is snow and how deep it is as the paths in alpine terrain are often difficult to reach. Checking on the conditions there on foot or by helicopter is very costly.

Therefore, only selected routes are checked from time to time. For example, those responsible for tourism often lack the information they need to assess the condition of hiking trails and advertise them accordingly.


The start-up company, WeGaw, together with SLF, plans to fill this niche with the support of the Euro­pean Space Agency ESA. For its “DeFrost” demonstration project, the young company is using various optical satellites to obtain up-to-date information about the snow cover on mountain trails and to display it on a map. The latest SLF Avalanche Bul­letin and the snow depths recorded by measuring stations in the Swiss Alps provide additional information.

The SLF researchers are using automatic cameras to check whether the new method works. The cameras are installed at several sites in the Dischma valley near Davos. They record, at a high spatial and temporal resolution, where the ground is really still covered with snow. A com­parison of the images with the map shows how well it represents reality.

In DeFrost, it is planned to develop a ‘snow cover index’ for the paths in alpine terrain. The entire system is expected to be in operation by spring 2020. It should help tourist organisations to assess the walkability of hiking trails better.
(Sara Niedermann, Diagonal 2/19)