Ice fields become glaciers
In the topographical landscape model, this limitation falls away. The digital representation makes it possible to combine various layers along topographical rules. For instance, forest and bodies of water can touch but not overlap. Boulders can lie on top of ice. And liquid water – for instance glacial lakes – can be present over ice. Layers can be added or removed on the computer, producing a comprehensive model of the landscape that is fit for all possible purposes.
Now for the first time, swisstopo’s new landscape model also records glaciers according to glaciological rules. For instance, it is sometimes the case that two glaciers, located on opposite mountain flanks and with opposing directions of flow, will meet along a mountain ridge. From a cartographical viewpoint, this would be treated as a single large area of ice. But from a glaciological viewpoint, these are two “individuals” that have little in common and no effect on each other – apart from where they brush against each other on the mountain ridge.
“In future, glaciers will be given a unique number to make their history traceable,” Weidmann explains, adding, “Should a glacier with two catchments in two different valleys melt to the extent that it becomes two independent glaciers, one of them will be assigned a new number.” These inventory numbers not only make it easier to identify glaciers, they also help to document their history.
A model of unprecedented precision
By linking the inventory to glaciological computational models, researchers can show how much water each glacier will deliver and when.
The more data that flows into the model, the more precise the basis on which to make predictions. As a result, GLAMOS achieves an unprecedented level of precision. Every four to six years, swisstopo aircraft record each square metre of Switzerland. The 3D images generated are capable of showing changes in altitude across a grid of two metres by two metres to an accuracy of some 50 centimetres. If an area of gravel sediment ahead of a glacier snout sinks noticeably between two measurements, there is probably ice under it. The true proportions of the glacier below are better documented with each subsequent measurement.
A treasure trove of data
The first complete inventory of glaciers was drawn up in 1973. Later, a second inventory was reconstructed for the year 1850 based on estimates, maps and moraines. Additional surveys followed in 2000 and 2010. All these inventories were important for research, but each was produced using its own set of rules and different methods, making them barely comparable.
From 2019, Switzerland will for the first time be able to turn to a glacier inventory that will undergo dynamic further development and be completely renewed every four to six years. And the cost of the new glacier inventory is manageable because GLAMOS is drawing on existing troves of data, processing them, interlinking them and making them available in a format that a wide audience can use.