UZH researchers prove that the Grand Marais is sinking

01 July 2024 00:16

Swissmem SSIG

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Zurich/Bern - Researchers from the University of Zurich (UZH) have used digital mapping technology to prove that the Grand Marais in the Bernese Seeland region is sinking. Compared with 1920, the terrain has sunk by up to 2.40 meters in some places. The measurements provide information about the required soil restoration efforts.

Researchers from the Department of Geography at the University of Zurich (UZH) have used digital measurement records to confirm that the soil in the Grand Marais in the Seeland region of the canton of Bern has sunk by 2.40 meters over the past century. As detailed in a press release, the team led by Markus Egli und Claudia Röösli compared data that had been manually collected as part of a historical terrain survey with new data from a digital terrain model created by the Federal Office of Topography.

In a first step, the 44,000 survey points of the regional map, which was created manually in 1920, were digitized. The data collected in this way was then compared against current terrain data, obtained via a terrestrial application of LiDAR - a measurement system that functions on the basis of laser technology - or from aircraft, among other aspects. The comparison of the historical data set with the current one reveals not only that the Bernese Seeland has sunk overall, but also where the deepest sink points have occurred.

The researchers believe that one of the main causes behind the sinking of the peat soil is the fact that the area is used extensively for agricultural purposes. In fact, the Grand Marais region is also known as the vegetable garden of Switzerland. The agricultural use of the land also led to intensive drainage of the terrain, with the consequences of this having now been identified. The maps of the Grand Marais drawn up by the UZH researchers show where soil restoration efforts will be required in the next future and where a switch to sustainable, environmentally friendly agriculture should be made. ce/ww


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