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Federal Office of Topography swisstopo
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Our boundaries move

Boundaries are commonly regarded as stationary. Depending on the terrain, however, they are subject to climatological changes and natural phenomena and may thus change their course.

Topographic map (Enlargement in new window)Enlargement in new window
Topographic map
Aerial photograph (Enlargement in new window)Enlargement in new window
Aerial photograph
Graphic representation of how a glacier melts (Enlargement in new window)Enlargement in new window
Graphic representation of how a glacier melts

Glaciers

The water divides above 3'500 m traversing perpetual snowfields and glaciers have shifted during the past decades, partly due to melting glaciers. The following aerial photograph and topographic map show the boundary between Switzerland and Italy at the Furggsattel in Zermatt. The crosses depict the boundary in 1940 and the new course is shown in red.

The graphic representation illustrates how the courses of boundaries around Zermatt are influenced by melting glaciers. From 1940 to 2000, the height of the glacier has decreased and the water divide now follows the rocks. This decrease causes a shift in the boundary of about 100 to 150 m.

Only approx. 40 km of the water divides between Switzerland and Italy (total length 578 km) traverse snow fields or glaciers. There are no snow fields or glaciers along the rest of the alpine boundaries between France and between Austria which might result in any modifications. The entire boundary passes across solid terrain.

From the point of view of the geometer, these boundary modifications are due to natural phenomena which must be taken into account in order to guarantee the correct revision and update of our topographic and cartographic products. However, it is not possible to make new surveys every few years; therefore, such updates are only carried out as the need arises.

 

The Inn River marks the boundary between Austria and Switzerland (Enlargement in new window)Enlargement in new window
The Inn River marks the boundary between Austria and Switzerland.

Rivers and streams

The boundary between the Canton of Geneva and France has a total length of 103 km, of which 50 km pass through the middle of rivers. Through the decades and because of flooding, these rivers have also changed their course. Surveys show that in various places these boundary modifications involve several meters, some of which are private property.

The same situation is true for the Doubs River which forms the boundary between France and the Cantons of Neuchatel and Jura. As long as these rivers are not contained in channels, the boundaries will follow their natural course. Here again, nature decides and we can only accept these natural modifications.

 

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