Depth maps for selected lakes

Switzerland’s many lakes are a major feature of its landscape. Many of these bodies of water owe their existence to Switzerland’s topography; in particular, the lakes in the Swiss Plateau formed during the various phases of glaciation and the shifting and depositing of loose rock associated with it. The countless dams and reservoirs in mountainous areas, some of which also hold enormous quantities of water, are just as much of a defining feature as the natural lakes in the Swiss Plateau.

Depth maps make it possible to explore parts of the landscape that are underwater, making it possible to access interesting details of the Swiss landscape that would normally only be visible to divers. Examples of this include the courses of prehistoric rivers (Lake Geneva, Lake Constance), terminal moraines from glaciers that retreated millennia ago (Lake Lucerne), clearly visible abrasion marks left behind by glaciers (Lake Constance, Lake Geneva) or the small craters on the floor of Lake Neuchâtel, which were formed by water escaping from subterranean sources.

Some of the lakes are impressively deep, but even these depths can be explored with the aid of 3D mapping models. With a maximum depth of 310m, the deepest lake in Switzerland is Lake Geneva. The deepest lake located entirely in Switzerland is Lake Brienz, which bottoms out at a depth of 261m, while the deepest artificial lake in Switzerland is Grande Dixence Dam in Valais, with a maximum depth of 227m. Although Lake Maggiore is even deeper than Lake Geneva at 372m, its deepest point falls outside of Switzerland’s borders.

Bathymetric surveys have been conducted on more than twelve lakes in Switzerland as part of collaborative projects with cantons, universities, the Swiss Federal Government and public institutions from neighbouring countries, producing precise maps of the surface of the lakebeds. However, for technical reasons, these data were mostly only collected for deeper lakes. In more level areas and for lakes for which no bathymetric data is available, the depth of lakes was calculated using depth contours from Swisstopo maps. These inference-based elevation models do not quite offer the same degree of precision, and consequently do not present an accurate picture of the lakebeds. However, they do make it possible to indicate lake depth, and provide an approximate idea of the lay of the lake’s terrain.