The geomorphodiversity index map of Switzerland

Quantitative methods to define the geomorphodiversity, the variety of landforms and surface features in a given area, are a promising approach in order to obtain an objective and reproducible working method, adopted by several scholars in a few different variants (Benito-Calvo et al., 2009; Melelli et al., 2017; Burnelli et al., 2023). The geomorphodiversity index of Italy by Burnelli et al. (2023) considers four input parameters: lithology (geological factor), slope angle and geomorphons landforms (topographic and geomorphological factors, Jasiewicz & Stepinski, 2013), and drainage density (as a corrective parameter for flat areas).

Here we focus on Switzerland that, despite its limited area, has diverse and impressive geomorphological features (Reynard, 2021). The main physiographic units (60% of the country) are the Alps, interspersed with deep valleys, such as the Rhone, Rhine, Ticino and Engadine valleys. Past and present glaciers have played a significant role in shaping the landscape. The Swiss Plateau is between the Jura Mountains to the northwest and the Alps to the south; it comprises the relatively flat and hilly lowlands of the country. The Jura Mountains, located to the northwest of Switzerland, are a lower mountain range compared to the Alps characterized by rolling hills and limestone formations, with numerous karst landforms as caves, sinkholes, and underground rivers. Lakes are a meaningful geographic feature in Switzerland, where large and small lakes are the result of glacial activity and intense fluvial erosion during the Miocene, related to the “Messinian salinity crisis” in the southern Alpine valleys. Lakes do not contribute to geomorphodiversity, in the proposed approach.

We obtain a geomorphodiversity index for Switzerland using the same approach and inputs proposed by Burnelli et al., (2023). The basics of the method are calculating the variety of the four input raster maps in GIS, with a moving window approach, casting them into five classes of variety, and combining them into a final, geomorphodiversity raster map. In addition to previous work, we consider different weights for each partial variety map, when performing the combination into the final index. This allows extra flexibility in reproducing the diversity of landforms in the different geomorphological settings of Switzerland. The map by Annaheim (1975) classifies Swiss geomorphological landscapes according to four main genetic processes (glacial, fluvial, karst, and gravitational - denudativ, in German). The weight of each parameter is different for each geomorphological unit, improving the original method, in which all of the factors had the same importance for the final index map.

This is the first Swiss geomorphodiversity map, representing a potentially valuable document for land management. It contains relevant information for biodiversity conservation and natural resource management, as well as geoheritage selection and management, and geotourism.

References

Annaheim (1975) (ed.). Geomorphologie I. Übersicht. Wabern, Atlas der Schweiz Eidgenössische Landestopographie, Plate 8.

Benito-Calvo et al, Earth Surf Proc Land (2009) https://doi.org/10.1002/esp.1840

Burnelli et al., Earth Surf Proc Land (2023) https://doi.org/10.1002/esp.5679

Jasiewicz et al., Geomorphology (2013) https://doi.org/10.1016/j.geomorph.2012.11.005.

Melelli et al., Sci Tot Env (2017) https://doi.org/10.1016/j.scitotenv.2017.01.101

Reynard (2021) (ed.). Landscapes and Landforms of Switzerland. https://doi.org/10.1007/978-3-030-43203-4