Dynamic slope processes in Variscian mid-mountains: today and the past on the example of the Sudetes Mts
Abstrakt
Geomorphological history of the Sudetes Mts. (NE part of the Bohemian Massif), as an example of a typical Variscian mid-mountain range, has been affected by tectonic, fluvial, glacial and periglacial agents. Present geomorphological and environmental state of the mountain range is a result of all the above-mentioned phenomena, but dynamic mass movements still have significant role in the mountains, even when they consist of relatively consolidated metamorphic rocks.
The impact debris flows and snow avalanches has been studied using multiple approaches in the eastern part of the High Sudetes Mts. As the both processes usually occur repeatedly in the same paths, the spatial distribution of the paths and the frequency of the events need to be examined.
Field geomorphological mapping, analysis of very detailed LiDAR digital elevation models and written sources have been employed to collect spatial data representing avalanche and debris flow paths and debris flow accumulations. Moreover, to reconstruct the recent activity of the processes, dendrogeomorphological sampling has been applied in selected localities.
The validity of the laboratory results was underlined and supported by other data from the last century, such as the written sources, dated aerial photographs or meteorological data, yet there has been no comprehensive study about avalanche and debris flow chronology in the area published. The relicts of old debris flow accumulation deposits have been dated using luminescence method.
As a result, we have mapped and morphometrically evaluated 95 recent debris flow paths with potential reactivation, 47 accumulations of Pleistocene high-magnitude debris flows and 5 active snow avalanche areas in the eastern part of the High Sudetes. The recent frequency of the processes is usually measured in tens of years, which means they are less active than in alpine environment.
Nevertheless, they had very significant morphological role in the past and they still have significant impact in geomorphology, forestry, ecology and infrastructure in the present time. Detailed information on their behavior is useful for the forest, nature reserve and infrastructure managements as well as for scientists from multiple disciplines.
This work was supported by the Charles University Grant Agency under the project "GAUK 1072116: The Geomorphic Evolution of the Upper Parts of Valleys in the Eastern High Sudetes Mts. in the Holocene". The Jeseníky Protected Landscape Area is acknowledged for the permission of fieldwork in the area.