Dynamic slope processes in the mid-mountain area of the Central Europe - an example from the Eastern High Sudetes
Abstract
The Eastern High Sudetes laying on the border between the Czech Republic and Poland are a mid-mountain zone with presence of alpine phenomena such as relicts of glaciation, active and relict periglacial landforms, alpine timberline and deep-seated valleys. The mountain range is built of relatively durable variscian metamorphic rock, thus the type and intensity of slope processes affecting the surface morphology is quite different than in less durable flysch mountains (for example the flysch belt of Carpathians, where deep landslides prevail).
In present time, debris flows and snow avalanches are the most dynamic processes affecting the surface of the Eastern High Sudetes. Their activity is influenced by climatological, morphological and lithological conditions, when the average annual precipitation exceed 1000 mm and the steep slopes are covered by thick weathering mantle developed during the Pleistocene glaciation cycles.
This is why the debris flow paths and avalanche paths are located predominantly in the upper valley parts, frequently affected by nivation or glaciation in the past. Debris flow and avalanche activity has implications on the surface morphology among thousands of years and designate ecological factor, forest management disturbances and natural hazard even in present times.
The vegetation cover of the mountains has changed a lot since the 19th century, when the natural mixed forests have been replaced by the Norway spruce (Picea abies) monocultures and non-native dwarf pines (Pinus mugo) were planted above the timberline in order to protect the slopes against erosion. During last centuries, the complex assessment of debris flows and avalanches in the Eastern High Sudetes has not been done, even when the debris flows and avalanches are the most dynamic geomorphologic processes in this area at present time.
Their activity corresponds to repeating events and shows variability of the environment related to climate change and human activity.