BOUNDARY CONDITIONS FOR AN ARTIFICIALLY-TRIGGERED DEBRIS FLOW DEVELOPED IN GLACIAL DEPOSITS

摘要

Thresholds for the stability and initiation of a debris flow were studied at the "Frida"- subcatchment in the Lainbach basin, Northern Limestone Alps, Bavaria. The test site is representative for a steep slope in a cohesive, highly unstable Pleistocene sediment filling in an Alpine valley. The geometry and characteristics of the sediments at the test site were studied geodetically, mechanically, geoelectrically and using georadar. The volume of natural water content was increased by artificial infiltration up to the limit of stability. The critical triggering value for a small debris flow (< 50 m~3) was reached at 16,5 to 18,5% (weight) of soil water. Similar studies on the amount and distribution of precipitation during a wet summer and its interactions with slope stability will further improve our knowledge on the initiation of debris flows.