Hydrology and geomorphic effects of a high-magnitude flood in an alpine river

Kurzfassung/Abstract

The catchment of the River Partnach, a torrent situated in a glacial valley in the Northern Calcareous Alps of Bavaria/Germany, was affected by a high-magnitude flood caused by a long period of intense rainfall. During this event, a landslide dam, which previously held a small lake, failed. The flood wave originating from the breaching dam transported a large amount of sediment derived from bank erosion and the massive undercutting of a talus cone. Using terrestrial surveying and aereal photos, erosional and depositional consequences of the event were mapped, pre- and post-event surfaces were compared, and the sediment budget of the event was calculated for ten consecutive channel reaches downstream of the former lake. According to the calculations of the sediment budget, more than 100000 t of sediment were eroded, 75% of this amount was re-deposited within the study area. In addition, this paper includes a discussion of hydrological characteristics of the event and mapping results for large woody debris and channel dislocations.