Sediment transport in an alpine river before and after a dambreak flood event

摘要

Fluvial sediment transport in the high mountain Partnach River (Reintal Valley, Bavarian Alps) was investigated during a 10-year observation period (2001-2010). During this period, the downstream reach of the Partnach River was decoupled from upstream sediment throughput by a rockslide deposit until 2005. In August 2005, the dam was partially breached during a flood event resulting in renewed sediment coupling between the upstream and downstream reaches. A comparison of pre- and post-dambreak river sediment load data showed that the dissolved load dominated sediment transport prior to August 2005 with a switch to the dominance of bedload transport, post-dambreak. The higher post-dambreak bedload rates were particularly evident during the first years after the dam failure due to significant coarse material coupling between active sediment sources (undercut banks/talus cones) and the Partnach River. In the last years of the observation period (2009 and 2010) the dominance of dissolved load transport was re-established.