Hydrogeomorphological characteristics and fluvial sediment transport of a high mountain river (Reintal Valley, Bavarian Alps, Germany)

摘要

Detailed hydrogeomorphological investigations in a 2.1 km channel reach of the Partnach River in the Reintal Valley in the Bavarian Alps were carried out during a pre-event equilibrium state of the river system. Hydraulic parameters were derived from multitemporal surveying of the longitudinal profile and channel cross sections. Grain size analyses were carried out on seven selected sites using the photo sieving approach. The photographs were taken with a newly developed tethered balloon system. In the Partnach River various strong dependencies between geometrical and hydraulic parameters were determined empirically. The Partnach River showed an increase in channel width and depth with increasing distance downstream. Average velocity, specific stream power and bed shear stress decreased downstream. Furthermore, there are clear relations between bed shear stress, specific stream power, channel gradient and grain size. Downstream fining of the riverbed sediments was obvious, but interrupted by lateral sediment supply by debris flows. In the field season 2004 the fluvial sediment transport of the Partnach River was dominated by solute load, due to prevailing lithology in the catchment (limestone) and the decoupling of large parts of the drainage area in terms of fluvial solid load transport. Yet in 2004 after debris flow events in the preceding year more bed load was transported compared with previous observations.