From glaciers to large rivers: Lessons and insights from long-term bedload monitoring

Abstract

Quantifying bedload transport and its processes is a key challenge in river research and has been a topic of study for decades. In Austria, bedload transport is continuously monitored at seven sites, ranging from high-altitude Alpine regions to the Danube River, for over one decade. The investigated catchment areas range from 56 km² to 104,177 km². Direct measurement methods, including various bedload samplers, as well as indirect measurement methods, in this case, plate geophones, were used. Thus, the bed load transport of all flood events that occurred during the project period from 2010 to 2021 was recorded. Bedload transport and bedload yield could be determined on a station-specific basis using calibrated plate geophones and if possible, at the monitoring site with the bedload rating curve approach. A total of 2,848 individual measurements were conducted, using various bedload basket samplers, and 49 measurements with slot samplers. The mean annual bedload load at the observed sites ranges from 4,500 t to 360,000 t at the monitored catchment area. However, the annual loads are subject to significant fluctuations, depending on hydrology and catchment size. Long-term monitoring has shown that reliable conclusions can be drawn about bedload transport and its dependence on discharge and anthropogenic influences. The correlation between discharge and bedload transport tends to be weaker in smaller catchments.