Schwebstoffmonitoring an österreichischen Fließgewässern unter Anwendung moderner Messtechnik

Sediment management in fluvial systems is gaining importance due to associated technical, economic and ecological problems. Appropriate management and modelling relies heavily on high quality input and calibration data. Due to a lack of a proper monitoring strategy the Austrian hydrological survey decided to design and implement a new monitoring program. This dissertation describes the development of such a measurement and analysis concept which is strongly based on the knowledge of the ongoing fluvial processes. The preliminary concept has been implemented and tested at several gauging stations all over Austria representing all major types of rivers. Both, gravimetric and surrogate measuring technologies are applied for monitoring the temporal and spatial variability in suspended sediment transport. Optical sensors record the changes of the river-turbidity with high temporal resolution. These turbidity data are calibrated by means of bottle samples and converted to suspended sediment concentrations using empirical equations or conversion factors. Due to the spatial variability, the cross-sectional mean sediment concentration is measured by selected point sampling at different discharges during the year. Based on these datasets cross-section factors are delineated and applied to the time series. The obtained results have shown, that the suggested approach adequately measures the suspended sediment transport in Austrian rivers and additionally provides deeper insights in the fluvial processes. ADCP data, which are routinely collected for discharge measurements, build the basis for advances in the development of an optimized suspended sediment monitoring system. The selected monitoring strategy is also embedded in a scaling system which provides a broader view on the gathered information.