Quantification of bedload transport in the Hungarian Danube using multiple analysis methods

While bedload transport is crucial to river morphodynamics, quantifying it in large rivers, such as the Danube, poses significant challenges. The current study focuses on the gravel-dominated section of the Danube River in Hungary, where multiple methods have been concurrently applied to evaluate bedload transport. In a representative cross section of the river, the following methods were applied: (i) point-wise direct physical sampling using a BfG-type pressure difference sampler, quality controlled with a video camera mounted on the sampler; (ii) indirect acoustic-based analysis with an Acoustic Doppler Current Profiler (ADCP), evaluating the Bottom Tracking signal; and (iii) indirect acoustic and imaging-based method utilizing Acoustic Mapping Velocimetry (AMV). The ADCP method is calibrated using results from the physical sampling, while the AMV method relies on bedform tracking and is entirely independent from the two other techniques. The results from a series of measurement campaigns, covering a wide range of flow regimes, suggest a robust bedload rating curve for the study section, enabling the estimation of bedload yields and its relation to morphological changes. In addition, the applicability conditions of the implemented methods are discussed.