Author(s): Gordon Gilja; Antonija Harasti; Robert Fliszar

Linked Author(s): Gordon Gilja

Keywords: DCP; Bedload; Danube; Helley-Smith; Sand-bed; Sediment transport

Abstract: Direct bedload samplers are simple and widely used, but obtaining unbiased bedload transport field data has been proven challenging from the perspective of the sampler's orientation relative to the oncoming flow and hydraulic efficiency. Once the sampler is placed on the bottom, its orientation and potential rotation due to the local riverbed shape are unknown, introducing a potential bias in the results. The hydraulic efficiency of a Helley- Smith sampler has been experimentally documented in the past, as well as the influence of misalignment with the flow to sampling where the significant drop in sampling efficiency was observed when the sampler deviates from the mean flow by 10°. This study presents the results of field deployment of a Helley-Smith sampler with a 15.24 cm entrance nozzle on the Danube River, equipped with a 3D tilt and compass sensor, and simultaneous flow velocity data was measured with ADCP RioGrande. The goal of the study is to provide insight into the sampler's movement throughout the water column after release from the boat and subsequent orientation on the riverbed.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0283-cd

Year: 2023