Assessment of flow field and sediment flux at alpine desanding facilities

Abstract

This paper deals with flow field and sediment flux measurements at alpine desanding facilities. 3D flow velocities and turbidity were recorded and water samples were taken at three alpine desanding facilities. The samples were evaluated regarding suspended sediment concentration (SSC) and particle size distribution (PSD) in the laboratory. SSC was correlated with turbidity and reliable correlations were found for two facilities. The applied instrumentation and methods proved to be appropriate to assess flow field and sediment fluxes. The results show that the flow field is inhomogeneous in large parts of the basins and that the presence of tranquilizing racks has a strong influence on the flow. PSD revealed a refinement of the mean particle size in streamwise direction. The mass-related trapping efficiency of the desanding facilities was estimated based on calculated sediment fluxes and compared to two different trapping efficiency definitions. The results are briefly compared with a current design guideline.