ABSTRACT
Real-time measurements of suspended sediment mass concentration (SSC) and particle size distribution (PSD) are of importance to improve the understanding and management of many fine-sediment related processes. In the field study at the HPP Fieschertal in the Swiss Alps, a turbidimeter, a Laser In-Situ Scattering and Transmissometry instrument (LISST), a Coriolis Flow and Density Meter (CFDM), and an automatic bottle sampler were used to continuously measure SSC and PSD. The performance of the instruments was assessed based on the measurements conducted in 2013 and 2014. While the SSC measuring range of the LISST with an optical path length of 5 mm (without dilution) was confirmed to be limited to about 1.5 g/l of medium silt, the CFDM allowed measuring higher SSCs of up to 13 g/l. In this paper, the measuring techniques, instruments, setup, methods for data treatment and selected results are presented. The combined use of a standard LISST instrument and a CFDM, supported by automatic bottle sampling, is recommended to measure a wide range of SSCs in silt-laden waters with relatively low uncertainty and cost.
