Comparative Assessment of Fluvial Suspended Sediment Concentration Analysis Methods

Abstract

The monitoring of fluvial suspended sediment transport plays an important role in the assessment of morphological processes, river habitats, or many social activities associated with river management. However, establishing and operating a well-functioning sediment monitoring system requires the involvement of advanced indirect methods. This study investigates the advantages and limitations of optical and acoustic devices, to quantify the uncertainties and provide a comprehensive comparative assessment of the investigated indirect methods. The novelty of this study, compared to previous ones, is that four different indirect techniques are parallel tested, i.e., the laser diffraction based LISST-Portable|XR, an infrared based optical instrument, the VELP TB1 turbidimeter, the acoustic based LISST-ABS (Acoustical Backscatter Sensor) sensor, and a 1200 kHz Teledyne RD Instruments Acoustic Doppler Current Profiler (ADCP). The calibration of all the indirect methods was performed based on more than 1000 samples taken from the Hungarian section of the Danube River within a wide suspended sediment concentration range. Implementing a comparative assessment of the different sediment analysis methods, a qualitative and quantitative characterisation of the applicability is provided. Furthermore, a proposal for an optimised sediment monitoring methodology is also suggested.

Characterizing the Composition of Sand and Mud Suspensions in Coastal and Estuarine Environments Using Combined Optical and Acoustic Measurements

“…The attenuation terms ( α s and α w ) are higher at larger concentrations and greater distances (Thorne et al., 1993) but can be neglected below 1,000 mg/L (Chmiel et al., 2018) and O (10 cm) from the sensor (Pomázi & Baranya, 2020). In this study, we thus neglect attenuation, given the small distance between source and measuring volume (15 cm) and low concentrations expected at our study site in Ameland (<1,000 mg/L).…”

Hydrodynamically‐Driven Deposition of Mud in River Systems

“…Using the FlocARAZI, we see the depth-averaged distribution of floc sizes at each station and note an abrupt shift in the floc-size distribution around station SP5B (Figure 3b). Suspended sediment samples were collected using a P6 sampler and were later dosed with sodium hexametaphosphate, sonicated, and analyzed using a LISST-Portable XR (Pomázi & Baranya, 2020) to determine the grain size of the constituent particles of the observed flocs (Figure 3b). The decrease in floc size coincides with both an abrupt increase in salinity of the river water and in the mud content, determined through proportion of silt and clay by mass of the bed sediment (Figures 3c and 3d).…”