Acoustic based assessment of cross-sectional concentration inhomogeneity at a suspended sediment monitoring station in a large river

Abstract

Establishing and operating a harmonized sediment monitoring system along large rivers such as the Danube River is a challenging international task. As an element of such a system, a new monitoring site with state-of-the-art instrumentation is currently under development in the Upper-Hungarian section of the Danube River. The monitoring station will consist of a near-bank optical backscatter sensor and a horizontal acoustic Doppler current profiler (H-ADCP). As previous studies showed, the suspended sediment concentration (SSC) that is continuously measured with near-bank sensors can significantly enhance the temporal resolution of sediment transport monitoring. However, sediment plumes from tributary inflows upstream of the monitoring station can alter the detected near-bank concentrations, eventually biasing the sediment load estimation. Such an influence is likely in the cross-section of the planned monitoring station, therefore, a thorough preliminary analysis of the cross-sectional variation of the SSC was performed, based on expeditionary sediment measurement campaigns. Between 2018 and 2021 24 campaigns were carried out at different hydrological regimes, where physical sediment samplings together with fixed and moving boat ADCP measurements were performed. The cross-sectional variability of SSC and its influence on the sediment load estimations were assessed based on the moving boat ADCP measurements, after calibrating the backscatter signal with more than 500 physical samples. Based on the results, we identified different cross-sectional patterns of the SSC which is apparently governed by: (i) the actual hydrological situation considering both the main river and the tributary, and (ii) the local river morphology. Based on our findings, we suggested a correction method that accounts for the above effects, using which the near-bank SSC can be reliably converted into total suspended sediment load.

Application of Acoustic Doppler Current Profile (ADCP) to Estimate Suspended Solid Concentration (SSC) During the Tidal Phase, Case Study: Donggala, Palu.

“…The vertical distribution of SSCs increased in concentration with increasing depth, the two SSCs acquired in different ways, carried out at the same time [10][6] (SSC obs and SSC adcp ) showed the same distribution pattern. Figure 8 shows the similarity of the same profiling pattern, getting stronger in the lower layers.…”

“…The current are able to move SSC particles to other places, making the backscatter (amp. Sign on counts) on recorded vary temporally [10] and spatial [7]. The object of this study is to identify the relationship between the intensity of scattering values to estimate SSC, and to compare SSC temporally in the tidal phase.…”

Advances in characterizing and monitoring land cover/use and associated ecosystem changes using remote sensing data

“…Such a curve can show how stream flow affects the rate of sediment movement (Assfaw, 2020;Tilahun et al, 2023), but its reliability highly depends on the available dataset. Moreover, because of the difficulties in measuring sediment transport in high-flow conditions, generally, sediment rating curves are generally more reliable for low to medium flows (Sadeghi and Saeidi, 2010;Tomkins, 2014;Pomázi and Baranya, 2022).…”

SWAT model-based quantification of the impact of land use land cover change on sediment yield in the Fincha watershed, Ethiopia

“…Such a curve can show how stream flow affects the rate of sediment movement (Assfaw, 2020;Tilahun et al, 2023), but its reliability highly depends on the available dataset. Moreover, because of the difficulties in measuring sediment transport in high-flow conditions, generally, sediment rating curves are generally more reliable for low to medium flows (Sadeghi and Saeidi, 2010;Tomkins, 2014;Pomázi and Baranya, 2022).…”