Quantification and Analysis of Suspended Sediments Concentration Using Mobile and Static Acoustic Doppler Current Profiler Instruments

Abstract

The application of Acoustic Doppler Current Profiler (ADCP) can be used not only for measuring ocean currents, but also for quantifying suspended sediment concentrations (SSC) from acoustic backscatter strength based on sonar principle. Suspended sediment has long been recognized as the largest sources of sea contaminant and must be considered as one of the important parameters in water quality of seawater. This research was to determine SSC from measured acoustic backscattered intensity of static and mobile ADCP. In this study, vertically mounted 400 kHz and 750 kHz static ADCP were deployed in Lembeh Strait, North Sulawesi. A mobile ADCP 307.2 kHz was also mounted on the boat and moved to the predefined cross-section, accordingly. The linear regression analysis of echo intensity measured by ADCP and by direct measurement methods showed that ADCP is a reliable method to measure SSC with correlation coefficient ( ) 0.92. Higher SSC was observed in low water compared to that in high water and near port area compared to those in observed areas. All of this analysis showed that the combination of static and mobile ADCP methods produces reasonably good spatial and temporal data of SSC.

Prediction and classification of suspended sediment and zooplankton signals from acoustic Doppler current profiler backscatter data using artificial neural networks

“…Analysis using ANN required data to be selected with linear forms such as suspended sediment concentration (mg l -1 ) from previous research [1] and abundance of zooplankton (ind m -3 ) which was calculated by the relationship between MVBS and TS values [14]. Using linear forms, the data from the training carried out on logarithmic data (dB) from MVBS and RB obtained a small correlation coefficient (r), around 0.1.…”

“…However, these techniques, in addition to being time-consuming, may result in low accuracy. The other limitation is that the results' linearity level with environmental conditions remains unknown [1]. The accuracy of the processing results also has limitations for prediction in the future.…”

Variation of Zooplankton Mean Volume Backscattering Strength from Moored and Mobile ADCP Instruments for Diel Vertical Migration Observation

“…ADCP instruments have significant advantages in detecting zooplankton because of their wide coverage area of three or four transducers [27]. The consistency of the backscatter value from each transducer was analyzed by using cross-beam calibration [17,20]. Aside from that, the acoustic waves from ADCP instruments still have sound attenuation from the geometrical spreading and sound absorption in the water column.…”

“…However, from the previous research, although the observation was simultaneous, it was reported that the precision of the backscattered signal measured by ADCP has a limitation in measuring and detecting different types of scatterers, for example, bubbles, zooplankton, and suspended sediments which individually and differentially affect the acoustic backscatter signal [18][19][20]. On the other hand, the use of single frequency acoustic in ADCP, in particular, is hardly able to discriminate the scatterers [21] and difficult to use to observe the zooplankton presence [9,22].…”

Kehadiran Gelombang Soliter dan Transpor Sesaat Sedimen tersuspensi di Perairan Pantai Bengkulu Tengah

“…Sinyal akustik ADCP yang berupa intensitas gema dalam satuan count setelah dikonversi ke dalam satuan desibel (dB) digunakan untuk mengidentifikasi tingkat kekeruhan. Satu count setara dengan 0,43 dB pada RD Instruments (Dwinovantyo et al, 2017).…”