Estimation of Suspended Sediment Concentration by Using Mobile ADCP Instrument

Abstract

The measurement of suspended sediment concentration (SSC) by using Acoustic Doppler Current Profiler (ADCP) instrument still not widely used in Indonesia. The application of this technology uses sound wave by four direction transducers placed in the vessel, and this ADCP measured the intensity of backscatter from sediment particles. This study is equipped with RD Instruments WorkHorse Mariner 307.2 kHz ADCP, and the water sample collected from Lembeh Strait, North Sulawesi by using van Dorn bottle sampler. Beyond the experimental purpose of this installation, the interest in having wide area data at different tidal condition is that it provides the possibility of determining the effect of tidal to the SSC. The losses of sound signal were corrected to get more accurate results. Simple linear regression analysis performed to obtain the estimates of the SSC. Estimation of SSC of ADCP measurement was then compared with SSC on water analysis in the laboratory, and the result showed that insignificantly different by statistical analysis. From this research, it showed that the concentration of suspended sediment ranged between 60-73 mg L−1 on location near the Port of Bitung, and 50-62 mg L−1 at a location away from the port. The result also observed that the highest concentration is in the region below the water column, and tidal condition was affected the condition of SSC. Based on all analysis, the mobile ADCP can provide a suitable measurement of suspended sediment concentration.