Estimation of suspendent sediment concentration using acoustic methods

Abstract

Acoustic Doppler current meters (ADCP, ADP, and ADV) can provide information about the suspended sediment concentration (SSC) in the water; although, they are designed for flow velocity measurements. Contrary to conventional samplers, those are labor intensive for measuring SSC, when an acoustic instrument is calibrated for a water system; no additional sensor is needed to measure SSC, enabling the researchers to measure velocity and concentration simultaneously which is required for most sediment transport studies. Recently, the acoustic instruments are investigated in different studies where signal to noise ratio (SNR) and SSC were related using different formulations. However, these studies were limited to single study site where neither the effect of particle size nor the effect of temperature was investigated. In the scope of this study, different parameters that affect the ADV.s performance prediction of SSC were investigated. In order to investigate the reliability of ADV in different environments, SSC measurements were made in different streams. Soil samples were collected from all measuring stations and particle size analysis was conducted. The multivariate data analysis was applied to the measurements to derive a relation formula between SNR and SSC. Multivariate analysis indicated that reported SSC values depended on at least three parameters; water temperature, mean diameter of the soil, and shape of the particle size distribution curve. Also, effect of high SSC conditions on ADV performance was investigated during and after rain events. Results indicated that ADV was not capable of measuring SSC when a limit concentration (SSC>400 mg/l) was exceeded.