| Summary: | 碩士 === 國立中央大學 === 水文與海洋科學研究所 === 103 === The study aims to investigate the suspended sediment concentration (SSC) for uniform and non-uniform particles using Acoustic Doppler Velocimeter Ocean（ADVO）and Optical Backscatter Sensor（OBS）. Because the backscatter intensity of the transmitted signals from the acoustic and optical sensors varies depending on the SSC in the water, it is possible to find an empirical correlation function between the measured backscatter intensity and the SSC. Because air bubbles and non-uniform distributed SSC in the water can affect the calibration results, we try to exclude these factors in advance to increase the calibration accuracy. We developed a new calibration tank and perform the verification of spatial uniformity, and experimental repeatability. The results show that the calibration tank and the experimental methods can be used to calibrate the SSC.
In this study, artificial uniform glass particles and non-uniform sediment particles sampled from the field over an algal reef are used for calibration. The calibration curves of the optical sensor for the uniform glass particles and field sediment particles are compared; it is found that the backscatter intensity shows a linear trend with the SSC within a specific range of SSC, and then the gradient between the SSC and backscatter decreases when the SSC exceeds the specific value. In addition, the study confirms the linear relationship between the acoustic backscatter intensity and the SSC for a specific SSC which indicating that ADVO could be used to measure the change of SSC in fields. Finally, we compared the results with Ha at el. [2009], and found that the trends of the calibration curves of the ADVs are similar to their results even though different sediment particles are used in the two experiments.
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