An Electro-Optical System for Measurement of Mean and Statistical Properties of Sediment Suspensions

摘要

A new electro-optical system has been developed for in situ measurement of suspended sediment concentration in alluvial channel flows, estuaries, and shoaling waves. The transducer for the system consists of a gallium arsenide diode as a light source and a silicon planer diode as a light sensor. The source light detected by the sensor is modulated by the suspended-sediment in the gap between the source and sensor. The amplifier for the sensor output has been combined on one chassis with signal analyzing circuitry, which includes an analog-to-frequency converter and multiplier circuits. The resulting system is capable of measuring suspended sediment concentrations down to 100 ppm, and can compute the mean concentration, the mean square of the concentration fluctuations, and the correlation between sediment concentration and another signal supplied to the system. Exploratory experiments were undertaken in a recirculating laboratory flume and a laboratory wave basin to evaluate the practical usefulness of the system. (Author)