IOWA SEDIMENT CONCENTRATION MEASURING SYSTEM

Abstract

The Iowa Sediment Concentration Measuring System (ISCMS) is an electro-optical instrument developed in 1969 (Glover, Bhattacharya, and Kennedy 1969) for measurement of suspended solid concentrations in unsteady solid-liquid flows. It has been used extensively in laboratory investigations to determine spatial and temporal variations of sediment concentration in a variety of steady, unsteady, uniform, and nonuniform flows (Bhattacharya 1971; Danushkodi 1974). Concurrent measurements of concentration and velocity fluctuations have been used together to obtain estimates of mass transfers in unsteady sediment-laden flows, with the goal of improving the understanding of the underlying mechanisms responsible for sediment entrainment and suspension (Nakato 1974). Interpretation of the data gathered in these experiments pointed out the need for a more thorough understanding of how the optical and electronic components of the ISCMS respond to the passage of individual sediment particles through the optical field of the transducer (Locher et at. 1974). An investigation was undertaken to determine the sensitivity of the ISCMS output to the position of a particle in the transducer field; the role of particle velocity in determining the ISCMS output; the effects of particle translucency and size on the output of the system; and the dependency of mean concentration estimates on integration time.