Evaluation of Pressure Transducers under Turbid Natural Waters

Abstract Pressure measurements made in two turbid natural waters have led to the inference that the effective depth-mean in situ density values, ρeff, of these waters are less than (≈2.70%–6.5%) their bulk densities (i.e., densities of water–sediment mixture), and also less than (≈0.4%–4.5%) that of the density of the same water after removal of suspended sediment. The values of ρeff in a given site differed from one tidal cycle to another (≈1.9%). These values varied slightly (<0.8%) from midtide to slack water period of the same tidal cycle, with ρeff being lower at midtide. It was found that the use of bulk density to estimate tidal elevation yielded an underestimation of tidal range (up to 7%). The underestimation has been corrected (to within ±1.5%) with the use of ρeff parameter. For clear waters there was no measurable underestimation in tidal range. The observations indicate an apparent in situ density reduction for turbid natural waters. With the use of two pressure transducers at a known vertica...