Ambient suspended sediment concentration and turbidity levels

The temporal variation of suspended sediment concentration and
turbidity is an important component of the riverine environment. 
The maximum rate of discrete volumetric sample collection for
laboratory determination of sediment concentration is one sample
per minute for our field data collection on the effects of
navigation on the Upper Mississippi River System.  In an effort to
obtain truly continuous measurements, another set of intakes and
pumpers was used to obtain and record continuous turbidity data
while discrete samples were being collected.  Ambient suspended
sediment concentration samples and turbidity values were collected
continuously for a three-hour period to measure variability over
time.  A turbidity-concentration correlation was also developed
and used to estimate sediment concentrations for a point at which
only turbidity was measured.  Exponential decay curves were fitted
to each of the three data sets.  A regression equation between the
turbidity and sediment concentration at one level was used to
generate estimated sediment concentrations from the turbidity
values at another level.  Graphical and statistical
characteristics of the continuous ambient data are presented and
compared with the more common ambient measurements taken every few
hours during a day of field data collection.  This unique data set
from the Illinois River illustrates the range of suspended
sediment concentrations over a several-hour period during steady
flow conditions.