The Load-Cell Scour Sensor is sensitive to small changes in
sediment load and can measure infilling of gravel and cobbles with
fine-grained sediment. Ideal uses for the sensor include (1)
shallow placement in spawning beds of fish for unattended
monitoring of deposition, erosion and substrate temperature, (2)
monitoring transport of bedforms in experimental flumes, and (3)
monitoring scour at bridge piers or similar structures.
The load-cell sensor weighs the sediment, water, and air above
it, and an accompanying pore-pressure sensor weighs the water and
air above it. The difference between the two weights is the weight
of the sediment overlying the sensor pair. Combined sensitivity
and repeatability are ±0.01 foot of sediment thickness or less. A
temperature sensor in the pressure-sensor housing provides useful
information about the spawning-bed and sensor environment and
enables calibration of the pressure sensors to ±0.02 percent of
the full-scale output.
The sensor can be buried or jetted into cohesion sediment such
as a sandbar. The deeper the sensor is buried, the safer it is
from being scoured and the larger the area it averages. The
shallower the sensor, the greater the detail that can be
determined from closely spaced sensors, but the greater the risk
of removal by scour.
The sensor also works on its side, with the foil in a vertical
plane, because changes in horizontal stress (with a coefficient of
about 0.3) in sediment accompany changes in vertical stress
(weight per unit area) that are caused by scour and deposition.
The load-cell sensor can provide unattended measurement and
documentation of scour, deposition, and sediment transport in
ephemeral streams. Installation of multiple sensors in two or more
closely spaced cross sections will enable automated slope-area
determinations of discharge and establishment of rating curves at
sites in sand channels that are inaccessible during flow.
Additional uses of the sensor include scour at bridge piers and
similar structures, studies of liquefaction or quicksand, and
The load-cell scour sensor consists of a shallow, stamped 10
inch by 6 inch rectangular stainless steel vessel, and the sensors
are tested to 30 pounds per square inch and can be buried to a
depth of 40 feet. Sensor output cables come in 50 ft. standard
lengths with a 4-20 ma signal to a datalogger.
407-015 Scour Sensor