4
Sediment Trapping and
Dredging Systems
Introduction
This chapter describes the design, testing, and verification of the sediment
trapping and dredging systems developed for the LSTF. This system is used to
measure the magnitude and cross-shore distribution of sand transported along the
beach while waves and currents are generated. This system is comprised of the
following components:
a. Twenty gravity-feed rectangular sediment traps and the associated
support frames.
b. Sixty individual load cells (three for each trap) to obtain real-time
measurements of the quantity of sand that accumulates in each trap.
c. A data acquisition system for data collection and real-time display of the
quantity of sand simultaneously measured in each trap.
d. A system for dredging sand from the traps and transporting it as a
hydraulic slurry through a closed conduit back to the updrift end of the
facility.
This chapter begins by describing the design of the major components of the
sediment trapping system. The design and general operation of the dredging
system is then discussed. The next section describes results obtained from a
series of static performance tests conducted with the facility drained and the traps
empty, to verify the operation of the 20 sediment traps. The last section
discusses results from a set of dynamic performance tests conducted using
regular and irregular waves, to assess the structural integrity of the trap design as
well as the signal to noise ratio of the measurements. The data acquisition
system used to measure the quantity of sand in each trap, along with the real-time
display system used to visualize the measured data, will be discussed in
Chapter 6.
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Chapter 4
Sediment Trapping and Dredging Systems
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