experiments and an analysis of the equilibrium beach profile for this grain size
(Dean 1977). The height of the berm was selected so that the maximum
excursion of wave runup in the swash zone would not reach the upper elevation
of the berm. The front slope of the berm (approximately 1:5.5) was chosen based
on the results of preliminary moveable-bed experiments. The main section of the
beach was graded to have a constant slope of approximately 1:27, extending from
the initial still-water shoreline, offshore to 16 m from the onshore boundary. The
toe of the moveable-bed beach slopes down to the concrete beach on a 1:8 slope
and has proven to be stable for the wave conditions tested. The objectives in
designing this initial beach profile were to minimize the time required for the
beach profile to approach equilibrium, and to simplify the shape of the profile so
that the beach could be regraded to this initial shape on a regular basis. The
calculated equilibrium beach profile for this sediment size also is shown in
Figure 4. The process of initially grading the beach to have straight and parallel
contours and the procedure used to adjust the updrift and downdrift boundaries of
the beach is discussed in Chapter 5.
0.5
Concrete Fixed-bed Profile
0.4
Initial Sand Beach Profile
0.3
Calculated EBP
0.2
Still-water Level
0.1
0.0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
-0.7
-0.8
-0.9
0
2
4
6
8
10 12 14 16
18
20
22
Cross-shore Location (m)
Figure 4.
Profile view of LSTF showing the concrete and sand beach profiles
Coordinate system
The coordinate system used in the facility is right-handed, with the origin at
the downstream, shoreward end of the wave basin. The positive x-axis is
directed offshore and is measured relative to the upper edge of the concrete beach
slope. The positive y-axis is directed upstream. The z-axis is measured
positively upward with the origin at the still-water level. The coordinate system
was chosen based on future plans to extend the length of the facility. However,
for simplicity, all downstream-directed longshore current speeds and flow rates
6
Chapter 2
Overview of the Laboratory Facility
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