EM 1110-2-1100 (Part III)
30 Apr 02
EXAMPLE PROBLEM III-2-1
FIND:
Determine the K parameter for use at a site using Bailard's (1984) and del Valle, Medina, and
Losada's (1993) relationships, then calculate the potential volumetric longshore transport rate along the
beach using each K value.
GIVEN:
Waves having an rms wave height of 2.0 m (6.7 ft) break on a quartz sand beach with median grain
size, D50 = 1.0 mm at a wave breaking angle αb = 4.5o. The temperature of the seawater is 20o C and wf
= fall velocity = 13.1 cm/sec. Assume κ = 1.0 for this problem.
SOLUTION:
wf = 13.1 cm/sec (0.43 ft/sec), which is within Bailard's data range.
The maximum oscillatory velocity magnitude is calculated from Equation 2-9 as
κ ( g db )1/2
1 (9.81 2.0)1/2
umb '
'
2
2
umb = 2.21 m/sec, which is within Bailard's (1984) data range.
Therefore, Equation 2-8 may be used, and the coefficient to apply in the longshore sediment transport
equation is,
K = 0.05 + 2.6 sin2 (2αb) + 0.007 umb/wf = 0.05 + 2.6 sin2 (2(4.5o)) + 0.007 (2.21/0.131)
K = 0.23
Applying del Valle, Medina, and Losada's relationship, Equation 2-10,
(&2.5 D50)
' 0.12
K ' 1.4 e
(Continued)
III-2-16
Longshore Sediment Transport
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