ERDC/CHL CHETN-III-70
July 2005
Figure 4. Runup estimation using wave
Figure 5. Runup estimation using Coastal
formulas momentum flux formula (Eq. 13)
Engineering Manual converted to use
peak period, Tp (Eq. 4)
van der Meer and Stam (1992) determined their empirical runup equation by a direct curve fit to the
data. This procedure was able to represent the nonbreaking wave data better than the method of
applying a uniform reduction factor to the estimates for the corresponding runup on smooth slopes
using the plunging/spilling runup equation based on wave momentum flux. The nonbreaking wave
runup data were isolated and fitted with a separate curve, and this improved the wave momentum
flux estimates to equal those of van der Meer and Stam (1992). However, the improvement was not
significant enough to justify having two formulas when a single formula gives estimates comparable
to those of van der Meer and Stam.
EXAMPLE: IRREGULAR WAVE RUNUP ON ROUGH, IMPERMEABLE SLOPES:
Find: The vertical runup distance from the swl which is exceeded by only 2 percent of the waves
(i.e., Ru2%) for structure slopes of 1:2 and 1:4 (tan α = 0.5 and 0.25).
Given:
20 ft1
=
water depth at toe of slope
h
=
9.0 sec
wave period associated with spectral peak
Tp
=
8 ft
zeroth-moment significant wave height
Hmo
32.2 ft/sec2
=
g
tan α =
0.5, 0.25
structure slope
1
To convert feet to meters, multiply number of feet by 0.3048.
8