International Symposium on Tsunami Disaster Mitigation in Future
Jan. 17-18, 2005, Kobe, Japan
Joint Tsunami Runup Study
The National Science Foundation (NSF) funded a study beginning in FY92 to identify important
physical parameters involved in 3D tsunami runup. This joint research study included principal
investigators: Dr. Philip Liu, Cornell University, Dr. George Carrier, Harvard University, Dr. Harry
Yeh, University of Washington, Dr. Costas Synolakis, USC, and Dr. Michael Briggs, CHL. An
international advisory committee met with the principal investigators once a year and included Drs.
Howell Peregrine, University of Bristol, Fred Raichlen, Caltech, Nobu Shuto, Tohuku University, and
Robert Street, Stanford University.
Over the course of this study, several CHL flumes and basins were used to conduct four physical
models of a plane beach, vertical wall, and a circular island. Three conference and six journal papers
were authored or co-authored by CHL during the course of this study in national and international
publications. Two benchmark problems on the circular island and vertical wall were featured in the
International Workshop on Long Wave Runup Models (1996) that was attended by 55 international
scientists. Fujima et al. (2000) used the circular island data to verify their analytical solutions for the
propagation of tsunamis and the distribution of maximum runup heights around the island.
Plane beach
The first series of experiments was conducted in both a flume and a basin to study tsunami wave
evolution, uniformity, runup, and wave kinematics over a plane 1 on 30 beach. These data were
designed to produce high-quality laboratory data with physically relevant idealized tsunami conditions
for validating numerical models. Additional details can be found in Briggs et al. (1993, 1995a and b).
The flume data provided some small-scale comparisons to the larger-scale basin results and
information on velocities in the runup plume. Figure 1a is a schematic of the 42.4-m-long,
glass-walled flume used in the 2D flume study. The flat area in front of the toe of the 1 vertical on 30
horizontal sloping beach was located 21 m from the wavemaker. Water depth in the constant depth
region was 32 cm. Tsunami waves were simulated as solitary waves using a vertical hydraulic piston.
The 10 wave conditions ranged from nondimensional wave heights H=H/d =0.01 to 0.50. Ten
capacitance wave gages were used to measure surface wave elevations along the length of the flume.
The first gage was located 15 m from the wavemaker to measure incident wave conditions. Gages 2
to 10 formed a cross-shore transect in the center of the flume. A two-component laser Doppler
velocimeter (LDV) system was used to measure two orthogonal components of fluid velocity in the
plane of the flow. The LDV system was mounted outside the flume with four laser beams focused at
a point approximately 9 cm from the inside face of the glass flume wall.
A complementary experiment was conducted in a large-scale, 30-m-wide by 25-m-long wave basin.
The fixed-bed model included a flat section and a 1:30 sloping beach with plane parallel contours
(Figure 1b). The offshore water depth in the undisturbed, constant depth region of the model was
again 32 cm. The toe of the slope was located 12.4 m in front of the wavemaker. A directional
spectral wave generator (DSWG) was used to generate solitary waves. The electronically controlled
DSWG was 27.4-m-long and consisted of 60 paddles, 46-cm wide and 76-cm high. Eight target wave
heights from H=0.01 to 0.20 were simulated. All waves were non-breaking until final stages of
transformation near the shoreline (where gentle spilling occurred), except for H=0.20 waves which
broke nearshore. Thirty capacitance wave gages were used to measure surface wave elevations. The
first three gages were located at X=3, 6, and 9 m along the centerline in the constant depth region to
measure incident wave conditions. Twenty-seven gages were positioned in three cross-shore
transects in an 8-m by 6-m measurement area between the toe of the slope and the SWL to measure
wave evolution.
Changes in runup magnitude and in the shape of the runup tongue were investigated for selected
cases in the basin by varying the number of paddles used in each experiment and the eccentricity of the
source. The maximum vertical runup along the sloping beach was measured at each grid line above
the SWL.
Breaking occurred in both the flume and the basin near the shoreline for measured H > 0.04.
Normalized maximum vertical runup was plotted versus normalized wave height. Two distinct runup
regimes for breaking and non-breaking waves were found in accordance with earlier work of
Synolakis (1987).
Previous Page
