Asian and Pacific Coasts 2005
September 4-8, 2005, Jeju, Korea

Development on Integrated Numerical Research System
for Prevention and Estimation of Coastal Disaster
Hidenori Shibaki1, Jong-In Kim2, Hiroyuki Iwase1, and Nobuhiko Hara1

1. INTRODUCTION
Severe environmental conditions persist along thecoast of Japan with huge waves, storm surges andtsunamis. Oceanographical disasters are occurring
every year around the coastal and estuarine areas ofJapan. In September 1959, an abnormal high stormsurge caused a coastal disaster with flooding over alarge area around the Ise Bay, which is located in thecenter of Japan, and with the loss of more than 5,000lives. This storm surge was generated by theTyphoon number 5915 (named Isewan Typhoon). InMay 1960, the Chilian earthquake tsunami caused acoastal disaster with an inundation of large coastal
areas facing the Pacific Ocean. Against these coastal
disasters, the research on prevention of coastal
disaster is actively conducted, and many coastal
structures have been planned and built for disastermitigation. Hard countermeasures, like theconstruction of various structures as coastal dikes,
seawalls and breakwaters, are effective to reduce thedamage up to the level of disasters to which thestructures were designed. However, the hardcountermeasures have a limitation in their disasterprevention capacity against disasters over the designlevel. To remedy the deficiency of hard ones, soft
countermeasures, which mean a provision of theinformation on the disaster mitigation andevacuation methods, are promoted. The soft
countermeasures can be more useful for disastermitigation than the hard ones, depending on thesituation.
To determine design conditions and to prepare
disaster-related information, the characteristics ofdisaster phenomena must be clarified with scientificmethods. The INSPECT (Integrated Numericalresearch System for Prevention and Estimation of
Coastal disasTer) system has been developed forcoastal protection works composed of hard and soft
countermeasures.
2. OUTLINE OF INSPECT SYSTEMThe INSPECT system consists of three numericalsimulation models (Wave, Storm Surge andTsunami models), their supporting sub-systems andsupporting databases. Fig. 1 shows the compositionand functions of the system. Several systems,supporting sub-systems and databases are utilizedfor such analyses.

INSPECT
SystemWave Climate
Statistic Analysis
SystemWave Statistic Analysis
Design Wave Analysis

Wave Hindcasting
SystemCoastal Wave Hindcasting
Inland Sea Wave Hindcasting

Storm Surge
Computation
SystemInland Sea Wind Hindcasting
Storm Surge Simulation

TsunamiComputation
SystemNear-field Tsunami Simulation
Transoceanic Tsunami Smulation

Supporting
SystemWeather chart data processing
Bathymetric Data processing
Wave Transformation Analysis
Animation processing

Supporting
Database

Observed Wave-Tide Database
Weather Chart Database
Bathymetric Database
Computed Wave-Tide Database

Fig. 1. Composition and functions of the INSPECTsystem

1Environmental and Hydraulic Engineering Department, ECOH CORPORATION, Tokyo 110-0014, Japan

2Hydro-Environment Research Institute, GeoSystem Research Corporation, Goonpo 435-824, Korea

年
年
105 110 115 120 125 130 135 140 145 150 155 160 165 170 175

3. NUMERICAL SIMULATION MODEL

Coastline in 1970115

3.1. Wave Hindcasting Model
The INSPECT wave model is a shallow-water wave
hindcasting model, based on spectral calculations,
incorporating wave generation, wave decay andwave transformation. The model is able to simulate
wave fields composed of wind waves and swells.
The governing equation of wave hindcasting is theenergy balance equation.
Fig. 2 shows the spatial variation of wave heightclose to coastline. The processes of wave refraction,wave diffraction and wave shoaling outside the surfzone, and wave decay by wave breaking inside thesurf zone, are taken into account.
3.2. Storm Surge Model
The INSPECT storm surge model gives an accurate
tide anomaly by incorporating several effects suchas multi-level flows, density stratification, wave
setup, river discharge and inundation. The
magnitude of wave setup can be calculated from thedivergence of the radiation stresses. The results ofwave hindcasting with a shallow-water wave model
are used for the calculation of the radiation stresses.
The radiation stresses for each layer are utilized theformulas by Longuet-Higgins and Stewart (1964).
The basic equations of storm surge model are themulti-level continuity and momentum equations
integrated for each layer. In the momentum
equations, the shear stresses (wind stress at the sea
surface, inner stress between two layers and bottom
shear stress), the pressure gradients (atmosphericpressure, water level and water density) and thedivergence of the radiation stresses are taken into
consideration. More details about basic equations ofsimulation model are explained in Shibaki andWatanabe (2002).
Fig. 3 shows that the maximum tide level
deviations in Kochi Port calculated with the effectof inundation upon attack of a T7010-class typhoon.
The change of tide level deviation due to the effectof inundation is about -0.3 m in an inner bay.
3.3. Tsunami Model
The INSPECT tsunami model gives an accurate
estimate of wave height and velocity byincorporating several effects such as nonlinear wave
dispersion, wave breaking and bottom frictionestimated with land conditions.
Fig. 4 shows the tsunami propagation computedby the nonlinear dispersive equation model (Iwase

115

Unit: m110

110

3.0
1.5

105

105

100

100
2.0

95

9.5

1.5

9.0

90

8.0

2.5
85

6.5
4.5 6.0

80

7.5

1.5

75

9.5
1.0

65

1.5

60

0

5.5

70
65

10.0

4.5

2.5

80
75

9.5

70

55

9.5

9.5
9.5

90
85

10.0

8.5
9.095

60 Ｎ

10.05510.0
2.0105 110 115 120 125 130 135 140 145 150 155 160 165 170 175
0500
1000 (m)
2468
1012m
5.5

Fig. 2. Spatial variation of maximum significant
wave height upon the attack of Typhoon 7010
around the coastlines of Kochi Port
Coast line in 1970
Effect of inundation

最大津波水位 ( m )（1970年 8月20日18時 － 1970年 8月21日21時）
50
100
150
200
250
300
0.4
400

0.8
1.5

350

1.6 1.4
300

200

0.2

0.6

0.8

350

1.0 0.4
300

1.2
1.5

250

400

0.8

1.0

250

0.8 1.0

1.9m

200

150

150
2.0
1.4

1.7m
100

100

1.0

Ｎ

0.4
50
1.8
50
0.0

1.0

100

150
2.050

1.4
200

3.0 m

2500300
13752750 (m)Fig. 3. The maximum deviations of tide level inKochi Port calculated with the effect of inundation
upon attack of a T7010-class typhoon

Fig. 4. Tsunami propagation computed by thenonlinear dispersive equation model on the northAkita coastand Imamura, 2003). The process of generation ofsoliton fission waves at the point of depth of about 8
m by the leading wave of the 1983 Nihonkai-Chubu
earthquake tsunami and the breaking of these waves
at the depth from 6 to 4 m is presented in thediagrams. This tsunami simulation has been appliedwith the Aida fault model (1984) as the initialcondition and yielded the results more accurate andstable than the previous shallow water equation
models.
4. DATABASES AND APPLICATIONS
4.1. Databases
The INSPECT system includes several databases fornumerical simulation on coastal disasters. Fig. 4
shows a three-dimensional view of the sea bottom
topography around Japan and land topography ofJapan. The data around the target area are selectedfrom a topographic database before the performanceof numerical simulations in the specific areas.
Fig. 5 shows a three-dimensional view of thetopography of and buildings in an area selected fornumerical simulation of the inundation. This
diagram is made by using GIS data about theinformation of buildings.
4.2. Applications
Fig. 6 shows a two-dimensional tsunami hazard map
with the information of tsunami inundation height,
topography, buildings, and routes at urban area. The
tsunami inundation heights were calculated bynumerical simulation for the purpose of tsunami
evacuation planning. Similar maps have been
prepared at several tsunami hazard areas in Japan.

Simulation Results+GIS data

Bottom Topography
Coastal LineLand Topography

Select of any area

Fig. 4. Three-dimensional view of sea bottom
topography around Japan and land topography ofJapan

Maximum Tsunami HeightFig. 6. Two-dimensional tsunami hazard map
informed with tsunami inundation height,topography, buildings, and routes at urban area

Making of Land
Constructions
with GIS data

Fig. 5. Three-dimensional view of topography andbuildings

Fig. 7. Three-dimensional view of topography andbuildings together with simulated inundation fieldFig. 7 shows three-dimentional view of
topography and buildings together with thesimulated inundation field. Such an application ofnumerical tsunami simulation helps citizens tounderstand clearly the tsunami damage and provides
the useful information about the hazardous areas.

advices. The authors also would like to record theirsincere thanks to the late Dr. Chiaki Goto for his
valuable ideas and advices, and they lament his
premature death three years ago.

REFERENCES
5. CONCLUSIONThe INSPECT (Integrated Numerical research
System for Prevention and Estimation of Coastal
disasTer) system has been developed for coastal
protection works composed of hard and soft
countermeasures. The INSPECT system isemployed to efficiently perform studies forpreventing disasters on Japanese coasts due towaves, storm surges, and tsunamis. The system
continues to be upgraded and to be extended fornumerical studies of all coastal and estuarine areasof Japan.
ACKNOWLEDGMENTS
The authors would like to express their thanks toEmeritus Prof. Yoshimi Goda at Yokohama
National University and Emeritus Prof. Akira
Watanabe at University of Tokyo for their precious

Aida, I., 1984. A source model of the tsunami
accompanying the 1983 Nihonkai-Chubu
Earthquake, Bull. Eartheq. Res. Inst., Vol.59,
235-265.
Iwase, H. and F. Imamura., 2003. A new tsunami
numerical simulation with Boussinesq-type
equations applied for the 1983 Nihonkai-Chubu
Earthquake Tsunami, Proc. of the 2nd Int. Conf.
Asian and Pacific Coasts 2003, 12-13.
Longuet-Higgins, M.S. and R.W. Stewart., 1964.
Radiation stresses in water waves: A physicaldiscussion with applications, Deep-Sea Res.,
Vol.11, 529-562.
Shibaki, H. and A. Watanabe., 2002. Study ofmulti-level simulation model for storm surge
considering density stratification and wave setup,J. Hydraulics, Coastal and Envir. Eng., JSCE,
No.719/Ⅱ-61, 47-66 (in Japanese).