Environmental Engineering Reference
In-Depth Information
Table 9.1
The accuracy of maximum inundation height hindcast (unit: m)
HYBRID
3D/2D
2D
Q3D
RMSE MAE
STD
RMSE MAE STD
RMSE
MAE
STD
Kamaishi
3.1
2.5
1.9
2.4
1.7
1.9
3.5
2.6
2.2
Ryoishi
2.9
2.4
3.3
3.3
2.6
3.9
2.8
2.6
3.0
Heita
3.7
3.6
1.2
1.3
1.2
1.3
3.7
3.7
1.6
Mean
3.3
2.6
4.7
2.9
2.0
5.5
3.5
2.7
4.8
Maximum Velocity [m/s]
39.31
39.3
39.29
39.28
39.27
39.26
39.25
39.24
39.23
141.88
141.9
141.92
141.94
141.96
141.98
142
0
2
4
6
8
10
12
Fig. 9.4
Maximum depth integrated horizontal velocity by the Q3D model
models overall. As a result, the depth-averaged momentum can vary quite
signifi cantly depending on the numerical model. Due to page limitation, there is no
space to discuss the accuracy of velocity but Fig.
9.4
shows the maximum velocity
distribution by the Q3D model. The maximum velocity is reached at 12 m/s and the
high velocity regions are located near shore and landside. The numerical modelings
of these regions are sensitive to local acceleration of fl uids and are highly dependent
on the numerical scheme.
Concluding the above discussion, the tsunami wave reduction by offshore break-
water can be estimated in the range of 20 % error and it can be improved by further
development of the numerical scheme. The reduced tsunami energy in Kamaishi
Bay gives different damage characteristics compared to Otsuchi Bay, which will be
discussed in the next section.
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