URBAN FLOOD ANALYSIS WITH UNDERGROUND SPACE - Advances in Geosciences - page 47

URBAN FLOOD ANALYSIS WITH
UNDERGROUND SPACE
KEIICHI TODA ∗ , KAZUYA INOUE and SHINJI AIHATA
Disaster Prevention Research Institute, Kyoto University
Gokasho Uji, Kyoto, Japan
∗ [e-mail]
In this study, an inundation simulation model based on a storage pond model is
developed which can treat inundation of both ground and underground spaces
in urban area. The continuity equation, momentum equation, and drop for-
mula are used as the basic equations in the model. The model is applied to
Fukuoka City in Japan, and Fukuoka flood inundation in 1999 is simulated
in both ground and underground spaces. The computation results show good
agreement with the actual record. The model is also applied to Kyoto City,
Japan. The results show that the large inundation into underground malls and
subways may occur in the case that the Kamo River overflows.
1. Introduction
When flood flow hits the central district of large cities, the inundation
flow would extend to underground space and the damage would be serious.
In fact, urban floods such as the ones that occurred in Fukuoka, Japan
in 1999 and in 2003 and the one that occurred in Seoul, Korea in 2001
induced inundation into underground space and caused extensive damage.
Therefore, it is very significant to study the inundation in underground
space from the hydraulic and disaster preventive aspects.
Takahashi et al. 1 early made an inundation flow model in underground
space. They treated the inflow from stairs into underground space as a
stepped flow. They also showed that a horizontally two-dimensional (2D)
inundation flow model can be applied to underground space. In their stud-
ies, only simple underground shapes were treated, and the effect of ceiling in
underground space was not taken into account. The authors 2 developed the
underground inundation model based on the one-dimensional (1D) network
model with a slot, and applied it to Umeda underground mall in Osaka,
Japan. They could succeed in treating the real complicated underground
space and expressing both of the open channel flow condition and the pres-
surized flow condition. In their models, however, the flow behavior cannot
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