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Slide1

http://www.d1.dion.ne.jp/~kwx/isewan.htm

Ise

Bay Typhoon in

1959：The greatest damage after WWⅡThe coincidence of flood and storm surge

on compound water related disaster in Japan

using 2D non-uniform flow model

Estimation of the damage cost

YUKAKO

TANAKA, SO KAZAMA, DAISUKE KOMORI, MASAHIRO AKIMA

Graduate School of Engineering, Tohoku University, Sendai, Japan

・

Typhoons which brought

particularly

enormous damageBackground1A flood (Typhoon No. 18, 2015)Kinu

River burst its banks for the first time in 29 years　　　　　　　

A flood

(Typhoon No. 10, 2016)

The typhoon hit the Tohoku district for the first time

Single disastersTyphoon Muroto (1934) 　Makurazaki Typhoon (1945)

Ise

Bay Typhoon (

1959

)

…

The

coincidence

of

Compound

disasters

flood

and storm surge

Background

2

http://311-ta--jinseidog.blogspot.jp/2014/07/blog-post_55.html

https://www.yodogawa.kkr.mlit.go.jp/activity/comit/develop/kisoan/glossary-ka.html＞＜ It is necessary for Japan

enormous

damage

×

low probability

T

he risk ofcompound disastershigh probability

×

less damage

single

disasters

T

he risk of

to evaluate

quantitatively the

risk of

flood,

storm

surge, compound

disaster

a

nd compare them

or

Previous studies

3

Flood damage estimations using the

distribution of rainfall causing any return period of flood　　　 (Tezuka et al.,2014 etc.)

Analysis on storm surge inundation damage using

numerical models　　　　　

(Suzuki, 2008 etc.)

Floods

Storm surges

Many studies have done on impacts on each flood and storm surge

Objectives

4

to calculate the inundation depth which is

storm surge

land

Sea area

land

inundation depth

Estimation on the damage cost

of compound disaster that flood and storm

surge happened

at the same

time

(

Akima

et al.

, 2016

)

!

T

he

inundation depth

was estimated on

the condition that highest tide level stay constant so far as the storm surge flooding

calculation

!

T

he

difference between the tide level and the ground elevation was regarded as the inundation depth of storm surge

The objective of my research

more

similar to the actual

phenomenon

Data set ～

single disasters～

5

Rainfall (mm/day)causing any return period of floodthe distribution of rainfall 　　　

・・・　 　　

96

Mean sea level

Tide

level deviation

Elaposedtime (hours)Tide level (m)

Floods

Any return

period

of

Storm surges

(

Tezuka

et al.,2014)

the

tide level

deviation calculated

by means

of frequency analysis

Data set ～

compound disasters～

6

Rainfall

・・・　 　　

96

Mean sea level

Tide level deviation

Tide level (m)

Tide level

Compound disaster

：

A

low pressure

bring flood

and storm

surge

one

after

another

at

the

same place

in 4 days

＝

causing any return period

of

the rainfall

compound

disaster

c

aused by

any return period

of

the rainfall

low

atmospheric pressure

annual minimum

atmospheric pressure

(

hPa

)

annual minimum

atmospheric pressure

(

hPa

)

Tide

level

d

eviation (

cm

)

Rainfall

(mm/day

)

Elaposedtime

(hours)

Method

7

・Rainfall： 0～24h (constant)・Tide level：

0

～24h (time series)

prices per unit of area calculated by each land use

Tide

level (m) Inundation depth

Damage cost

Input to

Rainfall

(

mm/day

)

2D non-uniform flow model

Result ～

damage cost distribution～

8

Total amount of the potential damage costin whole Japan for 50-years return periodof compound disaster

75 trillion JPYMillion

＝1,000,000 (0は6)１億　＝ 1,0000,0000 (0は8)Billion＝

1,000,000,000 (0は9)１兆　＝1,0000,0000,0000 (0は12)Trillion＝1000,000,000 (0

は12)

P

otential damage cost (billion JPY)Potential damage cost (trillion JPY)compound disasterin

the part

of

the

compound disaster

e

ach event

flood

storm surge

Time

Flow

Result

～

difference in the time of storm surge～9Potential damage cost (billion JPY)The time set the highest tide level (hours)

Rainfall

tide level

Time

Time

Flow

Time

w

hen the damage cost of

compound

disaster

reaches a

peak

The

time

at that

the highest tide

level

is

set

30 hours after rain

started

3.7

trillion JPY

Result ～

difference from previous studies～

10

smaller by 13trillion JPYthe rate of decrease in damage cost

(%)

15.2

% decrease

The damage cost of compound disaster in this study is

smaller

than that in previous study (Akima et al., 2016) This difference could be caused by the difference in infiltrationof tidal waves to the land

Niigata, Ishikawa,

Kochi…particularly

overvalued

this study

previous study

Result～

comparing the risk of each event～

11

Useful for efficient adaptation method against water disasters80% of prefectures: Storm surge＜Compound disaster＜FloodFlood

Storm

surgeCompound disaster

Flood

Storm surge

Compound disaster

The greatest risk is brought by :annual expecteddamage cost

（

billion JPY

）

Annual

expected

damage cost

ware estimated

considering water disasters

control projects

Floods

pose

the

greatest risk

Conclusions

12

1

. Improvement of Flood simulationtime series variation of tide level was taken into the model2. Change in the arrival time of storm surge

3.

Comparison

of

the risk of each disaster

Storm surge

＜Compound disaster＜Floodto evaluate quantitatively the risk of water related disaster and compare themObjective

Results

damage

cost reaches

a peak on the condition

that

the

time of the highest tide level

is

set at 30

hours

after rain started

洪水寄与降雨

13

手塚ら，

2013日本全国の任意地点における再現期間降雨

上流

降水量

どの地点でも

100

年に

1回の流量

集水面積に応じ重みをつけた降雨→流量を適切に評価

？

？

？

1/100

1/100

1/100

×

重み

下流

再現期間の洪水を生じさせる降雨分布

集水面積と流出係数の関係

浸水深被害率曲線

田の浸水深被害率曲線

畑地

の浸水深被害率曲線家屋の浸水深被害率曲線家庭用品の浸水深被害率曲線14

頻度分析の方法　～GEV

分布～

GEV分布…確率分布関数の一つ

15

（

のとき）

（ のとき） （ 母数）

http://311-ta--jinseidog.blogspot.jp/2014/07/blog-post_55.html

最大値抽出などの水文頻度解析において重要な役割を

担

う

二次元不定流モデル

重力による影響

地表面の粗度による影響

家屋に

よる

抵抗

の影響

局所項

移流項16…連続方程式…運動方程式（x方向）

二次元不定流モデル

17

重力による影響

地表面の粗度による影響

家屋に

よる抵抗の影響

F =

m

a

二次元不定流モデル　～差分法～

18

…

連続方程式…運動方程式（x方向）