Effects of Climate Change on Natural Disasters at Coastal Zones

Kazuya Yasuhara, Ph DProfessor

Ibaraki University, Department of Urban &Civil Engineering,

4-12-1 Nakanarusawa-cho, Hitachi-city, Ibaraki, 316-8511, Japan.

E-mail: yasuhara@mx.ibaraki.ac.jp, Fax: ≁81-294-38-5268, Phone:≁81-294-38-5166

Research program by coastal hazard and adaptation group

(1) Climate-change susceptible function for economic assessment

(2) Coastal hazards induced by a rising sea level, storm surges and river floods: adaptation strategies and assessment of submergence and risks

(3) Prediction and adaptation to damage of riverbanks and coastal grounds resulting from rising sea-levels caused by global warming

(4) Geo-hazards triggered by climate change and great earthquakes: evaluation and adaptation strategies

(5) Assessing risks of heavy rains and rising sea-levels caused by global warming in coastal areas

Disasters caused by overlapping of multiple phenomena triggered by global warming

Figure

Climate-change triggered

No climate- change associated

SLR Typhoon

Rainfall

Vulnerable natural background

Vulnerable social & humane background

Compound disaster

Water disaster

Geo-disaster

Earthq. Land sub.TectonicMovem.

Compound Disaster

Examples of global warming-triggered events

Torrential rainfall

SLR

TyphoonStorm surge

Rise in GWL

Liquefaction

Earthq.

(A typical example of Water disaster)

(A typical example of soil disaster)

Storm Surge

Storm surge and river inundationStorm surge and river inundation

Population and economic data

Population and economic data

Topographical data

Topographical data

Flooding(Level flood

method)

Flooding(Level flood

method)

Damage of inundated area

Damage of inundated area

•Area•Population•Cost

Indirect effects to the economy

(productivity/flow)

Indirect effects to the economy

(productivity/flow)

Damage cost

(assets/stock)

Damage cost

(assets/stock)

1E3

1E2

1E1

1E0　ha

Decrease in Agricultural productivity

Storm surge(West-Japan)

River flooding(4 main rivers)

SLR, TyphoonSLR, Typhoon

Inundation at the three major Bays

(b) Ise Bay(a) Tokyo Bay （c）Osaka Bay

(After Suzuki, 2007)

（SLR 60cm，storm surge increase ratio 1.3 at 2030 ）

Inundation caused by storm surge increases at the lowland and reclamation area at the three bays.

Variation of inundation damage

0

2

4

6

8

10

12

14

16

18

20

『0.1』 『0.4』 『0.7』 『1.0』 『1.3』 『1.6』

被害

額（兆

円）

海面上昇0ｃｍ 海面上昇20cm海面上昇40cm 海面上昇60cm海面上昇80cm 海面上昇100cm

東京湾

0

2

4

6

8

10

12

14

16

18

20

『0.1』 『0.4』 『0.7』 『1.0』 『1.3』 『1.6』

被害

額（兆

円）

海面上昇0ｃｍ 海面上昇20cm海面上昇40cm 海面上昇60cm海面上昇80cm 海面上昇100cm

伊勢湾

0

2

4

6

8

10

12

14

16

18

20

『0.1』 『0.4』 『0.7』 『1.0』 『1.3』 『1.6』

被害

額（兆

円）

海面上昇0ｃｍ 海面上昇20cm海面上昇40cm 海面上昇60cm海面上昇80cm 海面上昇100cm

大阪湾

台風強度

台風強度 台風強度Intensity of typhoon (Isewan-Typhoon as a standard)

(Estimation is based on the manual of MLIT）

(a) Tokyo Bay (b) Ise Bay (Nagoya) © Osaka Bay

Change in inundation area Change in inundation area in the Pacific coastin the Pacific coast

-20 0 20 40 60 80 100

海面上昇（cm）

0

20,000

40,000

60,000

80,000

100,000

120,000

浸水

面積

（ha）

0.7 1 1.3 1.6高潮増大率

0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7

高潮増大率

0

20,000

40,000

60,000

80,000

100,000

120,000

浸水

面積

（ha）

-20 0 20 40 60 80 100海面上昇 (cm)

(a) Influence of SLR (b) Influence of SSIR

Inundation area is sensitive to SLR.

Change in economical loss caused by storm Change in economical loss caused by storm surge in the Pacific coastsurge in the Pacific coast

-20 0 20 40 60 80 100

海面上昇（cm）

0

10

20

30

40

50

60

70

被害

額（T

\）

0.7 1 1.3 1.6高潮増大率

0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7

高潮増大率

0

10

20

30

40

50

60

70

被害

額（T

\）

-20 0 20 40 60 80 100海面上昇 (cm)

(a) Influence of SLR (b) Influence of SSIR

Inundation damage cost is also sensitive to SLR.

Liquefaction

(Great Hanshin Earthquake, 1995, Japan)

Recent situation of rainfall in Japan (after JMA, 2006)

0

1

2

3

1976 1981 1986 1991 1996 2001 2006

Appearance counts per year of which amount of precipitation per day

is larger than 400mm

Appe

aran

ce c

ount

s pe

r yea

r(A

t 100

obs

erva

tion

poin

t)

Year

Average in 1976-19860.5

Average in 1987-19960.4

Average in 1997-20061.2

0

5

10

15

20

25

30

35

1976 1981 1986 1991 1996 2001 2006

Increasingtendency

Num

ber

of

appea

rances

(At

100

obs

erv

atio

n po

ints

)Year

1976-1986 average16.0times/100point

1986-1996 average17.7times/100point

1996-2006 average23.2times/100point

(a)Appearance counts per year larger than 400mm in Japan

(b) Number of appearance larger than 50mm in Japan

(a) Variations of occurrence frequency of earthquake with 5 strong seismic intensity

Occ

urre

nce

freq

uenc

yO

ccur

renc

e fr

eque

ncy

(b) Variations of occurrence frequency of earthquake with 6 weak seismic intensityYear

Year

Occurrence frequency of recent earthquakes in Japan(arranged using data from JMA, 2006)

PurposePurposeVulnerability to

liquefaction hazards in theobjective region has beenassessed throughcomparison of GIS-aidedliquefaction hazard mapsbefore and after SLR andclimate change caused byglobal warming.

Tokyo Bay

Tokyo Bay

Objective area

Economical loss for eastern lowland of TokyoEconomical loss for eastern lowland of Tokyo

Objective area: coastal area in the eastern part of Tokyo

・Collection of ground data・Ground modeling・Estimation of rise in GWL caused by climate change and SLR ・Estimation of economic loss

Distribution of liquefaction hazard

(a) Scenario I (present situation)

(b) Scenario II(consideration of SLR in 2100)

(c) Scenario III(consideration of rainfall from 2081 to 2100)

(d) Scenario IIV(both SLR and rainfall from 2081 to 2100)

Liquefaction resistance factor, FL

Evaluation of possible liquefaction through depth in an objectivEvaluation of possible liquefaction through depth in an objective e location using the method proposed by Iwasaki et al.(1996)location using the method proposed by Iwasaki et al.(1996)

Bor

ing

log

Bor

ing

logzz

00hh

∫=20

0)()( dzzwzFPLFL

FL

FL

FL

FL

FL

FL

FL

Integration of the liquefaction

potential through depth, using this

equation..

⎩⎨⎧

>≤−

=1011

)(L

LL

FFF

zF

zzw 5.00.10)( −=

(a) Scenario I(present situation)

(b) Scenario II (consideration of SLR in 2100)

(c) Scenario III (consideration of rainfall from 2081 to 2100)

Distribution of economical damage caused by earthquake

(d) Scenario IV (both SLR and rainfall from 2081 to 2100)

Increase in economic damage from the present situation to the scenario IV

Economical loss induced by liquefaction is4 thousand billion Yen approximately in the case of both SLR and heavy rainfall considered.

Liquefaction damage has appeared rather in land than along the coast.

Possible adaptation to natural disasters at coastal zonesAdaptation

Protection Accommodation Evacuation

Storm surge & River flood

Additional bankingWater protection workEarly warning system and evacuation systemConstruction of shelter

Hazard mapAppropriate land use Regulation of land usein hazardous areaInsurance

Restriction of developmentEvacuation from dangerous areaPublic support for evacuation

Lique- faction

Monitoring of GWLLowering of GWLAdditional bankingSoil improvement and reinforcement

Hazard mapAppropriate land use Regulation of land usein hazardous areaInsurance

Restriction of land useEvacuation from dangerous areaPublic support for evacuation

Slope failure

Protective pileEarly warning system and evacuation system

Hazard mapRisk map Regulation of land usein hazardous areaInsurance

Restriction of land useEvacuation from dangerous areaPublic support for evacuation

Conclusion1) Sea level rise and buildup of high tides triggered by global warming expand the flooding area and population. As global warming progresses, reclaimed lands developed long ago will face a high risk of flooding by high tides in the inner parts of the three large bays.

2) Sea level rise and anomalous rainfall raise the groundwater level and expand areas that suffer geotechnical hazards through liquefaction in the event of an earthquake.

3) The procedures for estimating economical loss induced by storm surge and liquefaction are presented. The results should be put to good account for proposal of the appropriate adaptation.