水分野における水分野における

Mikio 　 IshiwatariSenior Advisor, Japan International Cooperation Agency

ISDR Asia Partnership Technical Workshop to Develop the Regional Roadmap for Promoting Regional Cooperation on Disaster Risk Reduction and Climate Change

Adaptation1-2 July, Bangkok

JICA’s 　 Initiative on Climate Change Adaptation in

Water Related Disasters

outlineoutline

1.1. Situation in JapanSituation in Japan

2.2. Staitionarity is deadStaitionarity is dead

3.3. JICA’s new initiativeJICA’s new initiative

4.4. Case study Case study

5.5. ConclusionConclusion

1

4

12 2

0

4

2

0

21

2

7

5

12

0 0 01

2 23

8

5 5

2

45

1

4

0

3

0

5

10

1980 1985 1990 1995 2000 2005

1976 ～ 1986 1987 ～ 19971998 ～ 2008

Daily rainfall over 200mm is significantly increasing

Recent change on Climate in Japan

×1.5Average3.5 days

1901～ 19301978～ 2007

Hourly rainfall over 100mm is increasing

Incidence of daily rainfall over 200mm per year

Average5.1 days

（ year ）

（ N

umb

er of incidence

）

Incidence of hourly rainfall over 100mm per year

（ N

umb

er of incidence

）

（ year ）

Average1.7 days

Average2.0 days

Average3.6 days

× 2.0

Source: JMA

Source: JMA

4

1.061.07

1.13

1.11

1.10

1.111.07

1.20～ 1.25

1.15～ 1.20

1.10～ 1.15

1.05～ 1.10

1.00～ 1.05

Legend

1.24

1.22

1.11

1.14

Rainfall after 100years is projected to increase 10 to 30% (max. 50%)

bigger increase in northern area

0

25

50

75

100

現計

画

北海

道

東北

Increasing rainfall intensity make flood safety level significantly lower than present

Flo

od

Safety

Level

Decline of flood safety level

Ａ Ｂ

Ａ

Ｂ

Future rainfall projected as a median value in each region

Average rainfall in 2080-2099 Average rainfall in 1979-1998

The maximum daily precipitation GCM20 (A1B scenario).

Projection of future Climate

Presen

t

5

1/150

Present　 Future (100years later)

1/150

Runoff regulation measures in basin

Runoff regulation measures in basin

Crisis management and EvacuationCrisis management and Evacuation

Runoff regulation measures in basin

Runoff regulation measures in basin

Collaboration with regional DevelopmentCrisis management and Evacuation

Reevaluated safety level

Present Safety Present Safety Level deteriorate Level deteriorate significantly by significantly by

future increase of future increase of rainfallrainfall

1/40 Target of Safety Level

Target of Safety Level

Target of Safety Level

Basic concept for managing increasing risks

- Multiple measures in flood management -

2. Stationarity is dead2. Stationarity is dead

2. Stationarity is Dead2. Stationarity is Dead1)

we are in troublewe are in trouble

☹Under changing and uncertain climateUnder changing and uncertain climate Climate is changingClimate is changing

Return period (ex. 100 years flood or 10 years drought) Return period (ex. 100 years flood or 10 years drought) is never foundation of planningis never foundation of planning

Prediction possible, but with uncertaintyPrediction possible, but with uncertainty

☺Conventional Method of Water PlanningAssumption: fluctuate within an unchanging envelope of variability

New Designing methods of water infrastructures are needed

River bank heights, dam reserve capacity, bridge heights etc.

Furthermore……1) Milly P. C. D., J. Betancourt, M. Falkenmark, R. M. Hirsch, Z. W. Kundzewics, D. P. Lettenmaier, R. J. Stouffer (2008), Stationarity is Dead: Whither Water Management, Science. 319, p. 573-574.

Can we continue to construct higher Can we continue to construct higher dykes according to increasing flood dykes according to increasing flood scale? scale?

2. Stationarity is Dead 2. Stationarity is Dead Is flood Control Philosophy Dead, also?Is flood Control Philosophy Dead, also?

Conventional philosophy is abandoned.Conventional philosophy is abandoned.““Long liner bank system along river from Long liner bank system along river from river mouth to mountain”river mouth to mountain”

Proposed philosophyProposed philosophy““Multi-layered measures in river basin”Multi-layered measures in river basin”1) Step 1: Strategic area protect by structures1) Step 1: Strategic area protect by structures2) Step 2: Urban planning and land use 2) Step 2: Urban planning and land use

regulation for risk areasregulation for risk areas3) Step 3: CBDM3) Step 3: CBDM

2. Stationarity is Dead 2. Stationarity is Dead Flood Control Philosophy is Dead as Well.Flood Control Philosophy is Dead as Well.

2. Stationarity is Dead 2. Stationarity is Dead Sustainable society resilient to changesSustainable society resilient to changes

1.1. to respond continuously changing climateto respond continuously changing climate2.2. to plan and implement infrastructure projects to plan and implement infrastructure projects

through predicting future impacts with through predicting future impacts with uncertainty uncertainty

3.3. to change systems of water management to change systems of water management according to developing technology for according to developing technology for prediction and adaptation of climate change prediction and adaptation of climate change

3. JICA’s new 3. JICA’s new initiativeinitiative

Pahang

Muar

Climate change predictionClimate change predictionensemble of GCMensemble of GCM

Climate change Climate change adaptation measuresadaptation measures

Governance at river basin levelGovernance at river basin level various sectors, organizations, stakeholders are various sectors, organizations, stakeholders are

involvedinvolved Need for consensus building and responsibility Need for consensus building and responsibility

sharingsharing Structure measuresStructure measures Non-structural measures, early warning and Non-structural measures, early warning and

evacuation evacuation Land use regulationLand use regulation CBDMCBDM Capacity DevelopmentCapacity Development MonitoringMonitoring Poverty alleviation and consideration on Poverty alleviation and consideration on

vulnerability group vulnerability group

4. Case study 4. Case study

4-1 Tagaloan River Basin, the 4-1 Tagaloan River Basin, the PhilippinesPhilippines

50 yrs flood → 25yr flood in 2050

100 yrs flood → 25-50yr flood in 2100

Increase rate of rainfall

intensity (%)

Design rainfall (mm)

Probable Flood Discharge

(m3/s)Scenario

 

Return period (year)

5yr 10yr 25yr 50yr 100yr 25yr 50yr

  Status quo - 125 142 164 181 198 4190 4770

  A1F1 2050 11 150 170 197 217 237 4780 5720

  2100 14 161 183 211 233 255 5400 6150

  B1 2050 20 138 157 182 200 219 4650 5290

  2100 29 142 162 187 206 225 5030 5430

Tagaloan River Basin, the Tagaloan River Basin, the PhilippinesPhilippines

PlanningPlanning

Original MP Revised MP

Tagaloan River Basin, the Tagaloan River Basin, the PhilippinesPhilippines

4-24-2．．Metro Manila Suburb, Philippines : Cavite Area

River BasinRiver Basin Catchments Area Catchments Area (km2)(km2)

River Length River Length (km)(km)

ImusImus 115.5115.5 45.045.0

San JuanSan Juan 147.76147.76 43.443.4

CanasCanas 112.32112.32 42.042.0

ResidualResidual 32.8432.84 --

TotalTotal 407.4407.4

0

200

400

600

800

1000

1200

1400

0 6 12 18 24 30 36 42 48

Time (Hour)

Disc

harg

e (m

3/s)

Qp = 880m3/sStates Quo

Qp = 1,090 m3/sYear 2050 under Secenario B1

Qp=1,300m3/sYear 2050 under Secenario A1FI

Fig. 1 General Map of Study Area

Case Case No.No.

Scenario of Climate ChangeScenario of Climate ChangeUrbanized Urbanized

RatioRatio

Probable Flood Inundation Area (kmProbable Flood Inundation Area (km22))Number of Houses/Buildings InundateNumber of Houses/Buildings Inundate

d (thousandd (thousand houses) houses)

Flood Depth bFlood Depth below 1melow 1m

Depth aboDepth above 1mve 1m

TotalTotalFlood DepFlood Depth below 1th below 1

mm

Flood DepFlood Depth above 1th above 1

mmTotalTotal

11 Status QuoStatus Quo 26%*26%* 31.5131.51 1.051.05 32.5632.56 20.120.1 1.71.7 21.821.822 States QuoStates Quo

43%**43%**

35.8235.82 1.501.50 37.3237.32 31.431.4 2.92.9 34.434.433 In 2050 under B1 ScenarioIn 2050 under B1 Scenario 41.1041.10 2.522.52 43.6243.62 35.535.5 4.44.4 39.939.944 In 2050 under A1FI ScenarIn 2050 under A1FI Scenar

ioio 44.6444.64 3.543.54 48.1848.18 38.438.4 5.95.9 44.344.355 States QuoStates Quo

65%***65%***

41.0541.05 2.452.45 43.5043.50 56.456.4 7.27.2 63.663.666 In 2050 under B1 ScenarioIn 2050 under B1 Scenario 43.9243.92 2.972.97 46.8946.89 60.160.1 8.58.5 68.668.677 In 2050 under A1FI ScenarIn 2050 under A1FI Scenar

ioio 47.2747.27 3.983.98 51.2551.25 63.063.0 11.211.2 74.274.2

  

×3200821,800 houses

205074,200 houses

危険地域の家屋数危険地域の家屋数Houses at risk areaHouses at risk area

気候変動Climate Change

都市化　 Urbanization

海面上昇Sea Level

雨Rain

表面流Surface flow

洪水Floods volume

危険地域の家屋Houses at risk area

危険地域Risk area

multiplication of CC and multiplication of CC and UrbanizationUrbanization

遊水地計画を将来拡張する可能性→ 都市計画に開発抑制地域として線引き

適応策検討　適応策検討　 Climate Change AdaptationClimate Change Adaptation

Off-site Flood Retarding BasinPartial River Improvement SectionOff-site Flood Retarding BasinPartial River Improvement Section

１．河川工事・遊水地River improvement works

2.土地利用規制Land Use Control

3. 調整池 Retarding Basin in Urban area

Fig. 22 Land Zoning in the Lower Reaches of Study AreaDescriptionDescriptionPeak River Discharge Peak River Discharge

before Retardingbefore RetardingPeak River Discharge Peak River Discharge

after Retardingafter RetardingReduction of Peak Reduction of Peak

DischargeDischargeStorage Storage

VolumeVolumeAreaArea

Proposed in the Proposed in the StudyStudy

430 m430 m33/s/s 245 m245 m33/s/s 185 m185 m33/s/s 1.87 (101.87 (1066mm33)) 45ha45ha

Required in 2050 Required in 2050 B1 ScenarioB1 Scenario

550 m550 m33/s/s 245 m245 m33/s/s 305 m305 m33/s/s 3.01 (103.01 (1066mm33)) 75ha75ha

Required in 2050 Required in 2050 A1FI scenarioA1FI scenario

690 m690 m33/s/s 245 m245 m33/s/s 445 m445 m33/s/s 4.06 (104.06 (1066mm33)) 100ha100ha

適応策 Climate Change Adaptation土地利用規制　 Land Use Control

On-site Flood Regulation Pond

(3% of Sub-Division)

Dry Type

Wet Type

• Offset increment of peak runoff discharge

• Control sediment runoff

New Sub-Division

Creek

気候変動適応　 Climate Change Adaptation　宅地での調整池　 On-site Regulation ponds

For Evacuation

For Warning

簡易観測

River Water Level Indicator for Flood Warning and Evacuation

適応策　 Climate Change Adaptationソフト対策　 Software measures

ハザードマップ

適応策　 Climate Change Adaptationコミュニティ防災　 Community based disaster management

適応策　 Climate Change Adaptationコミュニティ防災　 Community based disaster management

5. conclusion5. conclusion

Climate is changing in Japan, and new poliClimate is changing in Japan, and new policy is reported. cy is reported.

Startionarity is dead, flood control philosopStartionarity is dead, flood control philosophy either?hy either?

JICA’s Handbook for Climate Change AdapJICA’s Handbook for Climate Change Adaptation in Watertation in Water

Proposed method of CCA in flood risk manProposed method of CCA in flood risk management is applied in the Philippinesagement is applied in the Philippines

JICA handbookJICA handbook

Ver.0 was producedVer.0 was produced

Ver.1 will be issued at the end of FY2010Ver.1 will be issued at the end of FY2010Comments are welcomedComments are welcomedIshiwatari.mikio@jica.go.jpIshiwatari.mikio@jica.go.jp

Study AreaStudy AreaRiver BasinRiver Basin C.A.C.A.

Kalu River basinKalu River basin 2,719km2,719km22

Kelani River basinKelani River basin 2,292km2,292km22

Gin River basinGin River basin 932km932km22

Nilwara River basinNilwara River basin 971km971km22

Study ScheduleStudy Schedule

Climate change predictionClimate change predictionStudy in South Western Sri LankaStudy in South Western Sri Lanka

Work inSri Lanka

Work inJapan

First Year Second Year2010 2011

21 months (from January 2010 to September 2011)

Projected Rainfall Data from CMIP3

Projected Rainfall Data of GCM20(1979-1998, 2080-2099)

Note: CMIP3: Phase 3 of Coupled Model Intercomparison Project GCM20: General Circulation Model (20km grid) APHRODITE: Asian Precipitation-High Resolved Observational Data Integration Towards Evaluation of the Water Resources

Recorded Rainfall Data in Project Area

Mesh Rainfall data fromAPHRODITE daily precipitation

(1) Data Collection

(2) Examination of Appropriateness of GCM20 by Comparison with CMIP3 Rainfall Data

(3) Bias Correction and Statistic Downscaling

(4) Evaluation of Flood Risk (Hydrological and Hydraulic Analyses)

Climate change predictionClimate change predictionStudy in South Western Sri LankaStudy in South Western Sri Lanka

10回以下

40約 回

100約 回

020406080

100120

1900

1910

1920

1930

1940

1950

1960

1970

1980

1990

2000年

回

Annual frequency of inundation of the corridor of Itsukushima Shrine in Hiroshima (Graph prepared by the Chugoku Regional Development Bureau based on a diary of Itsukushima Shrine.)

1 0 1 14

0 0 02 1

30

1210 11

17

7

22

0

5

10

15

20

25

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

Itsukushima Shrine in Hiroshima was inundated less than five times a year in the 1990s. about ten times in the 2000s. 22 times a year in 2006 and is still increasing.

-St. Mark's Square in Venice was flooded less than ten times a year at the beginning of the 20th century. increase to about 40 times a year by 1990 and to as many as 100 times a year in 1996.

-250 times of inundation a year in 2006.

*At present, it is not clear whether the increase of inundation risk is attributable to global warming or not but there may be a possibility.

Annual frequency of inundation of St. Mark's Square in Venice, Italy (Graph prepared based on the Economics of Climate Change by Stern Review.)

593

879

海面上昇後

１．５404人口（万人）

１．５577面積（k㎡）

倍率現状

593

879

海面上昇後

１．５404人口（万人）

１．５577面積（k㎡）

倍率現状

Increases of below-sea-level areas in three large bay areas (Tokyo Bay, Ise Bay and Osaka Bay)

*Prepared by the River Bureau based on the national land-use digital information.

*Shown are the areas at elevations lower than sea level shown in a three-dimensional mesh (1 km x 1 km). Total area and population are based on three-dimensional data.

*No areas of surfaces of rivers or lakes are included.

*A premium of 60% is applied to the potential flood risk area and to the population vulnerable to flood risk in the case with a one-meter rise of sea level.

Areas with flood risks due to high tides will increase.

Ise Bay

Kawagoemachi to Tohkai City

Osaka Bay

Ashiya City to Osaka City

Tokyo Bay

Yokohoma City to Chiba City

Impacts of sea level rise:Increase of areas below sea level, and of risks of inundation due to high tides

Increase of risks of inundation due to high tides

５

5. Impacts of sea level rise

Frequency (times)

Less than ten times

About 100 times

About 40 times

PresentAfter sea level rise

Rate of increase

Area (km2)

Population (in tens of thousands of people)