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Urban Flood & Climate Change

----information from APWMF and SIWW

Jinping LIUHydrologistTyphoon Committee Secretariat

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The Asia-Pacific Water Minister’s Forum (APWMF)

June 28, 2010 Jointly organized by MEWR and PUB of Singapore , and in cooperation with APWF.

Attended by Ministers and water leaders from 15 countries.

Themed ‘Water Security—Good Governance and Sustainable Solutions’.

Articulated the region’s water issues, policies and solutions.

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Singapore International Water Week (SIWW)

June 28 ~July 1, 2010.

Inaugurated with 2nd World Cities Summit (WCS).

Themed ‘Sustainable Cities: Clean and Affordable Water’ for SIWW.

Themed ‘ Liveable & Sustainable Cities for the future’ for WCS.

Around 10,000 participants from more than 100 countries and regions.

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Urbanization Affecting Flood Risk

Climate Changes Affecting Flood Risk

Approaches: Adapting to Climate Change

Urbanization Affecting Flood Risk

Climate Changes Affecting Flood Risk

Approaches: Adapting to Climate Change

Today’s presentation

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Urban/rural population for less and more developed region

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Urbanization - Tsurumi River Basin

1975

1995

Population increased by 1.7 　million in 40 years.85% of the river basin urbanized.It has become a typical urban river.

1958 Urbanization Rate

Natural

Urban

1975

1995

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Influence of Urbanization on Flood Risk

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Rainfall pattern is changed.

Annual Precipitation in Macao in the period of 1901~2008

Heavy rainfall in a city of Japan (1990~1999)

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Hydrological response is changed.

•Less infiltration

•More runoff

•Higher velocity

•Shorter travel time

•Higher peak flows

•More frequent channel forming flow

•Lower low flows

= Extremes

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Flow Increase & Time of concentration Decrease

Present

　　 Past

Time

Dis

charg

e

Inte

nsity

mm

/hr

duration

1:10 yr1:50 yr

20 60

frequency

70 mm/hr

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Urbanization Affecting Flood Risk

Climate Changes Affecting Flood Risk

Approaches: Adapting to Climate Change

Urbanization Affecting Flood Risk

Climate Changes Affecting Flood Risk

Approaches: Adapting to Climate Change

Today’s presentation

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Heavy Precipitation Events: Frequency increases over most

areas

Anomalies (%) of the global annual time series defined as the percentage change of contributions of very wet days from the base period average.

Kobe, Japan2008

IPCC AR4(Prof. Toshio Koike, The University of Tokyo )

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It is very likely that heavy precipitation events will continue to become more frequent.

IPCC AR4

> 90%

Projected changes in extremes:

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Recent trends, assessment of human influence on the trend and projections for extreme weather events for which there is an observed late-20th century trend.

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0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

CGCM3.1(T47)CSIRO-Mk3.5

INM-CM3.0PCM

CNRM-CM3MRI-CGCM2.3.2

GISS-AOMECHO-G

ECHAM5/MPI-OMCSIRO-Mk3.0GFDL-CM2.1

MIROC3.2(medres)CCSM3

CGCM3.1(T63)GFDL-CM2.0

MIROC3.2(hires)IPSL-CM4

Araki & Koike, 2008

Average=1.2

(from 17 models)

Ratio of Daily 10year Probable Rainfall between 50 years later according to A1B and the current, from 17

models

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Discharge(m^3/s)

T

Current Design Rainfall

Future Design Rainfall under

Climate Change

Design HydrographDesign HydrographDesign RainfallDesign Rainfall

1 1.2

HydrologicalModel

Current Climate

Climate Change

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Current Flood safety level

Target Flood safety level

Uncertainty

Basin wide measures1:80

1:150

1:80

1:150Future under climate change

Current DesignFuture Design

underClimate Change

Design Flood Control Design Flood Control

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Climate Change Impacts on Flood Control Planin Indonesia

10year Probable flood Current Climate

10year Probable flood 50 years later

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Urbanization Affecting Flood Risk

Climate Changes Affecting Flood Risk

Approaches: Adapting to Climate Change

Urbanization Affecting Flood Risk

Climate Changes Affecting Flood Risk

Approaches: Adapting to Climate Change

Today’s presentation

• In responding to Climate Change, investment for prevention under uncertain targets is extremely difficult, especially for developing countries.

• The best option is to take an adaptive approach that build climate resilience into development strategies.

• Adapting to What?– As the future is unknown, adaptation should be

flexible, incremental and capable of incorporating changes based on new knowledge.

– It should be a continuous process guided by sustainability concerns and address multiple needs.

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Quantifying uncertainty

Climate models

Multi-model ensemble (MME)

Down-scaling

Basin-scale prediction of quantity & quality

Water quantity and quality prediction

flood

ordinary water

drought

ground water

Information

Storage

Treatment

Current facility, plan, management

Flood control system

Water allocation

& cost

Environ-ment

Human life

Industry

HumanBehavior

EconomicBehavior

DroughtDisaster potential

FloodDisaster potential

Impact assessm

ent

Filed survey

Early warning

Allocation policy

Land use

Adaptation options

etc.

Innovative technology

- Flood control- quality control

Decision m

aking

Monitoring evaluation

implem

entation

End to End Approach on Climate Change Adaptation

IntegratedObserved Data Sets

ProcessStudy

Scientific approach Engineering Approach Socio-economical approach

(Prof. Toshio Koike, The University of Tokyo )

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Rotterdam Climate Adaptation Strategy 1.0Rotterdam Climate Adaptation Strategy 1.0

Ad

apti

ve B

uild

ing

Acc

essi

blit

y

Urb

an W

ater

Sys

tem

Cit

y C

limat

e

Flo

od

Man

agem

ent

CLIMATE PROOFRotterdam 2009

CLIMATE PROOFROTTERDAM 2025

CLIMATE PROOFROTTERDAM ....

Monitoring

Action

Assessment

Implement

Ro

ad

ma

p

knowledge

Arnoud Molenaar

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Concluding Remarks

• Climate Change, Urbanization and Urban migration are the greatest challenges for urban flood disaster risk reduction.

• Flexible adaptive measures - adaptive adaptation - should be mainstreamed. Innovative holistic approaches based on risk assessment are needed to achieve this.

• Urban flood is not isolate issue. UFRM should be integrated with holistic urban system.

• Urban flood is a kind of resources. UFRM is not to simply discharge flood out side of city, but to promote the beneficial and abolish the harmful.

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ThanksThanks

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