Toshio OKAZUMI

Flood Risk Assessment and Disaster Data - Users’ perspective -

Chief Researcher International Centre for Water Hazards and Risk Management

(ICHARM) /Public Works Research Institute (PWRI)

October 1, 2013 “Expert Group Meeting on Improving Disaster Data

to Build Resilience in Asia and Pacific” Sendai, Japan

6 March, 2006 at Tsukuba

ICHARM

International Centre for

Water Hazard and Risk

Management under the auspices of UNESCO hosted

by PWRI, Tsukuba

Objective: To serve as the Global Center of Excellence to provide and assist implementation of best practicable strategies to localities, nations, regions and the world to manage the risk of water related hazards including floods, droughts, land slides, debris flows and water contamination

Advanced Early Warning System IFAS

ICHARM’s Policy : Localism Delivering best available knowledge to local practices

Local Practices

Integrated

Flood Analysis

System (IFAS)

Flood risk assessment

under climate change

Supported by MEXT

Master Course

Hazard Mapping Course

River & Dam Course

IFI

WWAP, AWDO

IFNet/GFAS

Sentinel Asia

Flood Preparedness

Indicators/Standard

WWF, APWF

The 1st Phase

Focus: Flood-related

Risk Management

Education Research

Ph.D. Course

Supported

by JICA

UNESCO Centers

IRDR

UNISDR GP-GAR

Working as a Knowledge Hub on WD through RETA

Supported by ADB UNESCO Pakistan pjt

Users’ Perspectives on Disaster Data

1. Definition of Terminology

2. ICHARM Challenges

a. Global Risk Indices

b. Flood Risk Assessment in River Basin

3. Conclusions

1. Definition of Terminology

Risk = Hazard × Vulnerability

Risk

Avoidance

(moving to safer location, etc.) is one good measure of disaster management

Hazard

Community/ Society

Hazard

Community/ Society

However, we cannot avoid hazards to come in most cases

The First Capacity: Prevention : Hazard cannot enter because of Preventive measures

Coping Capacity

Prevention

Hazard

Community/ Society

Hazard

Community/ Society

Hazard

Community/ Society

The Second Capacity: Coping Capacity: Hazard can enter Vulnerable situation but coping capacity will reduce the damage from hazard

Definition of terminology

8

Words Definitions Remarks

Vulnerability Amount of Potential Damage caused to a system by a particular climate-related event or hazard.(Jones and Boer 2003)

Unit is monetary value

Hazard A dangerous phenomenon, substance, human activity or condition that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage.

Non-Dimension (Probability)

Risk The combination of the probability of an event and its negative consequences.

Unit is monetary value

9

Risk = f ( HAZARD , Vulnerability ) = f ( HAZARD , Exposure, Basic Vulnerability, Capacity) Indicator of extreme statistics of hazard type

Affected by particular event (e.g. Population and property)

• Exposure in Flood Inundation Area To identify sensitivity of Exposure (E) to change flood prone area (H)

A potential social factor which causes exacerbation of the damage

• Disaster damage Not only hazards but also vulnerability, the human side of disaster causes, should be expected per area (maximum loss of persons and asset)

H E

2. ICHARM Challenges

a. Development of Global Risk Indices

I. BASIC PHILOSOPHIES

07/10/2013 11

There are a lot of questions in the existing global risk

assessment methods.

- Most of all, risk is estimated by the conceptual structure, and as a result, indices are far from real phenomena.

- Meanwhile, the upcoming global disaster risk reduction framework (HFA2) will require “evidence-based risk information”.

To explain real phenomena, the new methodology for risk

indices should be developed in the following manners:

- Upscale localized or river-basin leveled methods in assessing risks - Simplify those methods with consideration of data availability - Develop global risk indices with good credibility

RISK

ASSESSMENT

07/10/2013 12

II. OUTLINE For a comprehensive, integrated, multi-disciplinary approach

Quantifying our present risks

Preparedness

Assessment

Vulnerability

Assessment

Quantifying natural aspects of present risks III

IV

V

HAZARD

ASSESSMENT

I • Output: how hazardous are natural conditions?

• Example: flood inundation depth in an area

EXPOSURE

ASSESSMENT

II • Output: how many people or assets are affected by hazards?

• Example: number of people in hazardous areas

• Output: what factors increase or decrease potential damage? - identification of factors which influence risk

• Example: proxies related to marginalized group, unplanned urbanization, political corruption, and coping capacity • Output: how people or our assets

would be damaged?

• Example: fatalities, asset losses, and productivity losses

• Output: evaluation of effectiveness of disaster risk reduction actions (including structural & non-structural measures)

• Example: how effectively DRR education and early warning systems would reduce the present risks

Actions & well-

designed monitoring

activities

Global BTOP model of ICHARM

1. BTOP model – schematic diagrams 2. DEM upscaling (60N-60S)

Method descriptions

- Block TOP model with Muscingum-Cunge river discharge routing

- Cell size: 20 km losses DEM up-scaling

Advantages and possibilities

- Distributed hydrological model

- Runs on individual river basin

- Global application with up to 1 km

- Poorly gauged basins with satellite precipitation data

APPLICATION: Daily River Discharge

Green : 1km to 20km Blue : 90m to 20km

PROTOTYPICAL OUTCOMES OF ICHARM (1)

PROTOTYPICAL OUTCOMES OF ICHARM (2)

FID simulation

Method descriptions - Topographical algorithm for computing the

potential flood inundation depth

Advantages and possibilities - High resolution (500m ~1km) in global scale

and run time is fast - Globally acceptable performances - GIS-based approach, encouraging spatial

risk assessment

Condition

50-year return period discharges based on the

BTOP model From MRI-GCM3.2S BC (1980-2004)

(m3/s)

SPAHigh : 500000

Low : 0

Present_peak_discharge

SRTM DEM(HydroSHED15S)

Global FID

Shallow: 0.1 m

deep : over 10 m

FID =ƒ (DEM, Hmax, Flow direction, i ) Hmax = { Qmax * n0/(Bf*If)}^0.6

Input Data:

HydroSHED global-scale

Potential Flood inundation depth

PROTOTYPICAL OUTCOMES OF ICHARM(3)

1. Input conditions () : floodwater depth and population data2009 (1km)

Population distribution > 1 person/ km2

2. Results of exposure assessment 12S

47E 147E

56N

Affected people

Thin: 1 person/km2

Dense : over 1000

Coupling FID simulation and LandScanTM Method descriptions

- calculation of affected people by overlapping FID simulation results and high-resolution digital population map

Merits and advantages - reliable to estimate affected people in the

unit cell, because of high resolutions of FID and LandScanTM

- GIS-based approach, ensuring the further spatial risk assessment

1. Input conditions Flood hazard and exposure: FID simulation in case of 50-year return period discharge.

<ASIAN APPLICATION: 14 countries >

47E 147E

56N

12S

Affected people

Thin: 1 person/km2

Dense : over 1000

1. Study sites: 14 countries in Asia Flood hazard and exposure - simulated at the 50-year return period Proxies for vulnerability and risk calculation formula - estimated

2. Results of mapping flood risk Affected people: 1km cell-gridded Risk index (flood fatalities) was measured at country level, but it was possible to anticipate hotspots within the country.

<FLOOD RISK MAP> Kazakhstan RISK = 0.01

Bangladesh RISK = 0.16

Nepal RISK = 0.14

Pakistan RISK = 0.08

Cambodia RISK = 0.07

Viet Nam RISK = 0.06

Laos RISK = 0.04

Thailand RISK = 0.05

India RISK = 0.06

Indonesia RISK = 0.04

Korea RISK = 0.03

Japan RISK = 0.01

Philippines RISK = 0.06

Tajikistan RISK = 0.02

RISK = flood fatalities per 100 km2

07/10/2013 17

III. ADVANTAGES AND POTENTIALS IN ICHARM’S RISK ASSESSMENT METHODS

HAZARD ASSESSMENT - APPROACH: global BTOP, and FID simulation - ADVANTAGES: overcoming data unavailability of developing countries with simplified

hydrological models

EXPOSURE ASSESSMENT - APPROACH: GIS-based assessment through coupling of FID simulation and LandScanTM - ADVANTAGES: reliable to estimate affected people for each grid-cell

VULNERABILITY ASSESSMENT - APPROACH: selection of more direct proxies, and application of advanced statistical methods - ADVANTAGES: evidence on importance of various proxies at the disaster damage viewpoint

RISK INDEX CALCULATION - APPROACH: organization of all data into risk indices by using the risk calculation formula - ADVANTAGES: risk indices are not conceptual, and enable us to consider various hydro

extremes, and important social conditions

POTENTIAL AS A VEHICLE FOR POLICY-MAKERS AND DECISION-MAKERS - Providing risk information with “much higher credibility”

2. ICHARM Challenges

b. Flood Risk Assessment in River basin

Process of Flood Risk Assessment

1. Data collection and analysis on precipitation

2. Data Collection and analysis on information in river basin 3. Inundation simulation

Runoff calculation Hydraulic analysis Inundation analysis

4. Assessment of Hazard and Vulnerability ×

<Hazard> Analysis on Inundation area, depth, duration and reach time

<Exposure> Analysis on Vulnerability of Population, Assets, infrastructures, Core functions

5. Risk Assessment

<Assessment area> Economic Damage, Human Casualty, Impact and Damage to Urban function, Recovery, Indirect impact to private company

<Assessment method> Quantitative assessment Qualitative assessment

data

technology

(Source: River and Sabo technical guideline, MLIT-Japan)

20

Water depth / duration distribution

House damages

Damages calculations

Agricultural damages

Damage curves

House value distribution

Cultivation starting date

Results

Calculation

Example;

Uncertainty Estimation during Flood Risk Assessment in the

Pampanga River, the Philippines

21

22

Pantabangan dam

Arayat

San Isidro

Metro Manila

Pampanga river basin A= 10,434km2

Angat dam

1

10

100

0 1000 2000 3000 4000 5000

Ret

urn

Peri

od

Discharge（m3/s）

Gumbel

Gumbel

Arayat_revised

Arayat_original

so

Correction of observed data

Gap = 20%

San Antonio Swamp

Candaba Swamp

Max inundation depth in Sep 2011 flood

Results of Runoff model Flood simulation (flood in Sep 2011)

San Isidro

Mayapyap

(m)

(m)

Retarding effect of Swamp can be seen in hydrograph

Land Use in Pampanga river

Change of Land Use at San Isidro 24

1

10

100

0 1000 2000 3000 4000

Ret

urn

Peri

od

Discharge (m3/s)

Annual maxiumdaily dischargeGumbel

IFAS

BTOP sm

Uncertainty of runoff model selection

Gap = 40%

Result of Rainfall and Runoff Inundation(RRI) model simulation in Sep 2011 flood

Every hour from Sep 26 to Oct 4 (9 days)

Water Depth(m) 26

Growth stage

Days of submerge 1-2 3-4 5-6 7

Estimated yield loss (%) Vegetative stage: Minimum Tillering /Maximum Tillering

10-20 20-30 30-50 50-100

Reproductive Stage: Panicle Initiation/Booting Stage (Partially Inundated)

10-20 30-50 40-85 50-100

Reproductive Stage: Panicle Initiation/Booting Stage (Completely Inundated)

15-30 40-70 40-85 50-100

Maturity Stage: Flowering stage 15-30 40-70 50-90 60-100 Ripening Stage 5 10-20 15-30 15-30

Flood damage matrix: Rice Damage

0

20

40

60

80

100

1-2 3-4 5-6 7

Pe

rce

nta

ge o

f Y

ield

Lo

ss

(%)

Durations of Flood (Days)

Ripening

0

20

40

60

80

100

1-2 3-4 5-6 7

Pe

rce

nta

ge o

f Y

ield

Lo

ss

(%)

Durations of Flood (Days)

Maturity

0

20

40

60

80

100

1-2 3-4 5-6 7

Pe

rce

nta

ge o

f Y

ield

Lo

ss

(%)

Durations of Flood (Days)

Vegetative

0

20

40

60

80

100

1-2 3-4 5-6 7

Pe

rce

nta

ge o

f Y

ield

Lo

ss

(%)

Durations of Flood (Days)

Reproductive

Ranges of yield loss of rice due to flood

Drought damage matrix: Rice and Corn Damage

Growth stage

Estimated yield loss (%)

PALAY CORN Seedlings 40 25 Vegetative 50 50 Reproductive 60 80 Maturity 15 15

Agricultural Damage can be defined as:

= function ( flood duration, growth stage)

Risk Assessment: Agricultural Damage (Flood and Drought)

Maximum damage with location of Pampanga province and Calumpit Municipality

Minimum damage with location of Pampanga province and Calumpit Municipality

Max - Min Gap = 50%

Observed data Hazard Analysis

Flood Reproduction calculation

Risk Assessment

so sm sr

S

Field investigation Satellite info

Flood Mark Inundation map Satellite observation (MODIS, SAR, PRISM)

Damage data Damage function Satellite image

20

%

40

%

50

%

Uncertainty estimation during Flood Risk Assessment Uncertainty reduction method

Necessity data for Flood risk assessment

1. Hydrological data ; to identify hazard and its probability, validation of hydrological and hydraulic model ( professional agency)

2. National Statistics; to identify exposure with overlaid to No.1(population, asset, etc.)

( National Statistic Office)

3. Damage data; to identify risk (causality and economic losses), validation of risk model

( this should be enhanced)

Results of Risk Assessment will be utilized as decision-making info. Reduction of uncertainty as much as possible is important.

Thank you very much