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1 Flood Vulnerability Analysis Session 2 Dr. Heiko Apel Risk Analysis Flood Vulnerability Analysis.
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Transcript of 1 Flood Vulnerability Analysis Session 2 Dr. Heiko Apel Risk Analysis Flood Vulnerability Analysis.
1
Flood Vulnerability Analysis
Session 2
Dr. Heiko Apel
Risk AnalysisFlood Vulnerability Analysis
2
Learning objectives
Risk AnalysisFlood Vulnerability Analysis
Get familiar:
With the principles of flood vulnerability analysis
With the elements at risk
Learn:
The exposure mapping of elements at risk
Systematic classification of flood losses
How to collect food loss data and build flood loss models in general
Specific insights in the flood loss analysis of buildings, agriculture and lives
Understand:
The importance of impact and resilience on flood losses
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Vulnerability analysis provides
Understanding of vulnerabilities in order to identify efficient measures to reduce them and to minimize impact of future floods
The foundation for cost-effective planning of flood mitigation
The inputs for realistic flood scenario modeling emergency planning
Data for risk mapping to be used to improve public flood risk awareness, which can motivate precautionary measures
Input for financial appraisals for (re-)insurance to determine insurance rates, estimate probable
maximum loss (PML) to support disaster response and governmental decisions about loss
compensation immediately after floods
Data for the quantitative comparison of different risks within community or region
Risk AnalysisFlood Vulnerability Analysis
Elements at Risk
Economic sectors Housing Infrastructure
(traffic, power supply, water supply, administration)
Food production Transport Trade
Cultural sectors Cultural heritage Daily life
Social sectors Population Health care Food supply Mobility
Environmental Sectors Ecosystem stability Environmental
health (Pollution) Biodiversity
4Risk AnalysisFlood Vulnerability Analysis
5
Exposure Databases
Data should reflect the location and value of the assets at risk
Use analog maps or preferably GeoInformationSystems (GIS) for spatial reference, display and intersection
Explore the capabilities of remote sensing (RS) products for mapping of elements at risk
Most commonly used satellite imagery libraries: MODIS, LandSAT, ASTER, Quickbird, SPOT
Utilize statistical databases and spatial disaggregation methods to distribute aggregated values (e.g. dasymetric mapping)
Risk AnalysisFlood Vulnerability Analysis
6
Exposure Databases (cont.)
Examples:
Micro-scale: detailed topography and building location
Meso-scale: CORINE land use data set
Risk AnalysisFlood Vulnerability Analysis
7
Increase of flood plains and losses
Loss increase in the last decades:
Caused by: Increasing number of disasters River training Increasing use of floodplains (urbanization, population
growth) The accumulation of valuable goods Decreasing awareness of flood risk
Risk AnalysisFlood Vulnerability Analysis
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Flood impact classification
Risk AnalysisFlood Vulnerability Analysis
Flood Impact
Direct
TangiblePropert
y Damag
e, Infrastructure, Agricult
ure
IntangibleFatalities,
Evacuees,
Ecosystems,
Cultural Heritag
e
Indirect
Tangible
Disruption of Trade and
Traffic
Intangible
Psychological Stress, Migrati
on
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Factors affecting flood loss
Example: flood loss of buildings
Impact and resistance should be defined for every element at risk
Source: Thieken et al. (2005)
Risk AnalysisFlood Vulnerability Analysis
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The role of awareness and preparedness
Significantly reduces flood losses Example: loss in private households in the flood
of 2002 in Germany (questionnaire results, n 2150)
use
0
5
10
15
20
25
adapted not adapted
da
ma
ge
ra
tio
bu
ild
ing
[%
]
n = 78 580
furnishing
0
5
10
15
20
25
adapted not adapted
n = 67 589
heating, electr. utilities
0
5
10
15
20
25
in storeys in cellarn = 53 560
use
0
10
20
30
40
50
adapted not adapted
dam
ag
e r
ati
o c
on
ten
ts [
%]
furnishing
0
10
20
30
40
50
adapted not adapted
75%-Quantile
25%-Quantile
Median (50%-Quantile)
Mean
Source: Kreibich et al. (2005)
Mean damage reduction due to precautionary measures:
29.000 € (buildings) 31.000 € (assets) 24.000 € (utilities)
Risk AnalysisFlood Vulnerability Analysis
11
Scales of loss estimation
Scale of analysis determines data and methods:
Micro-scale Object specific Detailed input datasets (direct surveys)
required Cities, communes, counties Results aggregated, but detailed results
available
Meso-scale Regional to national Aggregated input data (statistics, census
data, land use units) Cumulated loss estimates, no site specific
interpretation possibleRisk Analysis
Flood Vulnerability Analysis
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Flood loss data collection
Is the first step for establishment and evaluation of loss models:
Problem: data availability and compatibility Different stakeholders (e.g. insurance industry, science,
public administration) collect data on flood losses with different methods:
Methods to collect data Building Surveyors – high level of standardization, consistent data
quality, limited set of parameters, expensive method (100 € per case*)
Questionnaires – answers dependent on respondents, unknown data quality, representativeness via sampling, lower cost (25-40 € per case*)
* Prices refer to Germany
Risk AnalysisFlood Vulnerability Analysis
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Flood loss assessment - buildings
Region specific Damage types:
Structural damage Contents
Differentiated into Building types: construction, materials, size, stories Building uses: private, commercial, industrial
Loss estimation Absolute or relative damage Loss functions: functional
relationship between flood indicators and damage (be careful to consider all factors)
Solution: rule based loss model
Risk AnalysisFlood Vulnerability Analysis
Private PrecautionNone Good
Very Good
Contamination None 0.92 0.64 0.41
Moderate 1.2 0.86 0.71
Severe 1.58 --- ---
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Flood loss assessment – buildings (cont.)
Rule-based flood Loss Estimation Model FLEMO (GFZ)
Source: Büchele et al. (2006)
0
5
10
15
20
25
30
35
< 21 cm 21-60 cm 61-100 cm 101-150 cm > 150 cm
Water level (above ground surface)
Lo
ss
ra
tio
of
a b
uild
ing
[%
] one-family house
(semi-)detached
multifamily house
poor/average building quality
high building quality
Step 2: modification of loss ratio (FLEMOps+)
Step 1: damage ratio estimation by water depths and rule based model FLEMOps (step functions)
Risk AnalysisFlood Vulnerability Analysis
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Flood loss assessment - agriculture
Two-step process: Relative loss estimation respective to season Estimation of regional market value of crops
Loss of wheat crops in an early summer flood in East Germany
Risk AnalysisFlood Vulnerability Analysis
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Flood loss assessment – loss of life
Data-based empirical approach (based on flash flood and dam failure data in USA, LOL = f(PAR)*, Source: Brown & Graham 1988 )
Process-based approaches (simulates exposure of people in buildings etc., evacuation possibilities and survival rates)
*Loss of life (LOL), Population at risk (PAR)
Risk AnalysisFlood Risk Analysis
Warning time Loss of lifeLess than 15 min 0.5 PAR
15 min – 1.5 h PAR0.56
More than 1.5 h 0.0002 PAR
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Flood loss assessment– loss of life (cont.)
Risk AnalysisFlood Risk Analysis
Example of processed-based approach:Hydraulic experiments by REDSCAM (2000), Helsinki University of Technology, Finland