28. October 2015 FEWS-RISK: A STEP TOWARDS RISK- BASED FLOOD FORECASTING D. Bachmann D. Eilander, A. de Leeuw, K. de Bruijn, F. Diermanse, A. Weerts, J. Beckers, P. Gijsbers, M. Ponziani (Deltares, NL) L. Boelee, C. Hazlewood, E. Brown (HR Wallingford, UK) FEWS-User Days 2015, Deltares Delft
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DSD-INT 2015 - FEWS-risk a step towards risk-based flood forecasting - Daniel Bachmann
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28. October 2015
FEWS-RISK: A STEP TOWARDS RISK-
BASED FLOOD FORECASTING
D. Bachmann
D. Eilander, A. de Leeuw, K. de Bruijn, F. Diermanse, A. Weerts, J.
Beckers, P. Gijsbers, M. Ponziani (Deltares, NL)
L. Boelee, C. Hazlewood, E. Brown (HR Wallingford, UK)
FEWS-User Days 2015, Deltares Delft
28. October 2015 Daniel Bachmann
28. October 2015
Common practice in operational flood forecast
Hydrology (catchment)
Hydrodynamic (river)
Meteorology (catchments)
Forecasted
process chain System river
t
h
Precipitation,
temperature,
wind etc.
Discharge
Water level
Water level
time series
Daniel Bachmann
28. October 2015
How to make a decision based on water levels?
Daniel Bachmann
• How will my flood defence line
perform?
• What will be the impacts of
flooding? Crisis
manager
System river
t
h
Water level
time series
28. October 2015
Extension by workflow 1
Hydrology (catchment)
Hydrodynamic (river)
Meteorology (catchments)
Forecasted
process chain
System river and flood
defence line
t
h
Water level
Failure
analysis (flood defence line)
In advance
Fragility
curve
Reliability
transformation
pf = 100%
Failure
probability
time series
Daniel Bachmann
28. October 2015
The concept of Fragility curves (FRC)
Summary of the performance or failure probability of a
structure depending to the load (e.g. water level [m])
Daniel Bachmann
28. October 2015
Determination of Fragility curves (FRC)
Daniel Bachmann
INPUT: Geometry, zonation, sub soil, soil
parameter etc.
28. October 2015
Support for decision makers by workflow 1
• Where is my weak section given the
hydraulic load?
• Where and when inspection should
increased or emergency measures
should be taken?
• Where and when a breach is
probable?
System river and flood
defence line
t
h
pf = 100%
Failure
probability
time series
Daniel Bachmann
Crisis
manager
28. October 2015
What happens if a breach occurs?
• How fast, how much and where the
water will flow?
• How relevant is the protection task
of this section?
• When and which emergency
measures should be triggered?
System river, flood
defense line, hinterland
Crisis
manager
Daniel Bachmann
28. October 2015
National Information system Floodmapping
Daniel Bachmann
Predicted hazard: Waterdepth after dike
failure for pre-calculated scenarios
28. October 2015
What happens if a breach occurs?
• How fast, how much and where the
water will flow?
• How relevant is the protection task
of this section?
• When and which emergency
measures should be triggered?
System river, flood
defense line, hinterland
Crisis
manager
Daniel Bachmann
28. October 2015
Extension by workflow 2
Breaching (flood defence line)
Impacts (protected area)
Police
Transformer
School
System river, flood
defence line, protected area
Hydrodynamic (river)
Hydrodynamic (protected area)
Forecasted
process chain
Water level
Discharge
Impacts to
people, critical
infrastructure
etc.
Flood spreading,
hydraulic values
Hospitall
Hydrology (catchment)
Daniel Bachmann
28. October 2015
Crisis
manager
Police
Transformer
School
System river, flood
defence line, protected area
Impacts to
people, critical
infrastructure
etc.
Flood spreading,
hydraulic values
Hospitall
Support for decision makers by workflow 2
Daniel Bachmann
• How fast, how much and where the
water will flow?
• How relevant is the protection task
of this section?
• When and which emergency
measures should be triggered?
28. October 2015 Daniel Bachmann
28. October 2015
The Rotterdam area and dike rings
• Western part of the Netherlands at the delta of Rhine
and Maas rivers to the North Sea
• Highly populated area (ca. 1.3 million people)
• High flood protection standards
Daniel Bachmann
Delft
28. October 2015
Reliability analysis
• 15 dike sections (14 in Ijsselmonde and 1 in Pernis)
• Pre-calculated fragility curves available
Daniel Bachmann
28. October 2015
Examples fragility curves
• Available fragility curves: km14_1, km47, Pernis