Flood risk, flood prevention and flood
insurance in The Netherlands
Karel Heynert & Laurens Bouwer
Deltares, The Netherlands
This talk…
The Netherlands - delta of 4 international basins
Amsterdam
Ems
Rhine
Scheldt
Meuse
Schiphol
4
The Netherlands – protected by levees
Total
Vulnerable
to flooding
Surface
Area
41.528 km²
55%
Inhabitants
16,8 million
60%
GNP
700 billion $
65%
Flood protection in The Netherlands (current)
Return periods…
4,000yr
53 flood protection areas (dike rings)
Protection level based on probability of
exceedance of design waterlevels
5 different protection standards
Procedure in Water Act
Formal verification: every 6 yrs
1,250yr
10,000yr
4,000yr
2,000yr
Towards a flood risk based approach…
Decision making based on flood risk
Still largely an engineering approach, but…
Flood risk…
 Unprotected areas: flood hazard * vulnerability (mapping)
 Areas with flood defences: failure probability * consequences
(calculations)
Rationale for investments in flood defences…
• Economic viability
• Probability of loss of life < 10-5
Computing flood risk…
?
Computing flood risk…
Potential direct damage per dike ring
in M€ (in 2020)
Verwachte schade bij optreden overstroming (situatie 2020)
Potential inundation depth in
(meter)
Vlieland
Overstromingskans
Biesbosch
Schiermonnikoog
1/2000
Terschelling
1/5000
Eempolder
1/10000
Ameland
1/20000
Gorssel
1/50000
Noord Beveland
1/100000
IJsselland
Pernis
Friesland en Groningen
Arnhemse- en Velpsebroek
Zeeuwsch Vlaanderen
Ooij en Millingen
IJsseldelta
Rozenburg
Tholen en St. Philipsland
Mastenbroek
Zutphen
Noordoostpolder
Goeree-Overflakkee
Oost Veluwe
Land van Altena
Texel
Vollenhove
Bommelerwaard
Zuid Beveland oost
Schouwen Duivenland
Hoeksche Waard
Some points of attention…
Donge
Noord-Holland
Wieringen
Land van Heusden/de Maaskant
Rijn en IJssel
Salland




‘Indirect’ damage
Critical infrastructure
Not all parts of levee system are equally important
Flood protection units interact
Lopiker- en Krimpenerwaard
Kromme Rijn
Gelderse Vallei
Zuid Beveland west
Land van Maas en Waal
West-Brabant
Walcheren
Flevoland
Voorne-Putten
Eiland van Dordrecht
IJsselmonde
Betuwe, Tieler- en Culemborgerwaarden
Zuid-Holland
Alblasserwaard en Vijfheerenlanden
0
10000
20000
30000
40000
50000
60000
Schade (mln euro)
Potential loss of life…
Local individual risk of death
P < 10^-7
10^-7 < P < 10^-6
10^-6 < P < 10^-5
P > 10^-5
Flood prone
Not flood prone
Water
Not NL
Preventing loss of life…
 Flood protection
 Flood warning & crisis management
Time to onset of flooding
Direct (< 6 hrs)
Fast (6-24 hrs)
Slow (> 24 hrs)
13 april 2015
Flood insurance…
Insurability of flood damage in The Netherlands
X
Local flood damage → ordinary insurance policies
1: Water damage in house (rain)
2: High groundwater
3: Sewer flooding
4: Polder water system
Figure: Matthijs Kok
Insurability of flood damage in The Netherlands
X
Figure: Matthijs Kok
Local flood damage → ordinary insurance policies
1: Water damage in house (rain)
2: High groundwater
3: Sewer flooding
Flooding, due to failure of defences → coverage ??
4: Polder water system
5: Failure regional flood defence
6: Failure of primary flood defence
7: Unembanked areas
Flood insurance in The Netherlands…
Building and home content policies
Crop loss insurance stopped in ‘09
Government compensation act (WTS)
New disaster insurance…
 Flooding, terrorism, earthquake etc
 Limited to 75 k€ per insured object
 Limit in nr of households in ‘unit’
Flood insurance pool proposed by
Dutch Association of Insurers…
 Obligatory, incl. in house insurance!
 Annual max. coverage: 5,000 M€
 Seems rejected by NL cartel authority
Future direction of flood insurance?
Flood risk management policy based on:
 Prevention
 Optimal investments
 Prevention of loss of life
High protection levels
Infrequent events
High accumulation risk
Limited flood awareness (?)
Public anticipation of role government
So where should we with flood insurance?
Mainly for regional water systems?
< 100 €/ha
100-1,000 €/ha
1000-10,000 €/ha
10,000-100,000 €/ha
> 100,000 €/ha
How to balance between
investments in flood protection and
relying on flood insurance?
Thank you!