ABSTRACTS 'Extreme Discharges' - CHR-KHR

Increasing flood losses indicate increasing flood risk -
What are the responsible parameters?
Wolfgang Kron
Münchener Rück, München
Königinstrasse 107, D-80791 München, Germany
wkron@munichre.com
Increasing flood losses
Flood catastrophes and the resulting economic and insured losses have increased significantly in the past decades.
About a third of the economic catastrophe losses incurred worldwide are due to the effects of floods; more
than half of all the people that were killed in the natural catastrophes of recent decades were the victims of
floods. In global terms, the great flood catastrophes of the 1990s alone accounted for losses exceeding
US$200bn (Tab. 1). The comparison of decade figures clearly shows dramatic increases.
Table 1: Great flood catastrophes 1950–2004, decade comparison
1950–
1959
1960–
1969
1970–
1979
1980–
1989
1990–
1999
1995–
2004
Factor: last
10 yrs. : 60s
Number 6 6 8 18 26 15 2.5
Economic 32 23 21 30 245 154 6.7
losses
Insured
losses
0.0 0.25 0.4 1.6 8.8 8.3 33
MRNatCatSERVICE - Losses in US$ bn, 2004 values © Munich Re, Geo Risks Research – January 2005
Central Europe has experienced large events almost every other year during the past decade. The 1993 and 1995
floods in the Rhine system were followed by the Odra flood in 1997 and the Whitsun flood in Southern
Germany in 1999, and all these were dwarfed by the Elbe flood in August 2002. Then, Germany suffered
losses of €11.6bn, Austria and the Czech Republic added another €3.1bn and €3.0bn, respectively.
What is risk?
When talking about "increase in losses", it is important to distinguish the terms hazard and risk. While hazard is
the existence of a possibly dangerous natural phenomenon and the probability of an extreme manifestation of
that phenomenon, risk also looks at what may happen in that case. In the scientific community it is widely
agreed that risk is the product of a hazard and its consequences. Hence, three components determine the risk:
1. the hazard i.e. the threatening natural event including its probability of occurrence;
2. the exposure, i.e. the values/humans that are present at the location involved;
3. the vulnerability, i.e. the lack of resistance to damaging/destructive forces.
In its most simple form risk is computed by multiplying these three components.
From this definition follows that:
1. Where natural forces are gentle or where destructive events happen extremely seldom, the risk - in general - is
low.
2. Where there are no people or values that can be affected by a natural phenomenon, there is no risk. In a similar
way a disaster can only happen when people are harmed and/or their belongings damaged.
3. Where people are well prepared, the impacts of nature's forces may be kept at a low level; therefore, the risk
is low.
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