Comprehensive, Global Flood Asset and Risk Mapping
Risks associated with extreme floods arise from a convergence of three factors.
First, extreme floods are usually connected to an anomalous movement of ocean moisture in the atmosphere. Second, the way that events are distributed in space and time in relationship to topography, soils, land use and other features concentrates water along natural drainage pathways that can lead to inundation of a particular area. Finally, the density and distribution of population and assets converges with natural factors to determine actual losses.
While there have been numerous studies on each of these individual factors, there have been relatively few attempts to integrate the three to develop a comprehensive global analysis of flood population and asset risk.
Columbia Water Center scientists are currently studying the intersection of climate, land surface features and population and assets to map global flood risk. Research will:
- Develop a quantitative approach to identify and relate the climate factors that lead to floods for specific regions of the world with high flood exposure and the potential for predictable floods;
- Develop a methodology to determine flood risk by overlying current population and asset data with historical records and reconstruction of extreme floods;
- Develop a model to project potential future flood impacts, integrating climate mechanism, general circulation models (GCMs) and population/asset projections regionally.
When it comes to natural disaster-related loss of life and property globally, floods dominate. But because of the potential magnitude and breadth of losses from a single flood event, many insurers have limited their risk exposure by refusing to insure against floods; in a given extreme event the number of claimants can be larger than the available pool of policyholders, which makes covering costs impossible. In the United States, this problem is addressed in part through a federal flood insurance program.
Nonetheless, better predictive models for assessing both flood timing and location and asset risks would allow for companies and governments to spread flood insurance risk more broadly, thus allowing both a reduction in premiums and a greater number of people to be insured.
The Columbia Global Flood Project is engaged in new research to address this issue. This research will focus on global mapping of correlated asset and flood risks, along with design of global risk pool instruments informed by new global flood prediction models.
Global Risk Management Pool
An examination of where large floods occur annually shows that extreme floods in some regions may be correlated with parallel drought in other regions. This observation is consistent with both the quasi-periodic nature of ENSO/PDO as well as the behavior of atmospheric rivers and other climate precursors to floods.
A global assessment of flood risk coupled with a map of assets at risk would, in a given year, allow for a calculation of the global maximum annual draw from the pool. Being able to estimate maximum payouts in a given year, while spreading risk would make such a financial mechanism both more effective and more affordable.
In such a system rich countries could subsidize a portion of poorer countries’ contribution to the pool. Doing so would be more cost effective and efficient than trying to help poor countries weather flood losses through after-the-fact disaster relief.