Publication Date:
2019
Description:
Abstract
In this paper we seek to understand the nature of flood spatial dependence over the conterminous US. We extend an existing conditional multivariate statistical model to enable its application to this large and heterogenous region and apply it to a 40‐year data set of ~2,400 USGS gauge series records to simulate 1000 years of US flooding comprising more than 63,000 individual events with realistic spatial dependence. A continental‐scale hydrodynamic model at 30m resolution is then used to calculate the economic loss arising from each of these events. From this we are able to compute the probability that different values of US annual total economic loss due to flooding are exceeded (i.e. a loss‐exceedance curve). Comparing these data to an observed flood loss‐exceedance curve for the period 1988‐2017 shows a reasonable match for annual losses with probability below 10% (e.g. 〉 1 in 10 year return period). This analysis suggests that there is a 1% chance of US annual fluvial flood losses exceeding $78Bn in any given year, and a 0.1% chance of them exceeding $136Bn. Analysis of the set of stochastic events and losses yields new insights into the nature of flooding and flood risk in the US. In particular, we confirm the strong relationship between flood affected area and event peak magnitude, but show considerable variability in this relationship between adjacent US regions. The analysis provides a significant advance over previous national flood risk analyses as it gives the full loss‐exceedance curve instead of simply the average annual loss.
Print ISSN:
0043-1397
Electronic ISSN:
1944-7973
Topics:
Architecture, Civil Engineering, Surveying
,
Geography
