Detailed risk analysis
Interactive Map
Instructions: Click the interactive map above to relocate the flood-risk map (right). You can also pan and zoom this map.
Explore flood risk (right) with controls below the map. Risk analysis is available only within the blue boundary on the map above.
Exceedance
We express "exceedance" (likelihood of flooding) as the expected number of floods per year. Exceedance can be less than 1. Some examples:
- exceedance = 10 floods/year = frequent flooding (expect 10 floods per year)
- exceedance = 1 floods/year = high risk (expect yearly flooding)
- exceedance = 0.1 floods/year = moderate risk (10% chance of a 10-year flood)
- exceedance = 0.01 floods/year = low risk (1% chance of a 100-year flood)
| color | flood risk | exceedance (floods/year) | description |
|---|---|---|---|
| frequent flooding | greater than 1 | expect more than one flood per year | |
| high risk | 0.1 - 1 | yearly flooding possible in worst case | |
| moderate risk | 0.01 - 0.1 | 1-10% chance of flood in a given year | |
| low risk | less than 0.01 | less than 1% chance of flood in a given year |