| Additional details |
The FATHOM flood-hazard model is a global gridded dataset of flood hazard produced at the global scale. It provides flood extent and water depth to ground (in centimeters) for three types of flood phenomena:
- Fluvial (or river) flooding occurs when a river exceeds its capacity and inundates surrounding areas.
- Pluvial (or surface water) flooding occurs when extreme rainfall exceeds surface drainage capacity.
- Coastal flooding occurs when a combination of storm-surge, tides and waves lead to water levels that submerge the coastal land.
There are two options for each flood type: Defended and Undefended (fluvial and coastal only). Defended scenarios account for protection standards in proportion to country wealth to reduce the chance of hazard occurrence. It does not take account location-specific physical protection measures.
The model covers 4 time periods:
- 2020 (present baseline)
- 2030 (near future)
- 2050 (mid-century)
- 2080 (far future)
Future periods include 4 model realizations, each one describing a different climate scenario:
- SSP1 – 2.6 (limited emissions)
- SSP2 – 4.5
- SSP3 – 7.0
- SSP5 – 8.5 (high emissions)
Each scenario set is made of 10 events each representing a different intensity and probability of occurrence, expressed as “return period”. These are framed as 1 in 5, 10, 20, 50, 100, 200, 500 and 1,000 years. |