Moab flooded. Most of the damage was outside the flood map.
Grand County collected 122 damage reports after the August 2022 flood in Moab. Laid over FEMA's 100-year floodplain, 105 of them fall outside it. One question, two public layers.
Moab flooded in August 2022, and Grand County collected damage reports from residents and businesses afterwards. The question at the table was whether FEMA's 100-year floodplain, the map flood insurance requirements are based on, described where the water actually went. NeuraCities put the two layers together in one pass.
How it got to 105 of 122
Two public layers and one join:
- 122 flood damage reports from Grand County's public damage layer. Each is a point with the type of property and the kind of damage.
- FEMA's special flood hazard areas from the National Flood Hazard Layer: the zones with a 1 percent chance of flooding in any year.
- A spatial join tagged every report as inside or outside those zones. 17 are inside and 105 are outside, drawn in blue and orange on the map with the split charted beside it.
Read the number carefully
The 122 are reports, not buildings. Some addresses filed more than one, and the reports sit at 89 distinct locations, 76 of them outside the floodplain. Outside does not mean far away either: 59 of the 105 are within 100 metres of the mapped zone. The next questions are one sentence each in the same conversation: how far outside, which streets, and what the same reports look like against the 500-year zone.
Moab Flood Damage vs Flood Map
Everything above is this conversation. Open it to see the sources, steps and layers, and ask the next question yourself.