RRA
Data Products Physical Risk Flood Zone Encroachment Analysis

Physical Risk

Flood Zone Encroachment Analysis

Parcels on trajectory to enter FEMA Zone AE — projected encroachment horizon in years, derived from subsidence velocity, LiDAR ground elevation, and BFE contours.

14,676
At-Risk Parcels
1,274
Within 10 Years
2,814
Within 20 Years
107K+
Caddo Parcels

About this product

Current FEMA flood maps are static — they reflect zone boundaries as of their last revision date. This analysis asks a different question: given measured ground subsidence rates and current freeboard, which parcels are on trajectory to enter Zone AE before a 15- or 30-year obligation matures?

Three independently-sourced layers underlie each parcel's projected horizon: satellite-measured ground subsidence velocity, LiDAR-derived ground elevation and freeboard depth, and FEMA Base Flood Elevation contours. The output is a single number per parcel: years until Zone AE entry at the current subsidence rate — a risk conclusion, not a raw measurement.

Relevant to any institution with 15–30 year obligations in the region: mortgage originators, bond insurers, flood insurance underwriters, and municipal planners modeling infrastructure service life.

Buyers

  • Mortgage lenders underwriting long-term purchase loans
  • Bond insurers and GSEs with long-dated collateral exposure
  • Flood insurance underwriters (NFIP and private market)
  • Municipal planning and infrastructure departments

Delivery

  • ·CSV or GeoJSON, parcel-level for at-risk parcels only
  • ·Can be delivered as full dataset or filtered by horizon threshold
  • ·Coverage concentrated in parcels with Zone AE BFE contours; Zone X parcels are excluded (by definition they have no BFE reference point for encroachment calculation)
  • ·Quarterly refresh aligned to subsidence and LiDAR update cadence

Dataset Fields

geogno / parcel_id
Parcel identifier
velocity_vert_mmyr
Subsidence rate driving the encroachment calculation
ground_elev_ft
LiDAR-derived ground elevation at parcel centroid (USGS 3DEP 10m)
bfe_elev
FEMA Base Flood Elevation at parcel centroid
freeboard_ft
Current margin above BFE (bfe_elev − ground_elev_ft). Negative = already below BFE.
years_until_entry
Projected years until parcel ground elevation reaches BFE at current subsidence rate
confidence
'multi-track' or 'single-track' per InSAR input
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