APN Flood Exposure Metric
One of five Substrate components. Measures flood-hazard presence per locality — the greatest value across all available state flood-hazard flag layers, inverted to a national percentile rank (100 = no flood-hazard flag present, most resilient).
Source: state/territory flood-hazard layers of varying quality — true 1% AEP hydraulic extents (VIC, ACT, WA), an evidence-based planning overlay (SA), a coarse statewide overlay (QLD), a sparse historical compilation (TAS), and a partial regulatory layer (NSW).
NSW: only ~12 of ~129 LGAs (11% of population) have any flood data at all — effectively unmeasured for 89% of the state, including every LGA in the top 8 by population. TAS: a sparse 2008-vintage compilation, 35 polygons nationally. NT: genuine structural NIL — no statewide flood data exists; NT carries no 24151 row at all. Per policy, low-confidence localities are still scored (not NIL’d) with their confidence flagged, rather than silently implying more certainty than the source supports.
QLD reclassified low-confidence, 29 Jul 2026 — a genuine finding, not a routine flag. An independent benchmark check against published Climate Council/Insurance Council of Australia data found QLD holds ~40% of Australia’s at-risk flood properties nationally and the highest state-level “uninsurable by 2030” rate (6.5%) of any state — yet QLD’s hit rate in this dataset (2.5%) was among the lowest of all built states. QLD’s source is a coarse 2013 statewide overlay explicitly not intended for parcel-level use; the benchmark check turned that quality caveat into concrete evidence the coarseness likely understates QLD’s true flood exposure.
Heavily concentrated at 100 (no flood-hazard flag present) — a direct consequence of the low hit rates documented above (0.1%–9.0% by state), not an indication that flood risk is rare nationally.
Alignment with the pillar. Across the 6,624 localities scored on both, this component and APN Substrate™ (Climate Resilience Rating) (24150) have a correlation of 0.65, on a scale where 1 means the two scores move together exactly and 0 means they are unrelated. The two are moderately aligned: a locality that scores high on this component tends to score above average on Substrate, with many exceptions. This component is one of the pillar’s five inputs, so part of that alignment is built into the pillar itself.
A state and territory comparison is not shown for this component. The flood-hazard layers behind it are compiled separately by each jurisdiction and differ in coverage, and no Northern Territory localities are scored, so state averages would reflect differences between source layers rather than differences in exposure.
The other four components of APN Substrate™ (Climate Resilience Rating) (24150).
- Flag-don’t-gate coverage policy applied
- QLD reclassified low-confidence via a cross-state benchmark check
