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Floodplain: assessment uses First Street (2020), we serve FEMA NFHL — pick one and document it #106

Description

@cboettig

Status: needs a decision from us. Not blocked on anyone; not a defect.

The situation

value
2025 Assessment flood source First Street Foundation (2020)
our source FEMA NFHL, SFHA_TF='T'
100-yr floodplain conserved, assessment 14%
100-yr floodplain conserved, ours 16.1%

Two defensible national floodplain products; a 2.1 pp difference in the answer. Nothing is broken — we simply do not serve the layer the assessment used, and the app does not say so.

Options

  1. Keep FEMA NFHL and document the difference in system-prompt.md, so the agent attributes the source correctly and does not present 16.1% as reproducing the assessment. Cheapest, and keeps the app on an open, redistributable source.
  2. Ingest First Street 2020 for exact parity. Previously deferred on access/licensing grounds, which have not been revisited since.

Recommendation: option 1, unless a partner specifically needs report parity on this row. First Street's licensing makes it a poor fit for a public app, and the honest framing ("we use FEMA NFHL; the assessment used First Street; here is the difference") is more useful to users than a number that silently matches.

Done when: either system-prompt.md carries the attribution note (option 1), or a focused ingest issue exists on data-workflows with the licensing question resolved (option 2).

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    questionFurther information is requestedvalidationReproducing the 2025 Biodiversity Assessment

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