Coastal boundary ambiguity

Global

Land/water boundary polygons vary by data vintage and mean-high-water definition; cells right at the coastline can flip land/water classification between sources.

Detection

Compare land-mask membership for the same cell across two boundary vintages/sources; flag disagreements.

Mitigation

Pin a single authoritative coastline source and vintage
Report a land-fraction confidence per coastal cell rather than a binary flag

Affected conversions

PolygonH3 (intersects)
Admin polygonsH3 (max-overlap partition)
RasterH3