Arc Hydro
Free
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NOAA VDatum
ActiveTransform elevations between vertical datums — the essential fix-up for US coastal flood and drainage models.
by NOAA
- Pricing
- Gov-Public
- License
- US Government (public domain)
- Commercial use
- Permitted
- Ecosystem
- Java, Browser, REST API
- Platform
- Web, Windows, macOS, Linux
About NOAA VDatum
VDatum converts elevation data among dozens of US vertical datums — orthometric (NAVD 88), ellipsoidal, and the full family of tidal datums (MLLW, MHHW and friends) — as a web tool, desktop application and API. Mixing datums is one of the classic silent errors in coastal work: a metre-scale offset between a lidar DEM on NAVD 88 and a storm-tide boundary on MLLW quietly corrupts every flood elevation downstream.
Any US project where terrain meets tide — coastal flood studies, outfall hydraulics, sea-level-rise screening — runs its data through VDatum at some point. Free, authoritative and maintained by NOAA's National Geodetic Survey and coastal services.
Where it fits in the workflow
TerrainCatchmentRainfallRunoffRoutingHydraulicsMappingReporting
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