Any device that measures and records the height of the water at a station: floats in stilling wells, gas-purge and submerged pressure sensors, acoustic sensors in sounding tubes and downward-looking microwave radars. A gauge is only useful when its zero is tied by levelling to bench marks and checked against a tide staff, so a station is really the gauge plus its marks, levels and records.
Tide gauge on the pier went offline at 0300, so the survey's on the backup sensor until it's fixed.
A gauge record is only as good as its levelling history; a modest sensor that is regularly tied to its marks beats an expensive one that never is.
Also heard as
- water level gauge
- tide gage
- marigraph
- water level station
Related terms
Stilling well
An upright tube fed through a narrow bottom intake, filtering out waves so the gauge inside sees only the slow tide.
Bubbler
Field name for a gas-purge pressure gauge that measures water level by pushing gas through an underwater orifice.
Microwave radar sensor
A non-contact water level sensor mounted above the surface that measures the distance down to the water by radar.
Pressure gauge
A submerged sensor that measures the weight of water above it, converted to water level with density and air pressure.
Bench mark
A permanent, stable mark of known height near a tide station that preserves the station's datums.