A pressure transducer fixed underwater, either on a structure or on the seabed, that records total pressure. Subtracting atmospheric pressure (by venting or a separate barometer) and dividing by water density and gravity gives the depth of water above it. Pressure gauges are cheap and easy to deploy for short-term stations and offshore sites, but they drift and cannot fix their own height, so staff readings or levelling tie them to datum.
Pressure gauge was unvented, so pull the barometer file from the pier and correct before you compare.
Seabed pressure gauges can settle into soft sediment, so a deployment without staff readings at both ends can hide a slow sinking trend.
Also heard as
- pressure sensor
- bottom pressure recorder
- submerged pressure gauge
Related terms
Bubbler
Field name for a gas-purge pressure gauge that measures water level by pushing gas through an underwater orifice.
Staff shot
A set of tide staff readings taken alongside the gauge to check that the gauge is still reading true.
Tide gauge
An instrument that records water level continuously at a fixed point, the basic tool of tidal measurement.
Inverse barometer effect
The rise of sea level under low air pressure and fall under high pressure, about 1 cm per hectopascal.