Noun
A wall or bank to hold water back.
An instrument for measuring or ascertaining the depth or quantity of water, or for indicating the height of its surface, as in the boiler of a steam engine. See Gauge.
Source: Webster's dictionarywater-gauge
The pitot tube can be inserted through a small hole in the duct with the pitot connected to a U-tube water gauge or some other differential pressure gauge for determining the flow velocity inside the ducted wind tunnel. Source: Internet
Low pressures such as natural gas lines are sometimes specified in inches of water, typically written as w.c. (water column) or w.g. (inches water gauge). Source: Internet