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Hydro-terms visualized

A picture can be worth a thousand words, so we’ll let the pictures help us do the talking:

graphic showing gallons in a cubic foot

Cubic foot: instantaneous streamflow is often report in cubic feet per second. For reference, a cubic foot is about 7.5 gallons, so you can picture that many imaginary milk jugs flowing across a point in a second.


graphic showing volume of acre foot on football field

Acre-foot: when describing how much water flows past a streamgage during a day or month or year, it is easier to describe in terms of acre feet. An acre-foot is the amount of water that would cover a football field in one foot of water. If a hypothetical stream consistently flowed 1 cubic foot per second (cfs) for an entire year, that would be equal to about 724 acre-feet.