HOW IS WATER MEASURED?

Still or Flowing?

There are two considerations for water measurement.

• Is the water still, i.e., being stored in a lake, reservoir, or pond?
• Is the water flowing, i.e., in a ditch or pipeline.

Stored Water

For water that is still, the measuring units and measurement methods are those for typical liquid volume such as gallons, liters, and cubic feet or when volumes are large, acre feet.

• An acre foot is an acre (43,560 square feet) covered with water one foot deep.
• One acre foot is equivalent to 325,581 gallons.

 The measurement methods for still water are the typical methods to determine the height, width, and depth of the body of water.

Flowing Water

For water in motion, the measuring units simply consider the volume of water (as above) moving over time.

• The typical unit of measurement is cubic feet per second.

 In order to have a uniform method for this measurement, water managers use a Parshall Flume, a device inserted in the path of the flowing water.

• It has parallel sidewalls and a drop in the floor throat that accelerates the water through an exact set of dimensions.
• There are twenty-two different sizes of Parshall Flumes.
• Adjacent to the northern section of the Town’s Surface Creek walking trail, Cedaredge citizens can view a modest-sized Parshall Flume measuring water flow as it is diverted from Surface Creek into Alfalfa Ditch.
  • One cubic foot per second equals 7.4805 gallons flowing by a particular point in one second.
  • One cubic foot per second flow can deliver 448.8 gallons per minute, 1.983 acre feet or 646,320 gallons per day or 724 acre feet per year
  • 0.504 cubic feet per day can deliver one acre foot of water each day.
  • At one cubic foot per second, a person standing in the way would get hit by 62.4 pounds of weight every second.