| Water allotment [WA] {ccf, m3} |
A method to accurately and fairly estimate a total volume of water that should be allocated to a site. (Predicting, 2000) |
| Water allotment adjustment factor [Kwa] {-} |
Factor used in the equation to predict Water allotment. (Predicting, 2000) |
| water application efficiency |
See efficiency. |
| water content (of soil sample) |
See soil-water content |
| water conveyance efficiency |
See efficiency. |
| water hammer {psi, kPa m} |
-- Phenomenon which occurs when the velocity of water flowing in pipelines is rapidly changed, usually by a rapid or sudden gate or valve closure, starting or stopping of a pump, or sudden release of air. The resulting pressure waves pass through the water at high velocities and can produce very high momentary positive and/or negative pressures. ANSI/ASAE S261.7 OCT96)
-- Shock wave created when the flow of water in a piping system suddenly stops (or changes speed). Usually the result of a fast-closing (or opening) valve. (Rain Bird, 1997) |
| water pressure |
See pressure. |
| water holding capacity {in./in., in./ft, mm/m } |
Total amount of water held in the soil per increment of depth. It is the amount of water held between field capacity and oven dry moisture level. (NRCS, 1997) |
| water horsepower (water power) |
See horsepower. |
| water meter |
Device used to measure to flow of water. |
| water rights |
State administered legal rights to use water supplies derived from common law, court decisions, or statutory enactments. (NRCS, 1997) |
| water storage efficiency |
See efficiency. |
| water table |
Upper surface of a saturated zone below the soil surface where the water is at atmospheric pressure. (NRCS, 1997) |
| water use efficiency |
See efficiency. |
| water window {h } |
Time of day available for irrigation to occur. (Rain Bird, 1997) |
| weir |
Flow measuring device for open-channel flow. Weirs can be either sharp-crested or broad-crested. Flow opening may be rectangular, triangular, trapezoidal (cipolletti), or specially shaped to make the discharge linear with flow depth (sutro weir). Calibration is based on laboratory ratings. (NRCS, 1997) |
| wet weight (of soil sample)* [WW] {lbs, grams}(11/6/99) |
Weight of soil sample and included soil moisture. (Reference Manual) |
| wetted area* [As, WA] {ft 2, m2} |
Surface area wetted at completion of irrigation. (Landscape, 1996) |
| wetted diameter |
Preferred term diameter of throw. |
| wetting agent |
Chemical used to reduce the surface tension of a liquid causing it to make better contact with the desired target. |
| wilting point [WP] |
See permanent wilting point. |
| winterization |
Process of removing water from the irrigation system before the onset of freezing temperatures. (Rain Bird, 1997) |
| wire gauge {-} |
(One of several) standard units of measure for wire size. The larger the gauge number, the smaller the wire. (Rain Bird, 1997) |
| work* {hp-h, kw-h} |
Work done by a force on a particle is defined as the product of the magnitude of the force and the distance through which the particle moves. (Physics, 1962). In hydraulic systems, it can be calculated as the product of the pressure and flow rate. brake Measure of work input into a pump or other device
water Measure of work output from a pump.
|
| working pressure {psi, pKa} |
Pressure of the irrigation system during operating. Synonymous with dynamic pressure. (Rain Bird, 1997) |
| working storage [WS] {in., mm} |
Amount of water available in the soil profile for plant use after consideration of MAD. (Landscape, 1996) Preferred term is Allowable Depletion [AD] |