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Glossary of Irrigation Terms
Version 08/11/2006
The Irrigation Association®
6540 Arlington Blvd.
Falls Church, VA 22042-6638
USA
Edited by
Eugene W. Rochester,
CID
Certification Consultant
This document is in continuing development. You are
encouraged to submit definitions along with their source to the editor at the
address located at the end of this document (click here).
The terms in this Glossary are presented in an effort to provide a foundation
for common understanding in communications covering irrigation.
A * next to a term indicates variables and symbols that are
preferred for use in the Irrigation Association Education and Certification
programs. A date in small letters indicates the date when the Certification
Board approved the term. General definitions of terms not used in mathematical
equations are not flagged in any way. Quantitative terms have {units} indicating
sample units. Three dots (... ) at the end of a definition indicates that
the definition has been truncated. Terms with strike-through are non-preferred
usage. References are provided for the convenience of the reader and do
not infer original reference.
[ ] symbols located within bracket
indicates the IA preferred abbreviation of symbol for the term specified.
{ } symbols located within bracket
indicates the IA preferred units for the term specified.
See notes at the end of this document relative to
metric/SI/Australian units (click here).
A
AC [] {hertz} abbreviation for alternating current.
AC pipe [] Asbestos-cement pipe was commonly used for
buried pipelines. It combines strength with light weight and is immune to
rust and corrosion. (James, 1988) (No longer made.)
acceleration of gravity. See gravity,
acceleration of.
acid [] Substance with a pH less than 7.0 (Burt, 1998)
adhesion [] {}
- Attraction of water molecules for solid surfaces. (Brady, 1990)
- Physical attraction of unlike substances to one another. In soils,
it is the process that holds water molecules tightly to soil solids at the
soil-water interfaces. (Contractor, 1999)
adjusted sodium adsorption ratio [adj. RNa] {} Index
of permeability problems, based upon water quality. (Burt, 1998)
adsorption [] {} Concentration of a substance at
the surface of another, more noticeable with substances of large surface area,
such as clay particles. (Hess, 1999)
advance ratio [AR] {-} Ratio of the time for the water to reach
the end of the field to the total set time for an irrigation set on a furrow
irrigation system. The ratio should be less than 0.5 to have a good
distribution uniformity. (Burt, Surface Irrigation)
advance time [] {minutes, sec}
- Time required for a given stream of irrigation water to move from the
upper end of a field to the lower end. (ASAE, 1998)
- Time required for a given surface irrigation stream to move from one point
in the field to another. (NRCS, 1997)
aeration [] To supply or impregnate with air. (Webster, 1981)
aeration capacity [] {-} Volume fraction of air filled pores in
a soil at field capacity. (Hess, 1999)
aggregate []
- Group of primary soil particles that cohere to each other more strongly
than to other surrounding particles. (Soil, 1996)
- Groups of individual soil particles, held together naturally and
consisting of particles of sand, silt and clay separated from each other by
pores, cracks or planes of weakness. The term, soil structure, refers
to this arrangement of the soil in natural aggregates. Various types of soil
structure are recognized (Massive, platy, prismatic, blocky, granular).
air gap: See
back flow prevention device.
alfalfa valve [] Outlet valve attached to the top of a pipeline
riser with an opening equal in diameter to the inside diameter of the riser pipe
and an adjustable lid or cover to control water flow... (ASAE, 1998)
algicide [] Substance that will kill or control algae growth.
(NRCS, 1997)
alkaline (alkali) soils []
- Soil with pH greater than 7.0. (Soil, 1996)
- Soil with an exchangeable sodium percentage greater than 15%. (Burt, 1998)
- Soil that has sufficient exchangeable sodium (alkali) to interfere with
plant growth and cause dispersion and swelling of clay minerals...
Hess, 1999
allowable depletion* [AD] {in.,mm}(7/19/03)
- Portion of plant available water that is allowed for plant use prior to
irrigation based in plant and management considerations. See
Fig. 1 at end of document.
- That part of soil moisture stored in the plant root zone managed for use
by plants, usually expressed as equivalent depth of water in acre inches per
acre, or inches. (NRCS, 1997)
- Is sometimes referred to as allowable soil depletion or
allowable soil water depletion.
allowable stress factor: See
coefficient.
allowable voltage loss* [AVL] {volts}
- Voltage loss in a circuit or portion of a circuit which, if not exceeded,
will result in the electrical device working correctly.
alternate set irrigation: See
irrigation systems.
alternating current [AC] {} Current in which the flow of
electrons in a circuit flow in one direction and then in the reverse direction.
(Reference Manual ch. 5)
ampere* [] {ampere or amp} (approved via RM)
- Unit of electrical current. The unit is used to specify the movement
of electrical charge per unit time through a conductor. (Pumps, 1996)
- 1 ampere = 1 coulomb per second.
- 1 ampere is the movement of 6.28 billion billion electrons /second.
anion [] Negatively charged ion, which during electrolysis is
attracted towards the anode. The most common anions in soil extracts and
waters are bicarbonate, sulphate, carbonate, chloride and nitrate ions. (Hess,
1999)
application efficiency: See
efficiency.
application efficiency of lower quarter: See
efficiency.
application efficiency low half: See
efficiency.
application rate: See
precipitation rate.
aquifer [] Underground geological formation,
or group of formations, containing usable amounts of groundwater that can supply
wells or springs for domestic, industrial, and irrigation uses. Removing more
groundwater from an aquifer than is naturally replenished is called
overdrafting, and can result in a dropping water table, increased pumping costs,
land subsidence (which reduces the future recharge capacity), saltwater
intrusion, reduced streamflows in interconnected ground- and surface-water
systems, and exhaustion of groundwater reserves. Overdrafting groundwater occurs
primarily in the Plains States and the West. (Agriculture, 1997)
arc [] {degrees} Portion of a full circle (360 )
covered by a part circle sprinkler.
area* [A] { in.2, ft2,acres,ha} (7/19/03)
Surface included within a set of lines (Webster). In irrigation, usually used to
describe a surface of land or cross section of pipe.
arid climate: See climate.
atmospheric pressure* [Pa] {psi, , ft water,
atmospheres, kPa} (7/19/03) Absolute pressure measured at any location.
Standard atmospheric pressure at sea level is defined as 14.7 psi or 34.0 ft of
water.
atmospheric vacuum breaker: See
backflow prevention device.
automatic drain valve: See valve.
available soil moisture [ASM] {in.,mm}(7/19/03) Difference at
any given time between the actual soil moisture content in the root zone soil
and the wilting point. (On-Farm Committee, 1979)
available soil moisture capacity [AMC] See available
water.
available water *[AW ] {%, in./ft, mm/mm } ((7/19/03))
- Portion of water in a soil that can be readily absorbed by plant roots.
It is the amount of water released between in situ field capacity and the
permanent wilting point. (ASAE, 1998) See
Fig. 1 at end of document. See also available water holding
capacity.
available water holding capacity [AWHC] {in./ft, mm/mm}
Preferred term is available water.
available water storage capacity [AWSC] {in./ft, mm/mm}:
Preferred term is available water.
average annual precipitation [] {in., mm} Long-term
historic (generally 30 years or more) arithmetic mean of precipitation (rain,
snow, dew) received by an area. (NRCS, 1997)
AVB: See
atmospheric vacuum breaker
under
backflow prevention devices.
B
back flow [] Any unwanted flow
of used or non-potable water or substance from any domestic, industrial or
institutional piping system into the pure, potable water distribution system.
The direction of flow under these conditions is in the reverse direction from
that intended by the system and normally assumed by the owner of the system.
(USC, 1998)
backflow prevention device
[BPD] Safety device which prevents the flow of water from the water
distribution system back to the water source (ASAE, 1998)
- air gap Physical separation of the supply pipe
by at least two pipe diameters (never less than one inch) vertically above
the overflow rim of the receiving vessel. In this case line pressure is
lost. Therefore, a booster pump is usually needed downstream, unless the
flow of the water by gravity is sufficient for the water use. With an air
gap there is no direct connection between the supply main and the equipment.
An air gap may be used to protect against a contaminant or a pollutant, and
will protect against both back-siphonage and backpressure. An air gap is the
only acceptable means of protecting against lethal hazards. . (USC, 1998)
- atmospheric vacuum breaker
[AVB]
- Backflow device configured with a single moving part, a float, which
moves up or down to allow atmospheric air into the piping system.
(Rochester, 1995)
- The AVB is always placed downstream from all shut-off valves. Its air
inlet valve closes when the water flows in the normal direction. But, as
water ceases to flow the air inlet valve opens, thus interrupting the
possible back-siphonage effect. If piping or a hose is attached to this
assembly and run to a point of higher elevation, the backpressure will keep
the air inlet valve closed because of the pressure created by the elevation
of water. Hence, it would not provide the intended protection. Therefore,
this type of assembly must always be installed at least six (6) inches above
all downstream piping and outlets. Additionally, this assembly may not have
shut-off valves or obstructions downstream. A shut-off valve would keep the
assembly under pressure and allow the air inlet valve (or float check) to
seal against the air inlet port, thus causing the assembly to act as an
elbow, not a backflow preventer. The AVB may not be under continuous
pressure for this same reason. An AVB must not be used for more than twelve
(12) out of any twenty-four (24) hour period. It may be used to protect
against either a pollutant or a contaminant, but may only be used to protect
against a back-siphonage condition. . (USC, 1998)
- double check assembly [DC]
- Two internally loaded, independently operating check valves together
with tightly closing resilient seated shut-off valves upstream and
downstream of the check valves. Additionally, there are resilient seated
test cocks for testing of the assembly. The DC may be used to protect
against a pollutant only. However, this assembly is suitable for protection
against either backsiphonage or backpressure. (USC, 1998)
- pressure vacuum breaker [PVB]
- Backflow device configured with a spring loaded float and an independent
spring loaded check valve. (Rochester, 1995)
- Check valve which is designed to close with the aid of a spring when
flow stops. It also has an air inlet valve which is designed to open when
the internal pressure is one psi above atmospheric pressure so that no
non-potable liquid may be siphoned back into the potable water system. Being
spring loaded it does not rely upon gravity as does the atmospheric vacuum
breaker. This assembly includes resilient seated shut-off valves and test
cocks. The PVB must be installed at least twelve (12) inches above all
downstream piping and outlets. The PVB may be used to protect against a
pollutant or contaminant, however, it may only be used to protect against
backsiphonage. It is not acceptable protection against backpressure.
(USC, 1998)
- reduced pressure principle assembly [RP, RPA, RPZ]
Consists of two internally loaded independently operating check valves and a
mechanically independent, hydraulically dependent relief valve located
between the check valves. This relief valve is designed to maintain a zone
of reduced pressure between the two check valves at all times. The RP also
contains tightly closing, resilient seated shut-off valves upstream and
downstream of the check valves along with resilient seated test cocks. This
assembly is used for the protection of the potable water supply from either
pollutants or contaminants and may be used to protect against either
backsiphonage or backpressure. (USC, 1998)
back pressure []
- Increase of pressure in the downstream piping system above the supply
pressure at the point of consideration which would cause, or tend to cause,
a reversal of the normal direction of flow. (ASAE, 1998)
back siphonage []
- Reversal of flow (backflow) due to a reduction in system pressure which
causes a negative or sub-atmospheric pressure to exist at a site in the
water system. (ASAE, 1998)
- Technically, if one siphons a fluid out of a container or a pipeline, one
causes that fluid to flow up over the rim of the container or top of the
pipe and then down into a lower elevation through a piece of tubing or, in
this case a piece of pipe that is part of the distribution system. In the
vernacular, the unwanted fluid is "sucked" into the potable water line. It
is important to understand that it is not necessary for the system main to
be under a true vacuum (i.e., zero psia) for backsiphonage to occur. All
that is required is a negative difference in pressure and a piece of tubing
or pipe that is completely full of fluid. (USC, 1998)
basic intake rate: See intake
rate.
basin irrigation: See
irrigation systems
beneficial uses: See uses.
best efficiency point: See
efficiency.
best management practice [BPM] {} An irrigation BMP is a
voluntary irrigation practice that is both economical and practical and is
designed to reduce water consumption and protect water quality while maintaining
a healthy, functional landscape. (John Ossa, Committee Chair, IA Water
Management Committee. Nov. 2000)
black water [] Water containing liquid and solid human body
waste generated through toilet usage. (ASAE, 1998)
Blaney-Criddle Method [] Air temperature based method to
estimate crop evapotranspiration. (NRCS, 1997)
bog coefficient* [BC] {-}
- Inverse of scheduling coefficient but using the wettest 1%window instead
of the driest. Gives no indication of the location of dry areas.
(Contractor, 1999)
border dike [] Earth ridge or small levee built to guide or
hold irrigation or recharge water in a field. (ASAE, 1998)
border ditch [] Small excavation used as a border of an
irrigated strip or plot with water being spread from one or both sides. (ASAE,
1998)
border irrigation: See
irrigation systems.
brake horsepower: See
horsepower.
brake horsepower hour: See work.
British thermal units [] {BTU} Amount of heat required to raise
the temperature of one pound of water from 63 to 64 degrees Fahrenheit. ...
(Pumps, 1996)
bubbler [] Water emission device that tends to bubble
water directly to the ground or that throw water a short distance, on the order
of one foot, (300 mm) before water contacts the ground surface. (Smith, 1997)
bubbler irrigation: See
irrigation systems.
bulk density (of soil)*[Is,BDsoil] {lb/ft3}{g/cc}(11/6/99)
- Mass of dry soil per unit bulk volume ... (generally ranging in value from
1.3 to 1.6 g/cc) (ASAE, 1998)
(bulk) density of water* [Iw,
BDwater] {lb/ft3}{g/cc}(11/6/99) Same as
density of water.
- Mass of water per unit bulk volume. (approximately 1.0 g/cc, 62.4
lb/ft3)
C
cable tow traveler: See
irrigation systems.
cablegation: See irrigation
systems.
capillary radius [Cr] {ft, mm} Additional wetted
radius in soil profile beyond surface wetted radius for point source emitters.
(Landscape, 1996)
capillary water [] Water held in the capillary, or small pores
of the soil, usually with soil water pressure (tension) greater than 1/3 bar.
Capillary water can move in any direction. (NRCS, 1997)
carryover soil moisture [] {in., mm} Moisture stored in
the soil within the root zone during the winter, at times when the crop is
dormant, or before the crop is planted. This moisture is available to help
meet water needs of the next crop to be grown. (NRCS, 1997)
catch can grid [] Containers spaced at regular intervals for
collecting water for use in a water audit (sprinkler profile test). (Contractor,
1999).
cation [] Positively charged ion which during electrolysis is
attracted towards the cathode. Sodium, potassium, calcium and magnesium
are the most common cations in waters and soil extracts. (Hess, 1999)
cation exchange capacity*
[CEC] {cmol/kg}
- The measure of the positively charged ions in a soil matrix. (Fertility
and Fertilizers)
- The sum of exchangeable cations (usually Ca, Ma, K, Na, Al, H) that
the soil constituent or other material can adsorb at a specific pH, usually
expressed in centimoles of charge per Kg of exchanger (cmol/Kg), or milli
equivalents per 100 grams of soil at neutrality (pH = 7.0), meq/100g. (NRCS,
1997)
cavitation []
- Process when pressure on a liquid falls momentarily below the vapor
pressure of that liquid, causing a phase change from liquid to vapor, and
then a pressure increase causes another phase change and the gas becomes a
liquid again. (Richard Neff, 2000, unpublished)
- Process where pressure in the suction line falls below the vapor pressure
of the liquid, vapor is formed and moves with the liquid flow. These
vapor bubbles or "cavities" collapse when they reach regions of higher
pressure on their way through pumps. (Pumps, 1998)
CEC: See cation
exchange capacity.
center pivot irrigation: See
irrigation systems.
centrifugal pump : See pumps.
Certified Agricultural Irrigation Specialist (CAIS) The
Certified Agricultural Irrigation Specialist is involved in the management and
operation of on-farm irrigation systems. These systems include surface
irrigation methods, as well as pressurized systems like micro-irrigation and
sprinklers. Prior to certification examination, specialists are required to take
an Irrigation Association approved preparatory course. (IA Water Management
Committee, 2004)
Certified Golf Irrigation Auditor (CGIA) The Certified Golf
Irrigation Auditor is involved in the analysis of turf irrigation water use
tailored to the unique conditions found on golf courses. Golf Auditors collect
site data, make maintenance recommendations and perform water audits on golf
courses. Through their analytical work at the site, these irrigation
professionals develop base schedules for greens/tees, fairways and roughs. Prior
to certification examination, auditors are required to take an Irrigation
Association approved preparatory course. (IA Water Management Committee, 2004)
Certified Irrigation Contractor (CIC) The Certified Irrigation
Contractor is an irrigation professional whose principle business is the
execution of contracts and subcontracts to install, repair and maintain
irrigation systems. The CIC must conduct business in such a manner that
projects meet the specifications and requirements of the contract. (IA Water
Management Committee, 2001)
Certified Irrigation Designer (CID) The IA Certified Irrigation
Designer engages in the preparation of professional irrigation designs.
They evaluate site conditions and determine net irrigation requirements based on
the needs of the project. The designer is then responsible for the
selection of the most effective irrigation equipment and design methods.
The objective of a CID is to establish specifications and design drawings for
the construction of an irrigation project. (IA Water Management Committee, 2001)
Certified Landscape Irrigation Auditor (CLIA) The Certified
Landscape Irrigation Auditor is involved in the analysis of landscape irrigation
water use. Auditors collect site data, make maintenance recommendations
and perform water audits. Through their analytical work at the site, these
irrigation professionals develop monthly irrigation base schedules. Prior
to certification examination, auditors are required to take an Irrigation
Association approved preparatory course. (IA Water Management Committee, 2001)
Certified Landscape Irrigation Manager (CLIM) The Certified
Landscape Manager is an irrigation professional familiar with all areas of turf
irrigation design and construction management. CLIMs must be certified as CICs,
CID (all Landscape/Turf specialty areas), and either as a CLIA or CGIA.
Certified Landscape Irrigation Managers have extensive experience in design,
construction, construction management and auditing of turf irrigation systems.
(IA Water Management Committee, 2001, 2004)
check, check structure [] Structure to control water depth in a
canal, ditch or irrigated field. (NRCS, 1997)
check basin irrigation: See
irrigation systems.
check irrigation: See
irrigation systems.
check valve [] See valve, check.
chemigation [] Application of chemicals (including fertilizers)
to crops through an irrigation system by mixing them with the irrigation water.
(ASAE, 1998)
Christiansen's uniformity coefficient: See
uniformity coefficient.
circular mil *[CM] {circular mils} (approved via RM)
- Unit of measure used to report the cross sectional area of a wire
conductor (Reference Manual, ch. 5)
class (pipe) []
- Term generally used to describe the pressure rating of SDR-PR (standard
dimension ratio-pressure rated) PVC pipe. For example, a class 200 pipe has
a pressure rating of 200 psi. (colloquial)
- Term used to identify the physical characteristics of thermoplastic pipe.
(ASTM standard D1784-81)
class, soil [] Group of soils defined as having a specific
range in one or more particular properties such as acidity, degree of slope,
texture, structure, land- use capability, degree of erosion, or drainage. (Soil,
1996)
clay []
- Soil separate consisting of particles less than 0.002 mm in equivalent
diameter. (Brady, 1990; Soil, 1996)
- Soil textural class. (Soil, 1996)
- Naturally occurring material composed primarily of fine-grained minerals,
which is generally plastic at appropriate water contents and will harden
when dried or fired. ... (Soil, 1996)
clay loam [] Soil textural class. See also
texture, soil. (Soil, 1996)
climate []
- arid climate. Climate characterized by low rainfall and high
evaporation potential. A region is usually considered as arid when
precipitation averages less than 10 inches per year. (NRCS, 1997)
- humid climate. Climate characterized by high rainfall
and low evaporation potential. A region generally is considered as
humid when precipitation averages more than 40 inches per year. (NRCS, 1997)
- semiarid climate. Climate characterized as neither entirely
arid nor humid, but intermediate between the two conditions. A region
is usually considered as semiarid when precipitation averages between 10 and
20 inches per year. (NRCS, 1997)
- subhumid climate. Climate characterized by moderate rainfall
and moderate to high evaporation potential. A region is usually
considered subhumid when precipitation averages more than 20 inches per
year, but less than 40 inches per year. (NRCS, 1997)
coarse sand []
- Coarse sand is a soil separate. Its physical size varies according
to the classification system being utilized. (Brady, 1990; Soil, 1996)
- Soil textural class. (Soil, 1996)
coarse sandy loam [] Soil textural class. (Soil, 1996)
coefficient [k, K] {-} Various forms
of "k" are used to describe constants, coefficients and factors.
- allowable stress factor *[Kas] {-}
- Coefficient used to modify reference evapotranspiration to reflect the
water use of a particular plant or group of plants particularly with
reference to the water stress. (paraphrased from Landscape, 1996)
- Ratio of the actual crop evapotranspiration to it potential (or reference)
evapotranspiration. (NRCS, 1997)
- crop coefficient* [Kc] {-}(11/6/99)
- Coefficient used to modify reference evapotranspiration to reflect
the water use of a particular plant or group of plants particularly with
reference to the plant species.
- Ratio of the actual crop evapotranspiration to its potential (or
reference) evapotranspiration. (NRCS, 1997)
- density factor *[Kd] {-} ](approved via RM)
Coefficient used to modify reference evapotranspiration to reflect the
water use of a particular plant or group of plants particularly with
reference to the density of the plant material. (paraphrased from
Landscape, 1996)
- landscape coefficient *[KL] {-} (approved via RM)
Coefficient used to modify reference ET which includes species factor,
density factor and microclimate factor. (Landscape, 2000)
- microclimate factor* [Kmc] {-} (approved via RM)
Factor or coefficient used to adjust reference evapotranspiration to reflect
the microclimate of an area. (paraphrased from Landscape, 1996)
- pan coefficient [ ] {} Factor to relate actual
evapotranspiration of a crop to the rate water evaporates from a free water
surface in a shallow pan. The coefficient usually changes by crop
growth stage. (NRCS, 1997)
- species factor* [Ks] {-} (approved via RM) Factor
or coefficient used to adjust reference evapotranspiration to reflect plant
species. (Landscape, 1996)
coefficient, consumptive use [ICUC][{%} Ratio of volume
of irrigation water consumptively used to the total volume of irrigation water
that has left the region, both in a specified period of time. (Burt et al, 1997)
coefficient of retardation* [C, f] {-} (approved via RM) Values
describing the hydraulic frictional characteristics of a pipe material.
coefficient of runoff [C] {-} Runoff coefficient used in the
rational method of predicting a design peak runoff rate. It helps to
characterize runoff rate from a watershed area. (Schwab, et al., 1993)
coefficient of manufacturing variation: See
manufacturer's coefficient of
variation.
Coefficient of uniformity: See
Uniformity coefficient
[] cohesion
- Attraction of water molecules to each other. (Brady, 1990)
- Bonding strength between soil particles. (Hess, 1999)
- Attraction of like substances to one another. In soils, it is the
process that forms a film of water around soil solids. (Contractor, 1999)
compensating emitter: See
emitter.
consumptive use: See uses.
continuous-flow irrigation [] System of irrigation water
delivery where each irrigator receives the allotted quantity of water
continuously. (ASAE, 1998)
continuous flushing emitter: See
emitter.
control structure [] Water regulating structure, usually for
open channel flow conditions. (NRCS, 1997)
controller [] {}
- An electric timing device that operates each (irrigation) zone for a
predetermined time and frequency. (Keesen, 1995)
- An automatic timing device that sends an electric signal for automatic
valves to open or close according to a set irrigation schedule.
(Reaves, Lower Colorado River Authority.)
conveyance efficiency: See
efficiency.
conveyance loss [] {? ft3}
Loss of water from a channel or pipe during transport, including losses due to
seepage, leakage, evaporation, and transpiration by plants growing in or near
the channel. (ASAE, 1998)
corporation stop (valve): See
valve.
corrugation irrigation: See
irrigation systems.
coupler (sprinkler) [] Device, either self-sealed or
mechanically sealed, that connects the ends of two lengths of pipe or pipe to a
hose. (ASAE, 1998)
crop coefficient: See
coefficient.
crop evapotranspiration: See
evapotranspiration.
cross connection [] Any actual or potential connection or
structural arrangement between a public or private potable water system and any
other source or system through which it is possible to introduce into any part
of the potable system any used water, industrial fluids, gas, or substance other
than the intended potable water with which the potable system is supplied.
By-pass arrangements, jumper connections, removable sections, swivel or
change-over arrangements or other "temporary" arrangements through which
backflow could occur are considered to be cross-connections. (USC, 1998)
See also backflow.
crop growth stages [] Periods of like plant function during the
growing season. Usually four or more periods are identified (NRCS, 1997):
- Initial- Between planting or when growth begins and
approximately 10 percent ground cover.
- Crop development- Between about 10 percent ground cover and
70 or 80 percent ground cover.
- Mid season- From 70 or 80 percent ground cover to beginning
of maturity.
- Late- From beginning of maturity to harvest.
crop rooting depth: See root
zone.
crop water stress index [CWSI] {-} Index of moisture in a
plant compared to a fully watered plant, measured and calculated by a CWSI
instrument. Relative humidity, solar radiation, ambient air temperature,
and plant canopy temperature are measured. (NRCS, 1997)
crop water use: Same as
plant water requirement and
evapotranspiration.
cumulative intake [] {in.,mm} Depth of water absorbed by
soil from the time of initial water application to the specified elapsed time.
(NRCS, 1997)
curb stop (valve): See valve.
current *[I] {amperes, amps} (11/6/99)
- Movement or flow of electrons. (Derryberry, 1994).
- The flow of electrons in a conductor. (Reference Manual)
cutback irrigation: See
irrigation systems / furrow.
cycle time [] {min, h} Length of water application periods,
typically used with surge irrigation. (NRCS, 1997)
D
deep percolation* [DP] {in., mm}
- Movement of water downward through the soil profile below the root zone
that cannot be used by plants. (ASAE, 1998)
- Infiltrated water, which moves below the root zone. (Burt et al, 1997)
deficit irrigation [] Irrigation water management
alternative where the soil in the plant root zone is not refilled to field
capacity in all or part of the field. (NRCS, 1997)
deep percolation percentage [DP] {%} Ratio of the average depth
of irrigation water infiltrated and drained out of the root zone to the average
depth of irrigation water applied. (ASAE, 1998)
degree of hazard [] The type of backflow preventer used
to prevent backflow from occurring at the point of a cross-connection depends on
the type of substance which may flow into the potable water supply. A pollutant
is considered to be any substance which would affect the color or odor of the
water, but would not pose a health hazard. This is also considered a non-health
hazard. A substance is considered a health hazard if it causes illness or death
if ingested. This health hazard is called a contaminant. (USC, 1998)
delivery box (irrigation) []
- Structure diverting water from a canal to a farm unit often including
measuring devices. Also called "turnout". (ASAE, 1998)
- Water control structure for diverting water from a canal to a farm unit
often including a measuring device. Also called delivery site,
delivery facility, and turnout. (NRCS, 1997)
delivery loss: Preferred term is
conveyance loss.
demand irrigation( system )(delivery) [] Procedure where
each irrigator may request irrigation water in the amount needed and at the time
desired. (ASAE, 1998)
density (of water)* [Iw]
{g/cc, lb/ft3} Mass of water per unit volume. Same as
bulk density of water.
density factor: See coefficient.
densogram []
- Pattern of dots that shows the expected coverage from a particular
combination of sprinklers, nozzles, pressure and spacing. (Solomon, 1988)
- Graphical representation of precipitation rates. ... (Contractor,
1999)
depth* [d, D] {in., mm} (11/6/99) General term relating
to depth of soil, water, or similar.
depth of irrigation [] {acre inches per acre, in., ft, mm}
- Depth of water applied
- Depth of soil affected by an irrigation event. (NRCS, 1997)
diameter* [D, d] {in., mm}(11/6/99)
- Dimension / size of a circular pipe, usually but not always the inside
diameter [ID].
- inside diameter [ID, D] {in.} (approved via RM)
- outside diameter [OD, D] {in.}
- Nominal diameter (ND is, mm)
diameter of throw *
[Dt] {ft, m} (11/6/99) Average diameter of the area wetted by an
irrigation sprinkler operating in still air. (ASAE, 1998)
dielectric union [] Pipe connection (union) having an
insulator between the two sides of the union for the purpose of reducing
corrosion caused by galvanic action. (Smith, 1997)
dimension ratio* [DR] {-} Ratio of the average pipe diameter to
the minimum wall thickness. The pipe diameter may be either outside or
inside diameter. (ASAE, 1998) See related term
standard dimension ratio.
direct current [DC] {} Current in which electrons flow
constantly in one direction. (Reference Manual, ch 5)
distribution system [] System of ditches, or conduits and
their controls, which conveys water from the supply canal to the farm points of
delivery. (ASAE, 1998)
distribution uniformity*
[DU] {%, decimal} (11/6/99)
- Measure of the uniformity of irrigation water over an area. (ASAE, 1998).
distribution uniformity of lower quarter* [DUlq] {%,
decimal}
- Ratio of the average low quarter depth of irrigation water infiltrated to
the average depth of irrigation water infiltrated. (On-Farm Committee,
1979)
- Ratio of the average of the lowest one-fourth of measurements of
irrigation water infiltrated (or applied) to the average depth of (the
total) irrigation water infiltrated (applied). (ASAE, 1998)
disturbed (manipulated) soils []
Soils with soil profiles that have been altered because of earth-moving
activities (or soil amendment). (Contractor, 1999)
diversion box [] Structure built into a canal or ditch
for dividing the water into predetermined portions and diverting it to other
canals or ditches. (ASAE, 1998)
diversion dam [] Barrier built in a stream for the
purpose of diverting part or all of the water from the stream into a canal.
(ASAE, 1998)
double check valve assembly: See
backflow prevention device.
drip irrigation: See
irrigation system, drip.
drought [] Period of dryness especially when prolonged
that causes extensive damage to crops or prevents their successful growth.
(Webster's Collegiate Dictionary 10th Edition)
dry weight (of soil sample) *[DW] {lbs} {grams} (11/6/99) Oven
dry weight of a soil sample. (Reference Manual)
ductile iron [] Form of iron used to make pipe and
fittings.
dynamic head . See head,
dynamic.
dynamic pressure [] {psi, kPa} Measure of water pressure with
the water in motion (also known as working pressure). (Monroe, 1993)
E
effective precipitation
[Pe, ] {in., mm} Portion of total precipitation which becomes
available for plant growth. (ASAE, 1998)
effective rainfall [] {in., mm} Portion of total rainfall
which becomes available for plant growth.. (ASAE, 1998)
effective rooting depth: See
rooting depth, effective.
efficiency [E] {%, fraction} (11/6/99)
- application efficiency* [Ea, AE] (approved via
RM)
- Ratio of the average depth of the irrigation water stored in the root
zone to the average depth of irrigation water applied. (On-Farm
Committee, 1979)
- Ratio of the average depth of irrigation water infiltrated and stored in
the root zone to the average depth of irrigation water applied. (NRCS, 1997)
- Amount of water stored in the root zone that is available for plant use
divided by the average amount of water applied during an irrigation.
(Scheduling, 1998)
- Ratio of the average depth of irrigation water contributing to target,
to the average depth of irrigation water applied. (Burt, et al, 1997)
- (water) application efficiency of lower half* [Eh,
] Ratio of the average of the lowest one-fourth of measurements of
irrigation water infiltrated to the average depth of water applied. (NRCS,
1997)
- (water) application efficiency of lower quarter* [Eq,
]
- Ratio of the average low quarter depth of irrigation water infiltrated
and stored in the root zone to the average depth of irrigation water
applied. (On-Farm Committee, 1979)
- Ratio of the average of the lowest one-fourth of measurements of
irrigation water infiltrated to the average depth of water applied. (NRCS,
1997)
- best efficiency point [BEP] Highest efficiency on a pump
characteristic curve. (Pumps, 1998)
- conveyance efficiency* [Ec] Ratio of the water
delivered, to the total water diverted or pumped into an open channel or
pipeline at the upstream end. (NRCS, 1997)
- irrigation efficiency* [Ei, IE]
Ratio of the average depth of irrigation water that is beneficially used to
the average depth of irrigation water applied ... (ASAE, 1998)
(On-Farm Committee, 1979)
- potential application efficiency of Low Quarter [PELQ] {%)
low quarter application efficiency obtainable with a given irrigation system
when the depth of irrigation water infiltrated in the quarter of the area
receiving the least water equals some predetermined value of the soil
moisture deficit. (On-Farm Committee, 1979)
- pumping plant efficiency (overall) [Epp] {%} is the ratio of
the output power into the water to the input power to the driver. (ITRC,
2001)
- motor efficiency* [Em] Ratio of the power
delivered to the pump by the power unit to the input power to the motor.
- project efficiency [] Overall efficiency of irrigation water
use in a project setting that accounts for all water uses and losses, such
as crop ET, environmental control, salinity control, deep percolation,
runoff, ditch and canal leakage, phreatophyte use, wetlands use, operational
spills, and open water evaporation. (NRCS. 1997)
- pump efficiency* [Ep] Ratio of the water power
produced by the pump, to the power delivered to the pump by the power unit.
(ASAE, 1998)
- (water) storage efficiency* [] Ratio of the amount of
water stored in the root zone during irrigation to the amount of water
needed to fill the root zone to field capacity. (James, 1988)
- water use efficiency [WUE] Ratio of the yield per unit area
to the applied irrigation water per unit area. (Styles, S., 1999.
Unpublished)
effluent irrigation [] Land application of treated
wastewater for irrigation and beneficial use of nutrients. (ASAE, 1998)
electrical conductivity*[EC] {mmho/cm, dS/m}Measure of the
ability of the soil water to transfer an electrical charge. Use as an
indicator for the estimation of salt concentration.
- [ECe] Electrical conductivity of soil water extract.
- [ECi] Electrical conductivity of irrigation water.
- [ECaw] Electrical conductivity of applied water. (NRCS,
1997)
electrical resistance block [] Block made up of various
materials containing electrical contact wires that is placed in the soil at
selected depths to measure soil moisture content (tension). Electrical
resistance, as affected by moisture in the block is read with a meter. (NRCS,
1997)
elevation head: See head.
emission point [] Location where water is discharged from
an emitter. (ASAE, 1998)
emission uniformity *[EU] {-,%} Index of the uniformity of
emitter discharge rates throughout a micro-irrigation system. Takes
account of both variations in emitters and variations in the pressure under
which the emitters operate. (ASAE, 1998) (Emission uniformity is also used with
other types of irrigation systems. Editor)
emitter [] Small micro-irrigation
dispensing device designed to dissipate pressure and discharge a small uniform
flow or trickle of water at a constant discharge, which does not vary
significantly because of minor differences in pressure head. Also called a
"dripper" or "trickler". (ASAE, 1998)
- compensating emitter: See pressure compensating
emitter.
- continuous flushing emitter - Micro irrigation system
emitter designed to continuously permit passage of large solid particles
while operating at a trickle or drip flow, thus reducing filtration
requirements. (NRCS, 1997)
- flushing emitter- Emitter designed to have flushing flow of
water to clear the discharge opening every time the system is turned on.
(NRCS, 1997)
- line source emitter - Water is discharged from closely
spaced perforations, emitters, or a porous wall along the tubing. (NRCS,
1997)
- long-path emitter- Emitter which employs a long capillary
sized tube or channel to dissipate pressure. (NRCS, 1997)
- multi-outlet emitter- Device which supplies water to two or
more points through small diameter auxiliary tubing. (NRCS, 1997)
- non-pressure compensating emitter- Emitter designed
with a fixed orifice or other components and contains no pressure
compensating features.
- orifice emitter- Emitter which employs a series of orifices
to dissipate pressure. (NRCS, 1997)
- pressure compensating emitter - Emitter designed to
discharge water at a near constant rate over a wide range of lateral line
pressures. (NRCS, 1997)
- vortex emitter -Emitter which employs a vortex effect to
dissipate pressure. (NRCS, 1997)
entrance loss [] {ft, m Energy lost in eddies and
friction at the inlet to a conduit or structure. (ASAE, 1998)
evaporation*[E] {in./day, in./wk, mm/wk, mm/month} (part of ET)
- Water movement from a wet soil or plant surface which does not pass
through the plant. (Burt, 1998)
- Physical process by which a liquid is transformed to the gaseous state,
which in irrigation generally is restricted to the change of water from
liquid to vapor. Occurs from plant leaf surface, ground surface, water
surface and sprinkler spray. (NRCS, 1997)
evaporation pan []
- Standard U.S. Weather Bureau Class A pan (48-inch diameter by 10-inch
deep) used to estimate the reference crop evapotranspiration rate.
Water levels are measured daily in the pan to determine amount of
evaporation.
- Pan or container placed at or about crop canopy height containing water.
Water levels are measured daily in the pan to determine the amount of
evaporation. (NRCS, 1997)
evapotranspiration* [ET]
{in./day, in./week, mm/wk, mm/day } (11/6/99) Combination of water transpired
from vegetation and evaporated from the soil and plant surfaces. (ASAE, 1998)
- crop [ETc] (approved via RM)
- Crop evapotranspiration is the quantitative amount of ET within the
cropped area of a field, and which is associated with growing of a crop.
(Burt, et al. 1997) Same as plant water requirement.
Amount of water used by the crop in transpiration and building of plant
tissue, and that evaporated from adjacent soil or intercepted by plant
foliage. It is sometimes referred to as consumptive use.
(NRCS, 1997)
- potential [ETp, Etp, ](approved via
RM)
- Rate at which water, if available, would be removed from soil and plant
surfaces. (ASAE, 1998)
- Rate at which water, if available, would be removed from the soil and
plant surface expressed as the latent heat transfer per unit area or its
equivalent depth of water per unit area. (Jensen, 1980)
- reference [](approved via RM)
- [ETo] * Rate of evapotranspiration from an extensive surface
cool-season green grass cover of uniform height of 12 cm, actively growing,
completely shading the ground, and not short of water. (Mecham, Brent, 1999.
Unpublished; also see ASCE, 1990)
- [ETr]* Upper limit or maximum evapotranspiration that occurs
under given climate conditions with a field having a well-watered
agricultural crop with an aerodynamically rough surface, such as alfalfa
with 50 cm. of top growth. (Mecham, Brent, 1999. Unpublished; also see
ASCE, 1990)
exchange capacity: See
cation exchange capacity.
exchangeable sodium percentage* [ESP] {%}
- Fraction of cation exchange capacity of a soil occupied by sodium ions.
Exchangeable sodium, (meq/100 gram, spoil) divided by CEC (meq/100 gram
soil) times 100. It is unreliable in soil containing soluble sodium
silicate minerals or large amounts of sodium chloride. (NRCS, 1997)
- Percentage of the cation exchange capacity (meq.) of a soil which is
occupied by sodium. (Burt, 1998)
- Index of the saturation of the soil exchange complex with sodium ions. ...
(Hess, 1999)
D
fertigation [] Application of nutrients through an
irrigation system.
field capacity *[FC] {in./in., in./ft, %, bars, kPa, mm/m
} (approved via RM)
- Moisture remaining in a soil following wetting and natural drainage until
free drainage has practically ceased. (On-Farm Irrigation Committee, 1978)
- Amount of water remaining in a soil when the downward water flow due to
gravity becomes negligible. (ASAE, 1998)
final infiltration rate: See
basic intake rate.
fine sand [] Soil textural class. (Soil, 1996)
fine sandy loam [] Soil textural class. See also
soil texture. (Soil, 1996)
FIPT [] Acronym for female iron pipe thread. (Smith, 1997)
flood irrigation: See
irrigation systems.
flow rate* [Q or q] {gpm, gph, gal/min,
ft3/s, cfs, Litres/s, Litres/min, m3/h} (11/6/99) Rate of
flow or volume per unit period of time.
foot valve: See valve, foot.
free drainage [] Movement of water by gravitational
forces through and below the plant root zone. This water is unavailable
for plant use except while passing through the soil. (NRCS, 1997)
frequency distribution []
- Values in a sample are grouped into a limited number of classes. A
table is made showing the class boundaries and the frequencies (number of
members of the sample) in each class. The purpose is to show a compact
summary of the data. (Snedecor and Cochran, 1967)
- Measurement and presentation of various fractions of total water applied
for selected depth ranges referenced to average depth applied.
friable [] Soil consistency term referring to the ease
with which the soil aggregates may be crumbled (in the hand), i.e. a friable
soil is easily crumbled in the hand. (Hess, 1999)
friction factor, Christiansen* [F] {-} Friction factor or
coefficient used in the Christiansen Procedure to determine pressure loss in a
multiple outlet piping system.
friction factor (lateral) *[Ff] {psi/100 ft, m /100
m} Factor used to size pipe. (Head Layout, 1998.)
frost protection [] Applying irrigation water to affect
air temperature, humidity, and dew point to protect plant tissue from freezing.
The primary source of heat (called heat of fusion) occurs when water turns to
ice, thus protecting sensitive plant tissue. (NRCS, 1997)
full irrigation [] Management of water applications to
fully replace water used by plants over an entire field. (NRCS, 1997)
furrow irrigation: See
irrigation system, furrow.
friction factor , Christiansen
[F] {-} (approved via RM) Factor used to account for multiple outlets on a
lateral pipe when computing friction loss via the Christiansen Procedure.
(Reference Manual ch 2)
friction factor, Darcy Weisbach [f] {-} (approved via RM)
Friction factor used with Darcy Weisbach equation. (Reference Manual, ch 2)
friction loss [hf] {psi, ft, kPa, m}Also, referred
to as pressure loss.
- Amount of pressure lost through pipes due to water movement and
turbulence. (Carruthers, B. 2001, unpublished)
- Amount of pressure lost as water flows through an irrigation system (due
to friction against the pipe walls). (Rain Bird. 1997)
- As water moves through an irrigation system, pressure is lost because of
turbulence created by the moving water. This turbulence can be created
in pipes, valves or fittings. These losses are referred to as
friction losses. (Monroe, 1993)
fungicide [] Chemical pesticide that kills fungi or
prevents them from causing diseases on plants. (NRCS, 1997)
furrow []
- Small channel for conveying irrigation water down slope across the field.
Sometimes referred to as a rill or corrugation. (NRCS, 1997)
- Trench or channel in the soil made by a tillage tool.
furrow dike [] Small earth dike formed in a furrow
to prevent water translocation. Typically used with LEPA and LPIC systems.
Also used in non-irrigated fields to capture and infiltrate precipitation.
Sometimes called reservoir tillage. (NRCS, 1997)
furrow stream [] Stream flow in a furrow, corrugation or
rill. (NRCS, 1997)
G
gate, slide gate [] Device used to control the flow of
water to, from, or in a pipeline or open channel ... (NRCS, 1997)
gated pipe [] Portable pipe with small gates installed
along one side for distributing irrigation water to corrugations or furrows.
(ASAE, 1998)
gear drive sprinkler: See
sprinkler head.
gpm*[] {gpm, m3/s} Acronym for gallons per minute.
See flow rate.
gravitational water [] Soil water that moves into,
through, or out of the soil under the influence of gravity. (NRCS, 1997)
gravity (acceleration due to)* [g] {ft/s2,
m/s2} (11/6/99) Acceleration caused by the attraction of the mass of
earth to bodies at or near its surface. (i.e. 32.2 ft/sec2)
gray water [] Domestic wastewater other than that
containing human excreta such as sink drainage, washing machine discharge, or
bath water. (ASAE, 1998)
gross irrigation: See
irrigation, gross.
gross irrigation system capacity: See
system capacity, gross irrigation
gross water (irrigation) requirement: See
irrigation requirement, gross.
ground water [] Water occurring in the zone of saturation
in an aquifer or soil. (NRCS, 1997)
growing season [] {days} Period, often the frost-free period,
during which the climate is such that crops can be produced. (NRCS, 1997)
gypsum block [] Electrical resistance block in which the
material used to absorb water is gypsum. It is used to measure soil water
content in non-saline soils. (NRCS, 1997)
H
hard hose traveler: See
irrigation system: traveler.
head [H] {ft, m}
- atmospheric pressure *(head) [Ha] (11/6/99) Value
of atmospheric pressure at a specific location and condition.
- Head, dynamic [] {ft, m} Specific energy in a flow system.
(ASAE, 1998)
- head, discharge [Hd] Pressure head at the outlet
of the pump. (Pumps, 1998)
- head, elevation* [Hz, Z] (11/6/99) Head as
a result of elevation above a defined datum.
- head, friction *[Hf] (11/6/99) Energy head loss
caused by the friction of water flowing through a pipe.
- head loss *[HL] (11/6/99) Energy loss in
fluid flow. (ASAE, 1998)
- head loss, converging and diverging pipes [Hg]
{ft, m} (approved via RM) Energy loss associated with water flowing through
converging or diverging pipe sections. (Reference Manual, ch. 2)
- head loss, entrance [He] {ft. m} (approved via
RM) Energy loss associated with water flowing through the entrance of a
pipe. (Reference Manual, ch. 2)
- head loss, bends [Hb] {ft, m} (approved via
RM)Energy loss associated with water flowing through a bend in a pipe.
(Reference Manual, ch. 2)
- head, pressure * [Hpr] (11/6/99) Pressure energy
in a liquid system expresses as the equivalent height of a water column
above a given datum. (ASAE, 1998)
- head, static* [Hs] (11/6/99) Energy
associated with a static liquid system composed of elevation and pressure
components.
- head, static discharge* [] Static energy components
at the discharge of a pump including elevation and pressure.
- head, static suction* [] Vertical distance from the
pump centerline to the surface of the liquid when the liquid supply is above
the pump. (Pumps, 1998)
- head, total (dynamic )* [Ht, H,
TDH] (11/6/99)
- Head required to pump water from its source to the point of discharge.
Equal to the static lift plus friction head losses in pipes and fittings
plus velocity head. (NRCS, 1997)
- Energy in the liquid system expressed as the equivalent height of a
water column above a given datum. (ASAE, 1998)
- Sum of static, pressure, friction and velocity head that a pump works
against while pumping at a specific flow rate. (Reference Manual)
- head, total suction* [] Head required to lift water
from the water source to the centerline of the pump plus velocity head,
entrance losses and friction losses in suction pipeline. (ASAE, 1998)
- head, vapor pressure* [Hvp]
(11/6/99) Pressure head at which the liquid (water) will vaporize or boil at
a given temperature.
- head, velocity* [Hv] (11/6/99)
- Head or energy caused by the velocity of a moving fluid... (ASAE,
1998)
- Amount of pressure required to generate a specific velocity. This
is the amount of energy or pressure that is used to make the water move at a
given velocity. (Monroe, 1995)
head ditch [] Ditch across the upper end of a field used
for distributing water in surface irrigation. (ASAE, 1998)
head gate [] Water control structure at the entrance to a
conduit or canal. (ASAE, 1998)
head loss See head.
head spacing: See spacing between sprinklers.
head to head spacing [] Spacing of sprinkler heads
so that each sprinkler throws water to the adjacent sprinkler.
height (above a datum) [z] {ft, m} Linear dimension used
to describe the vertical distance from a point to a datum.
herbicide [] Chemical substance designed to kill or
inhibit the growth of plants, especially weeds. (NRCS, 1997)
high density polyethylene [HDPE] One of several forms of
polyethylene used to make pipe and other irrigation components.
horizon (soil) [] Layer of soil or soil material
approximately parallel to the land surface and differing from adjacent
genetically related layers in physical, chemical, and biological properties or
characteristics such as color, structure, texture, consistency, kinds and number
of organisms present, degree of acidity or alkalinity, etc. (Soil, 1996)
horsepower [] {hp, kw}
- water horsepower* [Whp, WHP] (11/6/99) Energy added
to water by a pump. (Reference Manual)
- input horsepower* [Ihp, IHP] Energy added to a
motor or engine
- brake horsepower * [Bhp, BHP] (11/6/99) Power required
to drive a pump. (Reference Manual)
- miscellaneous component energy losses [HPx] {hp}
(Reference Manual, ch. 4)
hose bib [] Valve configured to be mounted on a wall
having threads to accommodate the connection of a water hose.
hose drag traveler: See
irrigation system.
humid climate: See climate.
hydrant [] Outlet, usually portable, used for connecting
surface irrigation pipe to an alfalfa valve outlet. (NRCS, 1997)
hydraulic conductivity * [K] {in./h, mm/h}
- Coefficient describing the ease at which the soil pores permit water
movement. (NRCS, 1990)
- Soil-water characteristic describing the ability of water to flow through
a particular soil.
hydraulic valve: See valve.
hydrozone [] Grouping of plants with similar water
requirements so that they can be irrigated with a common zone. (Weinberg and
Roberts, 1988)
hygroscopic water []
- Water which is bound tightly by the soil solids at potential values lower
than -31 bars. (NRCS, 1990)
- Water that is tightly held by soil particles. It does not move with
the influence of capillary action or gravity, and it is normally unavailable
to plants. (Drip, 1999.)
I
ID *[] {in., mm} (11/6/99) Abbreviation for inside diameter
(usually of a pipe).
impact drive: See
sprinkler head.
impact drive sprinkler: See
sprinkler head.
impact power [] {watts, horsepower}
- Rate at which drops deliver kinetic energy to the soil. (Solomon, et al.
1996)
- Kinetic energy of impact on soil per unit volume. (Contractor pg 36, 1999)
impact rate [] {hp/ft2, kw/m2}
- Impact power per unit area. (Solomon, et al, 1996)
- Impact power per square foot. (Contractor pg 36, 1999)
infiltration [] See also
intake rate.
- Process of water movement through the soil surface into the soil matrix.
(Burt et al, 1997).
- The act of water entering the soil profile. (Rain Bird, 1997)
infiltration rate [I] {in./h, in.3/h/in.2,
mm/h} (Preferred term is intake rate.)
- Downward flow of water into the soil at the air-soil interface.
(NRCS, 1997)
- Volume of water infiltrating through a horizontal unit area of soil
surface at any instant. (Hess, 1999)
- How quickly water moves into the soil. (Monroe, 1993)
infiltrometer [] Device used to measure the infiltration rate /
intake rate of water into soil. (NRCS, 1997)
- ring infiltrometer [] Consists of metal rings that
are inserted (driven) into the soil surface and filled with water. The
rate at which water enters the soil is observed. (NRCS, 1997)
- sprinkler infiltrometer [] Consists of a sprinkler
head(s) that applies water to the soil surface at a range of rates of
less-than to greater than soil infiltration rates. Maximum
infiltration rates are observed and recorded. (NRCS, 1997)
- flowing infiltrometer [] Consists of an inlet device
to apply a specific flow rate to a furrow and a collection sump with a pump
to return tail water to the inlet device. Water infiltrated by the
soil in the test section (typically 10 meters) is replaced with water from a
reservoir to keep the flow rate constant. The rate of water
infiltrated verses time is also plotted. An equation (typically for a
curvilinear line) then represents the intake characteristics for that
particular soil condition. (NRCS, 1997)
initial intake: See intake.
input horsepower: See
horsepower.
inrush current [] {amps} Current necessary to initially open
the solenoid valve. (Smith, 1997)
instantaneous application rate: See
precipitation rate.
intake family [] Grouping of intake characteristics into
families based on field infiltrometer tests on many soils. (NRCS,
1997)
intake, initial [] {in./h, mm/h} Depth (rate) of water absorbed
by a soil during the period of rapid or comparatively rapid intake following
initial application. (NRCS, 1997)
intake rate (of soil) * [ I] {in./h, mm/h } Rate that
(irrigation) water enters the soil at the surface. (NRCS, 1997)
intake rate (basic)* [Ib]
{in./h, mm/h} Rate at which water percolates into the soil after infiltration
has decreased to a low and nearly constant value. (ASAE, 1998)
interception [] {in., mm} Part of precipitation or sprinkler
irrigation system applied water caught on the vegetation and prevented from
reaching the soil surface. (NRCS, 1997)
internal manual bleed [] Feature which allows an
automatic valve to be opened manually (without controller) by releasing water
from above the diaphragm to the downstream side of the valve. Useful
during installation, system start-up and maintenance operations when it is
undesirable for water to escape into the valve box. (Rain Bird, 1997)
inverted siphon [] Closed conduit (for conveying water)
with end sections above the middle section; used for crossing under a
depression, under a highway or other obstruction. Sometimes called a sag
pipe. (NRCS, 1997)
IPS: See iron pipe size.
iron pipe size* [IPS] {in., mm} One of several systems
which specify pipe dimensions.
irrecoverable water loss [] {in., mm} Water loss that becomes
unavailable for reuse through evaporation, phreatophytic transpiration, or
ground-water recharge that is not economically recoverable. (NRCS, 1997)
irrigable area [] {acres, ha} Area capable of being irrigated,
principally based on availability of water, suitable soils, and topography of
land. (NRCS, 1997)
irrigation []
- Intentional application of water to the soil, usually for the purpose of
crop production (reclaiming soils, temperature modification, improving crop
quality). (Soil, 1996)
- Intentional application of water for purposes of sustained plant growth
and/or optimized production. (Spofford, T. L., 1999. Unpublished)
irrigation audit [] Procedure to collect and present
information concerning the uniformity of application, precipitation rate, and
general condition of an irrigation system and its components. (Carruthers, B.
2001, unpublished)
irrigation consumptive use coefficient [ICUC] {-} See
coefficient.
irrigation design Plan of an irrigation system with pipe
sizing, head layout and valve location. (Masdon, S., Water
Management Committee, 2001)
irrigation district [] Cooperative, self-governing,
semipublic organization set up as a subdivision of a state or local government
to provide irrigation water. (NRCS, 1997)
irrigation efficiency: See
efficiency.
irrigation frequency* [] {-/week} Measure of the number of
irrigations per unit time.
irrigation
- gross [Igross] {in., mm} Water actually applied,
which may or may not be total irrigation water requirement; i.e. leaving
storage in the soil for anticipated rainfall, harvest. (NRCS, 1997)
- net [Inet] {in., mm} Actual amount of applied
irrigation water stored in the soil for plant use or moved through the soil
for leaching salts. Also includes water applied for crop quality and
temperature modification; i.e. frost control, cooling plant foliage and
fruit. Application losses, such as evaporation, runoff, and deep
percolation, are not included. (NRCS, 1997) See also,
irrigation requirement, net.
irrigation interval* [IN] {h, days} (approved via RM)
- Average time interval between the commencement of successive irrigations
for a given field (or area). (ASAE, 1998)
- Time between irrigation events. Usually considered the maximum
allowable time between irrigations during the peak ET period. (NRCS, 1997)
irrigation period*[] {h} Time that it takes to apply one
irrigation to a given design area during the peak consumptive-use period of the
crop being irrigated. (Soil, 1996)
irrigation (water) requirement
- net irrigation requirement* [IRnet, ]
{in., mm} (11/6/99)
- Depth of water, exclusive of effective precipitation, stored soil
moisture, or ground water, that is required for meeting crop
evapotranspiration for crop production and other related uses. Such
uses may include water required for leaching, frost protection, cooling and
chemigation. (NRCS, 1997)
- Difference between evapotranspiration and effective precipitation.
(Landscape, 1996).
- Quantity of water needed by the landscape to satisfy the evaporation,
transpiration and other uses of the water in the soil. (Rain Bird, 1997)
- gross irrigation requirement*[IRgross,
] {in., mm} (11/6/99)
- Total amount of water applied (or desired). See also
irrigation water requirement.
- Total irrigation requirement including net crop requirement plus any
losses incurred in distributing and applying and in operating the
system. (NRCS, 1997)
- irrigation water requirement [IWR] {in., mm}
- Calculated amount of water needed to replace soil water used by
the crop (soil water deficit), for leaching undesirable elements through and
below the plant root zone, plus other needs; after considerations are made
for effective precipitation. (NRCS, 1997)
- Plant water requirement adjusted for application uniformity (and
efficiency). (Contractor, 1999) (Same as gross irrigation requirement.)
irrigation sagacity [IS] {%} Ratio of volume of irrigation
water beneficially or reasonably used to the total volume of irrigation water
that has left the region, both in a specified period of time. (Burt et al, 1997)
irrigation schedule []
- Procedure of establishing and implementing the time and amount of
irrigation water to apply.
- Determining when to irrigate and how much water to apply, based upon
measurements or estimates of soil moisture or crop water used by a plant.
(NRCS, 1997)
- Set of specifications identifying times to turn on and off water to
various zones of an irrigation system.
irrigation scheduling: See
scheduling.
irrigation set [] {acres, ha} Area irrigated at one time within
a field. (Soil, 1996)
irrigation set time: See set
time.
irrigation slope [] {%, ft / 100 ft, m/100m} Elevation
difference along the direction of irrigation. Sometimes called irrigation grade.
(NRCS, 1997)
irrigation system []
- Physical components (pumps, pipelines, valves, nozzles, ditches, gates,
siphon tubes, turnout structures) and management used to apply irrigation
water by an irrigation method. (NRCS, 1997)
- All equipment required to convey water to or within the design area.
(ANSI/ASAE S376.2 JAN98)
- Set of components which includes (may include) the water source, water
distribution network, control components and possibly other general
irrigation equipment. (Rain Bird, 1997)
- drip/trickle/micro[]
- Micro irrigation system (low pressure and low volume) wherein
water is applied to the soil surface as drops or small streams through
emitters. Preferred term is drip irrigation. (NRCS, 1997)
- Method of micro-irrigation wherein water is applied to the soil surface
(or below the soil surface) as drops or small streams through emitters.
Discharge rates are generally less than 2 gph for single-outlet emitters and
3 gph per meter for line-source emitters. (ASAE, 1998)
- Method of micro irrigation wherein water is applied to the soil surface
as drops or small streams through emitters (preferred term is drip
irrigation). (ASAE, 1998)
- bubbler irrigation [] Application of water to flood
the soil surface using a small stream or fountain. The discharge rates
for point-source bubbler emitters are greater than for drip or subsurface
emitters but generally less than 1 gpm. A small basin is usually
required to contain or control the water. (ASAE, 1998)
- surface []
- Type of irrigation where water is distributed to the plant
material by a ground surface distribution network possibly including rows or
dikes.
- Broad class of irrigation methods in which water is distributed over the
soil surface by gravity flow. (ASAE, 1998)
- basin irrigation [] Irrigation by flooding areas of
level land surrounded by dikes. Used interchangeably with level border
irrigation, but usually refers to smaller areas. (ASAE, 1998)
- border irrigation [] Irrigation by flooding strips
of land, rectangular in shape and cross leveled, bordered by dikes.
Water is applied at a rate sufficient to move it down the strip in a uniform
sheet. Border strips having no down field slope are referred to as
level border systems. Border systems constructed on terraced lands are
commonly referred to as benched borders. (ASAE, 1998)
- cablegation [] Method of surface irrigation that
uses gated pipe to both transmit and distribute water to furrows or border
strips. A plug, moving at a controlled rate through the pipe, causes
irrigation to progress along the field and causes flow rates from any one
gate to decrease continuously from some maximum rate to zero. (ASAE, 1998)
- check irrigation [] Modification of a border strip
with small earth ridges or checks constructed at intervals to retain
water as the water flows down the strip. (ASAE, 1998)
- check basin irrigation [] Water is applied rapidly to
relatively level plots surrounded by levees. The basin is a small
check. (Soil, 1996)
- corrugation irrigation [] Method of surface
irrigation similar to furrow irrigation, in which small channels, called
corrugations, are used to guide water across a field. No attempt is
made to confine the water entirely to the corrugations. (ASAE, 1998)
- flood irrigation [] Method of irrigation where water
is applied to the soil surface without flow controls, such as furrows,
borders or corrugations. (ASAE, 1998)
- furrow irrigation [] Method of surface irrigation
where the water is supplied to small ditches or furrows for guiding across
the field. (ASAE, 1998)
- alternate set irrigation [] Method of
managing irrigation whereby, at every other irrigation, alternate
furrows are irrigated, or sprinklers are placed midway between their
locations during the previous irrigation. (ASAE, 1998)
- alternate side irrigation [] Practice of furrow
irrigating one side of a crop row (for row crops or orchards) and then,
at about half the irrigation time, irrigating the other side.
- cutback irrigation [] Reduction of the furrow or
border inflow stream after water has advanced partially or completely
through the field in order to reduce runoff. (ASAE, 1998)
- surge [] Surface irrigation technique wherein flow is
applied to furrows (or less commonly, borders) intermittently during a
single irrigation set. (ASAE, 1998)
- wild flooding[] Surface irrigation
system where water is applied to the soil surface without flow controls,
such as furrows, borders (including dikes), or corrugations. (NRCS, 1997)
- sprinkler [] Type of irrigation using
mechanical devices with nozzles (sprinklers) to distribute the water by
converting water pressure to a high velocity discharge stream or streams.
- continuous/self-move system []
- Lateral, sprinkler (traveler), or boom that is continuous or self
moving while water is being applied. Power for moving the facility
is typically provide by electric or hydraulic (water) motors or small
diesel engines. (NRCS, 1997)
- boom [] Elevated, cantilevered boom with
sprinklers mounted on a central stand. The sprinkler-nozzle
trajectory back pressure rotates the boom about a central pivot which is
towed across the field by a cable attached to a winch or tractor.
Can also be a periodic-move system. (NRCS, 1997)
- center pivot [] Automated irrigation system
consisting of a sprinkler lateral rotating about a pivot point and
supported by a number of self-propelled towers. Water is supplied
at the pivot point and flows outward through the pipeline supplying the
individual sprinklers or spray heads. (NRCS, 1997)
- corner pivot [] Additional span or other equipment
attached to the end of a center pivot irrigation system that allows the
overall radius to increase or decrease in relation to field boundaries.
(NRCS, 1997)
- lateral (linear) move [] Automated irrigation
machine consisting of a sprinkler line supported by a number of
self-propelled towers. The entire unit moves in a generally
straight path perpendicular to the lateral and irrigates a basically
rectangular area. (NRCS, 1997) (Soil, 1996)
- traveler (traveling gun) irrigation []
- Large rotating sprinkler(s) mounted on a trailer to deliver
water in a circle. The sprinkler and associated trailer are towed
through the field by any of several means. ... (NRCS, 1997)
- Travelers are also called cable-tow, hard hose and hose drag.
- periodic-move system [] System of laterals,
sprinklers heads (gun types), or booms that are moved between irrigation
settings. They remain stationary while applying water. (NRCS, 1997)
- gun type [] Single sprinkler head with large
diameter nozzles, supported on skids or wheels. Periodically moved
by hand or mechanically with a tractor, cable, or water supple hose. ...
(NRCS, 1997)
- portable (hand move) irrigation [] Sprinkler
system which is moved by uncoupling and picking up the pipes manually,
requiring no special tools. (Soil, 1996)
- side move [] Sprinkler system with the supply pipe
supported on carriages and towing small diameter trailing pipelines each
fitted with several sprinkler heads. (NRCS, 1997)
- side role (wheel line) [] Supply pipe is usually
mounted on wheels with the pipe as the axle and where the system is
moved across the field by rotating the pipeline by engine power. (NRCS,
1997)
- towed sprinkler [] System where lateral lines are
mounted on wheels, sleds, or skids and are pulled or towed in a
direction approximately parallel to the lateral. Rollers or wheels
are secured in the ground near the main water supply line to force an
offset in the tow path equal to half the distance the lateral would have
been moved by hand. (NRCS, 1997)
- solid set/fixed [] System of portable surface
or permanently buried laterals totally covering the irrigated area or field.
Typically several adjacent laterals or heads are operated at one time.
Portable laterals are typically removed from the field at end of
germination, plant establishment, or the irrigation season and are replaced
the next irrigation system. (NRCS, 1997)
irrigation water requirement: See
irrigation requirement. .
isolation vale: See valve.
J
jockey pump: See pump.
K
kinematic viscosity* [u] {ft2/s, m2/s}
Measure of the resistance of a liquid to shear forces.
L
lag time (flood irrigation) [] {h, min} Period between
the time that the irrigation stream is turned off at the upper end of an
irrigated area and the time that water disappears from the surface at the point
or points of application. (Soil, 1996)
landscape coefficient: See
coefficient.
lateral []
- Secondary or side channel, ditch or conduit. Also call "branch
drain" or "spur".
- Water delivery pipeline that supplies irrigation water from the main line
to sprinklers or emitters. (ASAE, 1998)
- The pipe installed downstream from the control valve on which the
(sprinkler heads or) emission devices are located. (Rain Bird, 1997)
lateral friction factor: See
friction factor.
lath box [] Wooden box that is placed in a ditch bank to
transfer water from an irrigation ditch to the field to be irrigated (preferred
term is spile). (ASAE, 1998)
leaching [] Removal of soluble material from soil or
other permeable material by the passage of water through it. (ASAE, 1998)
leaching fraction [LF] {-} Ratio of the depth of subsurface
drainage water (deep percolation) to the depth of infiltrated irrigation water
(see
leaching requirement). (ASAE, 1998)
leaching requirement [LR] {in., mm} Quantity of irrigation
water required for transporting salts through the soil profile to maintain a
favorable salt balance in the root zone for plant development. (ASAE, 1998)
length* [L, s] {ft, mm} Linear dimension used to describe the
quantity / amount / distance of pipe, conductor or similar material in various
equations.
length of run [] {ft, mm} Distance water must flow in furrows
or borders over the surface of a field from the head to the end of the field.
(ASAE, 1998)
LEPA [] Acronym for Low Energy Precision
Application.
limited irrigation [] Management of irrigation
applications to apply less than enough water to satisfy the soil water
deficiency in the entire root zone. Sometimes called " deficit" or "stress
irrigation". (ASAE, 1998)
line source [] Continuous source of water emitted along
a line. (ASAE, 1998)
line source emitter: See emitter.
Loam [] The textural class name of soil having a moderate
amount of sand, silt, and clay. Loam soils contain 7-27%clay, 28-50%silt, and
<52%sand. (Brady, 1990)
long path emitter: See emitter.
LPIC [] Acronym for Low Pressure In Canopy.
looped circuit [] Piping system, usually a main line,
that closes back on itself in a loop, thus providing water to any location from
two routes.
Low Energy Precision Application [LEPA] A water,
soil, and plant management regime where precision down-in-crop applications of
water are made on the soil surface at the point of use. Application devices are
located in the crop canopy on drop tubes mounted on low pressure center pivot
and linear move sprinkler irrigation systems. ... (NRCS, 1997)
Low Pressure In Canopy [LPIC] Low-pressure
in-canopy system that may or may not include a complete water, soil and plant
management regime as required in LEPA. Application devices are located in
the crop canopy with drop tubes mounted on low-pressure center pivot and linear
move sprinkler irrigation systems... .(NRCS, 1997)
low head drainage []
- Condition in which water drains partially or completely out of the lateral
line through the sprinkler head after each irrigation cycle is completed.
(Keesen, 1995)
lower quarter distribution uniformity: See
distribution uniformity.
lysimeter []
- Device for measuring deep percolation from a soil profile, usually
consisting of an enclosed volume of undisturbed soil with some means of
collecting drainage water. It may also include some method of
measuring changes in the volume of stored soil water. (Hess, 1999)
- Isolated block of soil, usually undisturbed and in situ, for measuring the
quantity, quality, or rate of water movement through or from the soil.
(NRCS, 1997)
- Device and monitoring system used to measure the evapotranspiration (ET)
rate using a container closed at the bottom and with the top flush with
surrounding grade and planted with turf. After rainfall and irrigation
application are accounted for, daily change in the weight of the lysimeter
is directly related to ET. (Smith, S.W., 1997)
M
main (mainline) []
- Water delivery pipelines that supply water from the control station to the
manifolds. (ASAE EP405.1 DEC99)
- Pipe usually under constant pressure which supplies water from the point
of connection to the control valves (or valve-in-head sprinklers). (Rain
Bird, 1997)
management allowable (allowed)
depletion (deficit) *[MAD] {%, -} (11/6/99)
- See similar term, maximum allowable deficiency.
- Desired soil moisture deficit at the time of irrigation. (On-Farm
Committee, 1979)
- Portion of available water that is scheduled to be used
prior to the next irrigation.
- Planned soil moisture deficit at the time of irrigation. (NRCS,
1997)
manipulated soils: See
disturbed soils.
manufacturer's
coefficient of variation* [Cv] {-}Measure of the
variability of discharge of a random sample of a given make, model, and size of
micro-irrigation emitter, as produced by the manufacturer and before any field
operation or aging has taken place; equal to the ratio of the standard deviation
of the discharge of the emitters to the mean discharge of the emitters. (ASAE,
1998)
manifold []
- Pipeline that supplies water to the laterals. (ASAE, 1998)
- Closely linked series of mainline piping supplying water to valves or
laterals. (Carruthers, B. 1999, Unpublished)
master valve: See valve.
matched precipitation rate [] System or zone in which all
the heads have similar precipitation rates is said to have matched precipitation
rates. (Monroe, 1993)
matric potential [] {ft, m} Dynamic soil property and will be
near zero for a saturated soil. Matric potential results from capillary
and adsorption forces. This potential was formerly called capillary
potential or capillary water. (NRCS, 1997)
maximum allowable deficiency* [MADp] {-}
- See Fig. 1 at end of document.
- See similar term,
management allowed depletion.
- Term used to estimate the amount of water that can be used without
adversely affecting the plant and is defined as the ratio of readily
available water to available water. (James, 1988).
maximum application rate [] {in./h, mm/h} Maximum discharge at
which sprinklers can apply water without causing significant translocation.
(NRCS, 1997)
median drop size [] {in., mm}
- Diameter where half the sprinkler's water volume falls in drops smaller,
and half falls in drops larger than the median size. (Solomon et al, 1996)
- Drop size where 50%of the water volume occurs in drops greater than this
size. (Contractor, 1999)
microclimate [] Atmospheric conditions within or near a
crop canopy. (NRCS, 1997)
microclimate factor: See
coefficient.
micro irrigation: See
irrigation system.
MIPT [] Acronym for male iron pipe thread. (Smith, 1997)
mist irrigation [] Method of micro-irrigation in which
water is applied in very small droplets. (ASAE, 1998)
mixed flow pump: See pump.
moisture deficit, soil moisture depletion. [] {in., mm}
Difference between actual soil moisture and soil moisture held in the soil at
field capacity. (NRCS, 1997)
moisture meter [] Device that monitors or
measures soil water content or tension. (Carruthers, B. 1999, unpublished)
moisture sensor []
- Instrument which monitors soil water content... (Rain Bird, 1997)
- Device that monitors or measures soil water content of tension.
(Carruthers, B, 1999, unpublished)
MPT [] {in., mm} Male nominal Pipe Threads. (Rain Bird, 1997)
multistage pump: See pump.
N
net irrigation: See irrigation,
net
net irrigation requirement [NIR] {in., mm} See
irrigation requirement, net.
net positive suction head *[NPSH] {ft, m} (11/6/99)
- Head that causes liquid to flow through the suction piping and enter the
eye of the pump impeller. (ASAE, 1998)
- net positive suction head available* [NPSHA] {ft, m}
(approved via RM) Pressure head that is supplied (is available)
to the eye of an impeller in a pump based on system characteristics.
(Reference Manual, ch. 4)
- net positive suction head required *[NPSHR] {ft, m}
(approved via RM) Minimum pressure head required at the eye of an impeller
in a pump to prevent cavitation. (Reference Manual, ch. 4)
net precipitation rate: See
precipitation rate
net (irrigation) water requirement [] {in., m} Same as
net irrigation requirement.
nominal [] {in., m} Named size which is usually not the
actual dimensions of the product. i.e. a half inch schedule 40 pipe is not
1/2 inch ID or OD.
nonbeneficial use: See use.
nonconsumptive use: See use.
nonpoint source pollution [] Pollution originating from
diffuse areas (land surface or atmosphere) having no well-defined source. (NRCS,
1997)
non-saline sodic soil [] Soil containing soluble salts
that provide an electrical conductivity of saturation extract (ECe) less than
4.0 mmhos/cm and an exchangeable sodium percentage (ESP) greater than 15.
Commonly called black alkali or slick spots. (NRCS, 1997)
nozzle [] Final orifice through which water passes from
the sprinkler or emitter to the atmosphere. (Rain Bird, 1997)
number of outlets *[No] {-} Term used to
describe the number of outlets in a lateral.
O
operating pressure [] {psi, kPa}
- Actual head pressure remaining at the sprinkler head after the total
pressure loss from the city main to the critical head is subtracted from the
starting static pressure. (Texas Natural Resource Conservation Commission)
- Pressure at which a system of sprinklers operates, usually measured at the
base or nozzle of a sprinkler. (Rain Bird, 1997)
opportunity time [] {min., h} Time that water inundates
the soil surface with opportunity to infiltrate. (NRCS, 1997)
orchard valve: See valve.
orifice []
- Opening with a closed perimeter through which water flows. Certain
shapes of orifices are calibrated for use in measuring flow rates. (ASAE,
1998)
- Opening in system component such as pipe, tubing, or nozzle. (Rain Bird,
1997)
Osmotic potential [] {ft, m} Potential attributable to the
presence of solutes in the soil- in other words, to the soil solution.
(Brady, 1990)
osmotic pressure (potential) See
potential.
[] {psi, ft, kPa, m}
oven dry []
- Drying of soil samples in an over for a sufficient period of time to reach
a constant weight. (Black, 1965)
- Refers to soil samples that have been dried in an oven at 105
C for 24 hours ... (Contractor, 1999)
overhead irrigation [] Same as
sprinkler irrigation.
overlap [] Area which is watered by two or more
sprinklers. (Rain Bird, 1997)
P
pan coefficient: See coefficient,
pan.
peak use rate [] {in./day, in./week} Maximum rate at which a
crop uses water. (NRCS, 1997)
percentage fines [] {%} Percentage of water volume falling in
fine (< 1 mm in diameter) drops. (Contractor, 1999) Term also used
relative to soil particle size.
percolation:
- beneficial deep percolation-leaching. [] {in.} is a beneficial use when it
leaches salts from the root zone to a level required for acceptable crop
production. (Burt et al 1997)
- nonbeneficial (excess) deep percolation [] {in.} If the actual depth of
deep percolation at a given location is more than the required beneficial
leaching depth, that which is in excess of the requirement is nonbeneficial.
(Burt et al 1997)
percolation rate [ ] {in./h, mm/h} Rate at which water moves
through porous media, such as soil. (ASAE, 1998)
performance curve [] Graph showing the capability of a
product with varying inputs. i.e. the dynamic head of a pump as it varies
with discharge.
permanent irrigation [] Irrigation having underground
piping with risers and sprinklers. (Soil, 1996) Preferred term is
stationary sprinklers.
(permanent) wilting point
* [PWP ] {%, in./in., in./ft , mm/m (approved via RM)
- Moisture content, on a dry weight basis, at which plants can no longer
obtain sufficient moisture from the soil to satisfy water requirements.
Plants will not fully recover when water is added to the crop root zone once
permanent wilting point has been experienced. Classically, 15
atmospheres (15 bars), soil moisture tension is used to estimate PWP. (NRCS,
1997)
- Moisture content of the soil after the plant can no longer extract
moisture at a sufficient rate for wilted leaves to recover overnight or when
placed in a saturated environment. (On-Farm Committee, 1978)
- Also known as wilting percentage, wilting coefficient or wilting point.
(Reference Manual)
permeability [] {in./h, mm/h}
- Qualitatively, the ease with which gases, liquids, or plant roots
penetrate or pass through a layer of soil. (NRCS, 1997)
- Quantitatively, the specific soil property designating the rate at which
gases and liquids can flow through the soil or porous media. (NRCS, 1997)
pesticide [] Chemical agent used to control specific
organisms. Includes insecticides, herbicides, and fungicides. (NRCS, 1997)
pipe dope [] Common name for commercial products used to
apply to pipe fittings to assist in the appropriate fit of the threaded joints.
pitot tube [] Small ell shaped tube which can be attached
to a pressure gage or other measuring device to measure the velocity head of
water discharging from a nozzle or flowing in a pipe.
pH* [] {-} Measure of acidity or alkalinity. (Burt,
1998)
plant available water
*[PAW] {in., mm} (11/6/99) Available water located in the root zone. Same
as
root zone available water. See Fig. 1
at end of document.
plant water requirement*
[PWR] {in./day, in/week, mm/day} Same as
evapotranspiration.
point of connection [POC] Location where irrigation
system is connected to a (potable) water supply.
polyethylene [PE] Flexible (usually black) plastic
material used to make irrigation pipe and other items.
polyvinyl-chloride [PVC]
Semi-rigid plastic material used to make irrigation pipe and other items.
porosity [] {%,-}
- Volume of pores in a soil sample relative to the total volume of the
sample. (Hess, 1999)
- Percentage of soil volume which is pore space. (Drip, 1997)
portable (hand move) irrigation: See
irrigation system.
positive displacement pump [] Pump that moves a fixed
quantity of fluid with each stroke or rotation, such as a piston or gear pump.
(ASAE, 1998)
potable water []
- Domestic or drinking water. It can be used as a source of irrigation
water, but once water enters an irrigation system (and passes through the
backflow device) it is no longer considered potable.
- Treated water which is meant for human consumption. It can be used for
irrigation systems as long as protection is provided to prevent
contamination of the domestic supply. (Texas Natural Resource Conservation
Commission)
potential
- soil water potential [] {ft, bar, kPa} Amount
of work that must be done per unit quantity of pure water in order to
transport reversibly and isothermally an infinitesimal quantity of water
from a pool of pure water at a specified elevation at atmospheric pressure
to the soil water at the point under consideration. (ASAE, 1998)
- total potential [Qt] {ft, bar, kPa} Sum of
matric, pressure, solute and gravitational potentials. (Burt, 1998)
- matric potential [Qm] {ft, bar, kPa} Attraction
of the solid soil matrix for water. (Burt, 1998)
- pressure potential [Qp] {ft, bar, kPa} Potential
caused by water pressure. (Burt, 1998)
- solute or osmotic potential [Qs] {ft, bar,kPa}
Potential caused by salinity. (Burt, 1998)
- gravitational potential [Qz] {ft, bar,
kPa} Relative height of a point above or below a reference elevation. (Burt,
1998)
potential evapotranspiration: See
evapotranspiration.
power *[P] {kw, hp} Rate of doing work. (Derryberry, 1994)
See also horsepower
precipitation [] {in., mm} Total of all atmospheric water
deposited on the surface. That is rain, snow, hail, dew and condensation.
(Hess, 1999)
precipitation rate* [PR]
{in./h, mm/h}(11/6/99)
- Rate at which a sprinkler system applies water to a given area.
(NRCS, 1997)
- precipitation rate, lowest [PRL] {in./h, mm/h}
Lowest precipitation rate in a defined contiguous area. (Landscape, 2000)
- instantaneous precipitation (application) rate [] {in./h,
mm/h} Maximum rate, usually localized, that a sprinkler application device
applies water to the soil. (NRCS, 1997)
- net precipitation rate * [PRnet] {in./h, mm/h}
Measure of the amount of water that actually reaches the landscape.
The net precipitation rate is the gross precipitation rate minus the losses
that occur between the sprinkler and the landscape surface.
(Landscape, 1996).
- sprinkler precipitation rate [] {in./h, mm/h} Precipitation
rate of a group of heads used together and all having the same arc, spacing
and flow. (Monroe, 1993)
- system precipitation rate [PR] {in./h, mm/h} Precipitation
rate for a system is the average precipitation rate of all sprinklers in a
given area regardless of the arc, spacing, or flow rate of each head.
(Monroe, 1993)
pressure* [P, p] {psi , lb/in.2,
kPa} (11/6/99) The force exerted over a surface divided by its area (Webster) In
irrigation, pressure usually describes the amount of energy available to move
water through a pipe, sprinkler or emitter.
pressure due to surge* [ps] {psi, kPa} Water
pressure caused due to changes in water velocity in a pipe system. Also
referred to as surge pressure.
pressure loss [] {psi, kPa, m} Amount of pressure lost as water
flows through a system. (Rain Bird, 1997)
pressure rating [PR] {psi, kPa, m} Estimated maximum internal
pressure that can be continuously exerted in a pipe or container with a high
degree of certainty that it will not fail. (ASAE, 1998; ANSI/ASAE S376.2 JAN98)
pressure regulator [] Device which maintains constant
downstream operating pressure (immediately downstream of the device) which is
lower than the upstream pressure. (Rain Bird, 1997)
pressure tank [] Enclosed container attached to a water
system usually containing an air pocket so that it behaves as a temporary water
supply.
pressure vacuum breaker: See
backflow prevention device.
profile (soil) [] Vertical section of the soil
through all its horizons and extending into the C horizon. (Soil, 1966)
profile (sprinkler) []
Chart showing the application rates vs. distance of throw for a sprinkler head.
(Center for Irrigation Technology. SpacePro Glossary). See also
single leg profile.
program: See
scheduling program.
project efficiency: See
efficiency.
propeller pump [] Pump which develops most of its head by
the lifting action of vanes on the water. (ASAE, 1998)
psi* [] {psi, kPa} Acronym for pounds per square inch.
See
pressure.
pump [] Mechanical device that
converts mechanical forms of energy into hydraulic energy. (Pumps, 1996)
- centrifugal[] Pump consisting of rotating vanes (impeller)
enclosed in a housing and used to impart energy to a fluid through
centrifugal force. (ASAE, 1998)
- jockey pump [] Usually a small pump used to
provide pressure and flow in a multi-pump system.
- mixed flow pump[] Centrifugal pump in which the
pressure is developed partly by centrifugal force and partly by the lifting
action of the impellers on the water. (ASAE, 1998)
- multi-stage [] Pump having more than one impeller
mounted on a single shaft. (NRCS, 1997)
- radial flow pump [ ] Centrifugal pump that uses
diffuser vanes to transform the velocity head into pressure head.
Commonly called a "turbine pump". (ASAE, 1998)
- submersible pump [] Pump where the motor and pump are
submersed below the water surface.
- trash pump [] Pump designed to pump large sized
particulate matter in addition to liquid.
- pto pump [] Pump driven by a separate power
supply connected to the pump by a power takeoff (pto) drive.
- vertical turbine [] Pump having one or more
stages, each consisting of an impeller on a vertical shaft, surrounded by
stationary and usually symmetrical guide vanes. Combines the
energy-imparting characteristics of axial-flow and propeller pumps. (ASAE,
1998)
pump column [] Pipe through which water from well pumps
(vertical turbine impellers) is conveyed to the ground surface (pump discharge
head). (ASAE, 1998)
pump efficiency: See efficiency.
pump start circuit [] Feature on automatic controllers
which supplies 24 VAC, which can be used to activate a pump through an external
pump start relay. (Rain Bird, 1997)
pump start relay [] Low-amperage or electric switch
designed for use with pump start circuits. (Rain Bird, 1997)
PVC: See
polyvinyl-chloride.
Q
quick coupling valve: See valve.
R
radial flow pump: See
pump.
radius of throw *[Rt] {ft, m} (11/6/99) Distance
from the sprinkler head to the furthest point of water application and is used
only for heads with circular wetting patterns. (Rochester, 1995)
rain gauge [] Device such as a graduated tube used
to measure the amount of rainfall.
rain sensor [] Device to measure rainfall.
rain shut-off device [] Device which prevents voltage
from the controller from activating the valves when a preset amount of rain
falls. (Rain Bird, 1997)
rain switch: See rain shut-off device.
rainfall intensity* [i] {in./h, mm/h} Rate of rainfall for the
design storm frequency and for the time of concentration of the drainage area.
(Used in rational method to compute runoff.) (LD, 1997)
rational equation [] Equation used to predict the
runoff from a watershed.
readily available water* [RAW] {in./ft, mm/m } (11/6/99)
Portion of available water that is more readily available for plant usage.
It varies with plant type. Also see related term maximum allowable
deficiency.
See Fig. 1 at end of document.
reasonable uses: See uses.
reclaimed water [] Water that has been
collected after an original use for reuse.
rectangular spacing: See
spacing.
reduced pressure (backflow preventer) device: See
backflow prevention device.
reference crop evapotranspiration. See
evapotranspiration.
relative humidity [] {%} Ratio of the amount of water vapor
present in the atmosphere to the amount required for saturation at the same dry
bulb temperature. (NRCS, 1997)
relay [] Electrical or electronic device
which uses a signal current to actuate a separate electrical circuit.
retraction [] Operation when the pop-up riser of a sprinkler
such as a spray head or rotor returns to the case in the ground. Also
called pop-down. (Rain Bird, 1997)
resistance *[R, Rw] {ohms} (11/6/99) Hindrance to
current flow in a given circuit (Reference Manual, ch. 5)
Reynolds Number *[R] {-} Dimensionless number used to
characterize flow of water.
riparian []
- Area of flowing streams that lies between the normal water line and some
defined high water line. (NRCS, 1997)
- Pertaining to the banks of a body of water; riparian owner is the one who
owns the banks. (NRCS, 1997)
- Riparian water right is the right to use and control water by virtue of
ownership of the banks. (NRCS, 1997)
riser [] Length of pipe which has male nominal pipe threads on
each end and is usually affixed to a lateral or sub-main to support a sprinkler
or anti-siphon valve. (Rain Bird, 1997)
R.P.A.: Abbreviation for reduced pressure assembly.
See backflow prevention devices,
reduced pressure.
root depth [] {in., ft, mm}
Preferred term root zone.
- effective [] {in., ft, mm} Depth from which roots extract
water. The effective rooting depth is generally the depth from which
the crop is currently capable of extracting soil water. However, it
may also be expressed as the depth from which the crop can extract water
when mature or the depth from which a future crop can extract soil water.
Maximum effective root depth depends on the rooting capability of the plant,
soil profile characteristics, and moisture levels in the soil profile.
(NRCS, 1997)
root zone* [RZ, d or drz,]
{in., ft, mm} (11/6/99)
- Depth of soil that plants roots readily penetrate and in which the
predominant root activity occurs. (ASAE, 1998)
- Area of the soil from which the crop roots extract water and nutrients.
(USDA, 1993)
- Crop rooting depth is typically taken as the soil depth containing 80
percent of plant roots. (NRCS, 1997)
- (May also be used as a portion of the root zone in equations where soil
characteristics change within the root zone.)
root zone available water [RZAW] {in., mm} See preferred term:
plant available water.
root zone depth: See root zone
and depth.
rotational speed *[N] {rpm} (approved via RM) Number of
revolutions made per unit time (usually minutes) by a shaft or other object.
rotor sprinkler: See
sprinkler head.
row spacing: See spacing, row
runoff [RO ] {in., mm}
- Portion of precipitation, snow melt or irrigation, that flows over the
soil, eventually making its way to surface water supplies. (ASAE, 1998)
- Surface water that leaves the subject region in liquid form. (Burt
et al, 1997)
runoff rate [] {in./h, mm/h}
- Rate at which water flows above ground from a watershed or field.
- Water which is not absorbed by the soil and drains to another location.
Runoff occurs when water is applied in excessive amounts or too quickly.
(Rain Bird, 1997)
run time *[RT] {minutes, h} (approved via RM) Length
of time to operate an irrigation system or an individual zone. (Reference Manual
, ch 6)
run time multiplier [RTM] {-} Multiplier used to
compensate for the lack of perfect uniformity in a sprinkler system.
(Scheduling, 1999). Also, see scheduling
coefficient.
S
sail index [] {ft2/gal, m2/m3}
- Cross-sectional area per unit volume of water of the drop comprising the
sprinkler spray. (Solomon, 1996)
- Cross sectional area of spray (drops) per unit volume of water.
(Contractor, 1999)
saline soil [] {-}
- Non-sodic soil containing soluble salts in such quantities that they
interfere with the growth of most crops ... (ASAE, 1998)
- Soil that has sufficient soluble salts to interfere with crop growth.
... (Hess, 1999)
- Non-sodic soil containing sufficient soluble salts to impair its
productivity for growing most crops. The electrical conductivity (ECe)
of the saturation extract is greater than 4 mmhos/cm, and exchangeable
sodium percentage (ESP) is less than 15; i.e., non-sodic. The
principal ions are chloride, sulfate, small amounts of bicarbonate, and
occasionally some nitrate. Sensitive plants are affected at half this
salinity, and highly tolerant ones at about twice this salinity. (NRCS,
1997)
saline-sodic soil [] Soil containing both sufficient
soluble salts and exchangeable sodium to interfere with the growth of most
crops. The exchangeable sodium percentage (ESP) is greater than or equal
to 15, and electrical conductivity of the saturation extract (ECe) is greater
than 4 mmhos/cm. It is difficult to leach because the clay colloids are
dispersed. (NRCS, 1997)
salinity [] Refers to the amount of salts dissolved in
soil water.
sand []
- Soil particles ranging from 50 to 200 :m (0.05 to 0.2 mm) in diameter.
- Soil material containing 85%or more in this size range. (ASAE, 1998)
saturation (of soil) [] {in./in., in./ft, %, mm/ m } Condition
where all soil pores / voids are filled with water. (NRCS, 1997)
schedule [] Method of specifying the dimensions and thus
the allowable operating pressure of pipe. For a specific schedule rating, the
wall thickness remains relatively constant for different pipe diameters,
resulting in lower allowable operating pressures for larger diameter pipe.
schedule, irrigation. See
irrigation schedule.
scheduling []
- Procedure of establishing and implementing the time and amount of
irrigation water to apply.
- Determining when to irrigate and how much water to apply, based upon
measurements or estimates of soil moisture or crop water used by a plant.
(NRCS, 1997)
scheduling coefficient*
[SC] {-}
- A number that relates to the uniformity of coverage and how to operate the
system to adequately irrigate the entire turf area. It indicates the
amount of extra watering time needed to adequately irrigate the driest
areas. (Solomon, 1988; Zoldoske et al, 1994)
- Numerical expression which serves as an index of the uniformity of water
application to a give area within a specific geometric arrangement of
sprinklers (e.g. triangular or square). Used to measure the uniformity
of landscape irrigation systems. (Rain Bird, 1997)
scheduling program []
Set of specifications identifying times to turn on and off water to various
zones of an irrigation system.
SDR: See standard
dimension ratio.
semiarid climate: See climate.
service factor [] {-}
service line [] Section of piping connecting larger
municipal supply line with water meter. (Carruthers, B., unpublished)
set time [] {h, min.}
- Elapsed time between the beginning and end of water application to an
irrigation set. (ASAE, 1998)
- Amount of time required to apply a specific amount of water during one
irrigation to a given area, typically refilling the plant root zone to field
capacity minus expected rainfall. (NRCS, 1997)
shutoff head [] {ft, kPa, m} Pressure head on the outlet side
of a pump at which the discharge drops to zero. Maximum pressure a pump
will develop at a given speed. (ASAE, 1998)
single leg profile []
Precipitation rate profile of an individual sprinkler head operating at a known,
constant pressure. (Oliphant, 1989)
siphon [] Closed conduit used to convey water across
localized minor elevation raises in grade. It generally has end sections
below the middle section. A vacuum pump is commonly used to remove air and
keep the siphon primed. The upstream end must be under the water surface.
Both ends must be under water, or the lower end must be closed to prime the
siphon. (NRCS, 1997)
siphon tube [] Relative short, light-weight, curved tube
used to convey water over ditch banks to irrigate furrows or borders. (ASAE,
1998)
silt [] Mineral portion of soil have particle sizes
ranging from 0.05 to 0.002 mm in diameter. Buckman and Brady, 1961
slide gate [] Head control valve, which slides on rails,
used to control drainage or irrigation water. (ASAE, 1998)
slip configuration or slip joint [] Connection
without threads (of PVC pipe or fittings) which is solvent welded. (Rain Bird,
1997)
sodic soil [] Non-saline soil containing sufficient
exchangeable sodium to adversely affect crop production and soil structure. ...
(ASAE, 1998)
sodium adsorption ratio *[SAR] {-}Portion of soluble sodium
ions in relation to the soluble calcium and magnesium ions in the soil water
extract ... (ASAE, 1998)
sodium adsorption ratio, adjusted [] {-} Sodium adsorption
ratio of a water adjusted for the precipitation or dissolution of CA2+
and Mg2+ that is expected to occur where a water reacts with alkaline
earth carbonates with a soil. ... (NRCS, 1997)
sodium percentage [] {%} Percentage of total cations that is
sodium in water or soil solution. (ASAE, 1998)
soil [] Unconsolidated minerals and material on the
immediate surface of the earth that serves as a natural medium for the growth of
plants. (ASAE, 1998)
soil horizon []
- Layer of soil differing from adjacent genetically related layers in
physical, chemical, and biological properties or characteristics. (ASAE,
1998)
- Layer of soil, usually approximately parallel to the soil surface, with
distinct characteristics produced by soil forming processes. (Hess, 1999)
soil moisture (water) depletion (deficit) *[SMD] {in., mm}
- Difference between field capacity and the actual soil moisture in the root
zone soil at any given time. It is the amount of water required to
bring the soil in the root zone to field capacity. (On-Farm Committee,
1979)
- Amount of water required to fill the plant root zone to field capacity.
(Burt, 1998)
soil profile []
- Vertical section of the soil from the surface through all its horizons
into the parent material. (ASAE, 1998)
- A vertical cross section through a soil which shows any layers or horizons
of which the soil is composed. (Hess, 1999)
soil reservoir capacity [SRC] {in., mm} Preferred term
plant available water.
soil series [] Lowest category of U.S. system of soil
taxonomy. A conceptualized class of soil bodies having similar
characteristics and arrangement in the soil profile. (ASAE, 1998)
soil structure: See structure.
soil texture: See texture.
soil water (moisture) [] {in., mm} All water stored in the
soil. (ASAE, 1998)
soil water characteristic curve [] Soil-specific relationship
between the soil-water matric potential and soil-water content. (ASAE, 1998)
soil water content* [WC%, θ]
{%, in./ft, in./in., mm/m} (11/6/99) Amount of water in a given volume (or
weight) of soil. ... (NRCS, 1997)
- Amount of water in a soil sample based on dry weight of the soil sample.
(Reference Manual)
soil-water (moisture) deficit or depletion [SWD] {in., mm}
- Depth of water required to bring a specific depth of soil to field
capacity at a particular time. (ASAE, 1998)
- Preferred term soil moisture
depletion.
soil-water potential: See potential.
soil-water tension [] {bars, atm., kPa} Measure of the
tenacity with which water is retained in the soil. It is the force per
unit area that must be exerted to remove water from the soil. ... (NRCS,
1997)
solenoid [] Electromagnet which is connected to a
controller and facilitates the opening and closing of automatic control valves
(or valve-in-head sprinklers). (Rain Bird, 1997)
solid set irrigation system: See
irrigation system.
spacing [] {ft, m}
- between sprinklers [Ss, S] (11/6/99) Distance
from one sprinkler to the next one along a row.
- between rows (of sprinklers) [Sr] (11/6/99)
Distance between adjacent rows of sprinklers.
- between drains [Sd] Distance between
parallel subsurface drain lines.
- equilateral triangular spacing [S] Sprinklers are
spaced in an equilateral triangular pattern.
- rectangular spacing [] Sprinklers are spaced in
a rectangular pattern.
- row spacing [] Distance between the rows of
sprinklers. (Monroe, 1993) See spacing between rows.
- head to head spacing [S] Sprinklers are spaced so that
each head throws water to the adjacent heads.
- triangular spacing [S] Sprinklers are spaced in
a triangular pattern.
species factor: See
coefficient.
specific gravity *[SP. GR. ] {-} Ratio of a substance's density
(or specific weight) to that of some standard substance such as water.
For liquids, the standard is water at sea level and 60
F (SP. GR. = 1).
specific speed *[Ns] {rpm} Index of pump type
related to impeller speed, discharge and total head. (ASAE, 1998)
specific volume [νs] {ft3/lb, m3/kg}
volume occupied by a unit mass of fluid. (Reference Manual).
specific weight* [(, or SW] {lb/ft3, kg/m3}
Weight per unit volume of a substance.
spile [] Conduit, made of lath, pipe or hose, placed
through ditch banks to transfer water from an irrigation ditch to a field.
(ASAE, 1998)
spray head: See sprinkler
head.
spray irrigation []
- Application of water by a small spray or mist to the soil surface, where
travel through the air becomes instrumental in the distribution of water.
(ASAE, 1998)
- (In some countries other than the US, sprinkler irrigation is called spray
irrigation.)
sprinkler distribution pattern []
- Water depth-distance relationship measured from a single sprinkler head.
(NRCS, 1997)
- Two dimensional water depth-distance relationship measured from a single
(or multiple) sprinkler head(s).
sprinkler (head) []
- Device for distributing water under pressure. (ASAE, 1998)
- Nozzle or device, which may or may not rotate, for distributing water
under pressure through the air. (NRCS, 1997)
- Hydraulically operated mechanical device which discharges water through a
nozzle or nozzles. (Rain Bird, 1997)
- gear drive sprinkler [] Sprinkler containing gears as
part of its rotational drive mechanism.
- impact drive [] Sprinkler which rotates using a
weighted or spring-loaded arm which is propelled by the water stream and
hits the sprinkler body, causing movement. (Rain Bird, 1997)
- rotor [] Sprinkler that rotates, but may more
specifically refer to a gear driven sprinkler.
- spray head [] Sprinkler head that does not rotate.
- valve-in-head [] Sprinkler head having an integrally
mounted valve.
sprinkler irrigation []
Method of irrigation in which the water is sprayed, or sprinkled, through the
air to the ground surface. (ASAE, 1998)
sprinkler irrigation system: See
irrigation system.
sprinkler precipitation rate: See
precipitation rate.
sprinkler profile: See
profile (sprinkler)
standard deviation* [SD] {same as units of variable}
Statistical term used to describe the distribution of values.
standard dimension ratio
*[SDR] {-} (approved via RM) Dimension Ratio is defined as the ratio of the
diameter of a pipe to its wall thickness. Outside diameter is used for OD rated
pipe while ID is used for ID rated pipe. Certain dimension ratios have been
selected by convention and standards to be used for construction of pipe. These
dimension ratios are referred to as standard dimension ratios. (ASAE, 1985)
static discharge head: See head.
static head: See head.
static lift [] {ft, m} Vertical
distance between water source and discharge water levels in a pump installation.
(ASAE, 1998) Same as total static head.
static pressure [] {psi, kPa, m}
- Pressure in a closed system, without any water movement. (Rain Bird, 1997
- Water pressure when the water is at rest. (Monroe, 1993)
- See also head.
static suction head: See head.
static suction lift: See
suction lift.
station [] Circuit on a controller which has the ability
to be programmed with a run time unique and separate from other circuits and
provides power to one or more remote control valves (or valve-in-head
sprinklers). (Rain Bird, 1997)
stationary sprinklers[] Irrigation having
underground piping with risers and sprinklers.
stress irrigation []
- Management of irrigation water to apply less than enough water to satisfy
the soil water deficiency in the entire root zone (ASAE, 1998)
- Preferred term is limited irrigation or deficit
irrigation. (ASAE, 1998)
structure (soil) []
- Combination or arrangement of primary soil particles into secondary units
or peds. The secondary units are characterized on the basis of size,
shape, and grade (degree of distinctness). (Soil, 1996)
- Combination of various soil particle types into a uniform mixture that
behaves as a single unit. Structural classes include granular, blocky,
and columnar massive, platy, prismatic, among others. (Monroe, 1993)
- Aggregation of primary soil particles, into units which are separated from
each other by surfaces of weakness. An individual natural soil
aggregate is called a ped in contrast to a clod caused by disturbance, or a
concretion caused by cementation. (Hess, 1999)
sub-humid climate: See climate.
sub-irrigation []
- Application of irrigation water below the ground surface by raising the
water table to within or near the root zone. (ASAE, 1998)
- Applying irrigation water below the ground surface either by raising the
water table or by using a buried perforated or porous pipe system that
discharges water directly into the plant root zone. ... (NRCS, 1997)
submersible pump: See pump.
subsurface drip irrigation [] Application of water below
the soil surface through emitters, with discharge rates generally in the same
range as drip irrigation. The method of water application is different
from and not to be confused with sub-irrigation where the root zone is irrigated
by water table control. (ASAE, 1998)
suction (static) lift [] {ft, m}
Vertical distance between the elevation of the surface of the water source and
the center of the pump impeller. (ASAE, 1998)
surface irrigation: See
irrigation systems.
surge irrigation: See
irrigation systems.
surge pressure.* [ps] {psi, kPa} Water
pressure caused by changes in water velocity in a pipe system.
swing check (valve): See valve.
swing joint [] Threaded connection of pipe and fittings
between the pipe and sprinkler which allows movement to be taken up in the
threads rather than as a sheer force on the pipe. Also used to raise or
lower sprinklers to a final grade without plumbing changes. (Rain Bird, 1997)
system capacity, [] {gpm/ac ? or
gpm, m3/ha} Ability of an irrigation system to deliver the net
required rate and volume of water necessary to meet crop water needs plus any
losses during the application process. Crop water needs can include soil
moisture storage for later plant use, leaching of toxic elements from the soil,
air temperature modification, crop quality, and other plant needs. (NRCS, 1997)
system precipitation rate: See
precipitation rate.
T
tail water
- Water in a stream or canal, immediately downstream from a structure.
- Excess irrigation water which reaches the lower end of a field. (ASAE,
1998)
tensiometer [] Instrument, consisting of a porous
cup filled with water and connected to a manometer or vacuum gauge, used for
measuring the soil-water matric potential. (ASAE, 1998)
textural class []
- Classification used to convey an idea of the textural makeup of soils and
to give an indication of their physical properties. Three broad groups of
these classes are recognized - sands, loams, and clays. Within each
group specified textural class names have been devised (i.e. loamy sand).
(Brady, 1990)
- Classification name given a soil because of the particular size groups of
particles found in the "A" horizon. (Contractor, 1999)
texture (soil) []
- Relative proportions of sand, silt and clay in a given soil. (Monroe,
1993)
- Relative proportions of the various soil separates in a soil as described
by the classes of soil texture... (Soil, 1996)
thrust block [] Normally, concrete poured in place at
changes in direction of water flow in piping systems (tees, ells ... ) to
prevent movement of the pipe. (Sneed, R. 1999. Unpublished)
tilth [] Physical condition of the soil in relation to plant
growth. (Brady, 1990; Drip, 1997)
time *[t] {s, min, h, day, fraction} (11/6/99) Term used
to describe the duration of an operation, e.g. an irrigation event.
total dissolved solids [TDS] {ppm, mg/L} Total dissolved
mineral constituents of water. (NRCS, 1997)
total dynamic head: See head.
total static head: See
static lift.
total suction head: See head.
total water holding capacity [TWHC] {in., mm} Preferred
term is Plant Available Water.
trajectory [] {degrees} Angle above horizontal of the stream of
water as it leaves the sprinkler head. (Rochester, 1995)
translocation [] Movement of water to other areas than
where it was applied. (NRCS, 1997)
transpiration* [T] {in./day, mm/day}
- Process of plant water uptake and use, beginning with absorption through
the roots and ending with transpiration at the leaf surfaces. See also
evapotranspiration. (NRCS, 1997)
- Liquid movement of water from the soil, into the roots, up the plant
stems, and finally out of the plant leaves into the air as vapor. (Burt,
1998)
traveler (traveling gun) irrigation: See
irrigation system.
triangular spacing: See
spacing.
trickle irrigation: See
irrigation system.
turbine pump: See pump, vertical
turbine.
turbulent flow [] Flow in which the fluid particles move
in an irregular random manner, in which the head loss is approximately
proportional to the second power of velocity. (ASAE, 1998)
turgid [] State of a plant cell when the cell wall is
rigid due to the hydrostatic pressure of liquid in the cell. (Hess, 1999)
U
unavailable soil water [] {in./ft, mm/m } Portion of
water in a soil held so tightly by adhesion and other soil forces that it cannot
be absorbed by plants rapidly enough to sustain growth. ... (ASAE, 1998)
uniformity []
- Term describing how evenly water is applied by overlapping sprinklers.
(Smith, 1997)
- Evenness of precipitation over a given area. (Contractor, 1999)
uniformity coefficient
- irrigation [] {-,%} Characteristic of the areal distribution
of water in a field as the result of an irrigation.
- soil [] {-} Ratio of the D60 size particles passing a screen
to the D10 size of a granular material. (ASAE, 1998)
uniformity coefficient (Christiansen's)*
[CU, CCU] {fraction, %} Measure of the uniformity of irrigation water
application. The average depth of irrigation water infiltrated minus the
average absolute deviation from this depth, all divided by the average depth
infiltrated. (ASAE, 1998)
union Pipe fitting used to connect two lengths of pipe in such
a way that neither has to be rotated .
unreasonable uses: See uses.
unsaturated zone [] Part of the soil profile in which the
voids (pore spaces) are not completely filled with water. (ASAE, 1998)
usable precipitation: See
effective precipitation.
uses*
- consumptive [] Total amount of water taken up by
vegetation for transpiration or building of plant tissue, plus the
unavoidable evaporation of soil moisture, snow, and intercepted
precipitation associated with vegetal growth. (ASAE, 1998)
- nonconsumptive [] Water that leaves the selected
region and not considered consumptive. Examples are runoff, deep
percolation, and canal spills. (Burt et al, 1997)
- beneficial [BU] Beneficial use of water supports the
production of crops: food, fiber, oil, landscape, turf, ornamentals, or
forage. ... (Burt et. al 1997)
- nonbeneficial [] Water utilized in plant growth which can
not be attributed as beneficial.
- reasonable [] In the context of irrigation
performance, all beneficial uses are considered to be reasonable uses.
Non-beneficial uses are considered to be reasonable if they are justified
under the particular conditions at a particular time and place. (Burt et at,
1997)
- unreasonable [] Unreasonable uses are non-beneficial uses
that, furthermore, are not reasonable; that is, they are without economic,
practical, or other justification. (Burt et al, 1997)
V
valve [] Device to control flow.
Valves used in pressurized systems include:
- alfalfa- Outlet valve attached to the top of a short
vertical pipe (riser) with an opening equal in diameter to the inside
diameter of the riser pipe and an adjustable lid or cover to control water
flow. A ring around the outside of the valve frame provides a seat and
seal for a portable hydrant. Typically used in border or basin
irrigation. (ANSI/ASAE S261.7 OCT96; NRCS, 1997)
- angle- Valve configured with its outlet oriented 90 degrees
from its inlet.
- air vent (air relief, air release)- Device that releases air
from a pipeline automatically without permitting loss of water. (NRCS, 1997)
- air vacuum, air relief- Device that releases air from a
pipeline automatically without permitting loss of water or admits air
automatically if the internal pressure becomes less than atmospheric. (NRCS,
1997)
- back flow prevention- Check valve that allows flow in
one direction. ... (NRCS, 1997) See specific valve for
details.
- ball-
- Valve in a pipeline used to start or stop flow by rotating a sealed ball
with a transverse hole approximately equal to the diameter of the pipeline.
Ball rotation is typically 90 degrees for a single-port control ...
(NRCS, 1997)
- Valve with an internally mounted ball with a hole in the center for
water to pass through. (Rotation of the ball one-fourth turn opens and
closes the valve.) (Rochester, 1995)
- butterfly- Valve in a pipeline to start or stop flow
by rotating a disk 90 degrees. The disk is about the same diameter as
the pipeline. ... (NRCS, 1997)
- check - Valve used in a pipeline which allows flow in
only one direction. (NRCS, 1997)
- chemigation- Valve especially designed to be used with the
injection of chemicals in an irrigation system.
- corporation stop- Quarter turn valve similar to a ball valve
with two exceptions. Internally there is a circular disk rather than a ball,
and there is no attached handle. (Rochester, 1995)
- curb stop- Physically the same as corporation valve but used
at a different location.
- drain valve
- automatic- Spring loaded valve that automatically opens
and drains the line when the pressure drops to near zero. (NRCS, 1997)
- flushing- Valve on the end of a line to flush out dirt and
debris. May be incorporated into an end plug or cap. (NRCS, 1997)
- float valve- Valve, actuated by a float, that automatically
controls the flow of water. (NRCS, 1997)
- foot valve- Check valve used on the bottom of the suction
pipe to retain the water in the pump when it is not in operation. (NRCS,
1997)
- flow control- Valve with automatically adjusts to provide a
predetermined downstream flow.
- gate- Valve in a pipeline used to start or stop water flow.
May be operated by hand with or with mechanical assistance or by high or low
voltage (solenoid) electric controlled mechanical assistance. Gate
valves consist of seated slide or gates operated perpendicular to the flow
of water. Head loss through a gate valve is typically less than a
globe valve, but more than a ball or butterfly valve. (NRCS, 1997)
- globe- Valve in a pipeline used to start or stop water flow.
Globe valves stop flow by positioning a disk and gasket over a machined seat
about the same diameter as the pipe. Globe valves are limited to
smaller sizes because of the high velocities and very high head loss through
the valve. (NRCS, 1997)
- hydraulic- Irrigation zone valve which uses small flexible
tubes and water under pressure to provide the actuation signal from the
controller to the valve.
- isolation- Any mechanical valve used to isolate a section of
a piping system.
- master- Valve used to protect the landscape from flooding in
case of a ruptured main or malfunctioning downstream valve. The master
valve is installed on the mainline after the backflow preventer (in some
systems). (Rain Bird, 1997)
- orchard- Outlet valve installed inside a short vertical pipe
(riser) with an adjustable cover or lid for flow control. Similar to
an alfalfa valve, but with lower flow capacity. Typically used in
basin irrigation. (ASAE, 1998)
- pilot- Small valve used to actuate a larger one.
- pressure regulating- Valve designed to automatically provide
a preset downstream pressure in a hydraulic system.
- pressure relief- Spring loaded valve set to open at a
pressure slightly above the operating pressure, used to relieve excessive
pressure and surges.(NRCS, 1997)
- pressure sustaining- Valve designed to provide a minimum
preset upstream pressure.
- quick coupling- Permanently installed valve which allows
direct access to the irrigation mainline. A quick coupling key is used to
open the valve. (Rain Bird, 1997)
- remote control- Valve which is actuated by an automatic
controller by electric or hydraulic means. Synonymous with
Automatic Control Valve. (Rain Bird, 1997)
- surge- Device in a pipe T fitting to provide flow in
alternate directions at timed intervals. Used in surge irrigation.
(NRCS, 1997)
- swing check- See check.
- vacuum relief valve- Valve used to prevent a vacuum in
pipelines and avoid collapsing of thin-wall pipe. (ASAE, 1998)
valve-in-head sprinkler: See
sprinkler head.
vapor pressure (head): See head.
velocity *[V,v] {ft/s, fps, m/s} (11/6/99)
- Usually refers to the average velocity computed as flow rate per
unit area of a pipe.
- Is the speed at which water moves through the system (pipe). (Monroe,
1993)
velocity head: See head.
vertical turbine pump: See pump.
voids ratio [] {-} Ratio of the volume of voids (pores) to the
volume of soil. (Hess, 1999)
voltage* [V] {volt} (11/6/99)
- Force required to push and pull a stream of electrons through a circuit.
(Derryberry, 1994)
- Amount of electrical potential required to force one amp of current flow
in a circuit against one ohm of resistance. (Reference Manual, ch. 5)
volute [] Refers to the flow path of water and its associated
pump casing as it leaves the impeller of a pump.
W
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]
Z
zone [] Section of an irrigation system served by a
single control valve. Zones are comprised of similar sprinkler types and
plant material types with similar water requirements and types. (Rain Bird,
1997)
Figure 1. Soil Water Terminology
![](images/glossary_fig1.gif)
soil moisture depletion
[SMD] {in., mm} The actual depletion of water at a particular time that reflects
the amount of water to fill the plant root zone to field capacity.
Notes on Metric Terminology
The commonly used terms in relation to water use for irrigation
are listed below litre (L) - the basic measure of liquid in small
quantities (pre-metric equivalent is the imperial gallon which is equal to 4.55
litres, not to be confused with the US gallon which is equivalent to only 3.78
liters).
In Australia, sprinkler flows are usually referred to as
Litres/minute (L/min) and pump flows are referred to as Liters/second (L/sec) or
m /hour.
cubic meter (m )
- the measurement unit for soil or excavation and also for water in medium-sized
quantities (pre-metric equivalent is the cubic yard or 'yard', which is
equivalent to 0.765 m .
The cubic foot was sometimes used for water measurement, and this is equivalent
to 0.028 m ).
megalitre (ML) - the measurement unit for large volumes of water
particularly in large reservoirs and in water allocations for irrigation (the
pre-metric equivalent is the acre foot which is equivalent to 1.23 megalitres).
Occasionally the megalitre is referred to as 'thousand cubic meters'or '000 m .
The megalitre is also the unit on which water charges are based in irrigation
areas and projects.
NOTE: One ML applied to one ha of land is equivalent to an application
depth
of 100 mm (or about 4 inches).
millimeter (mm) - this is the measurement unit for depth of rainfall
or depth of irrigation applied. It is also used for dimensioning and pipe
sizing references. The inch is equivalent to 25.4 mm.
cumec (m /s)
- the term 'cubic meters per second'is used to measure very large water flow
rates in rivers or channels (pre-metric equivalent is the 'cusec'or cubic feet
per second which is equivalent to 0.0283 cumec: for smaller flow rates liters
per second is used in place of cusecs or gallons per hour).
kilopascal (kPa) - the unit of pressure. To convert pounds per square
inch (p.s.i.) to kilopascals, multiplying by 7 gives an approximate conversion
to about 2%accuracy. In irrigation practice, pressure is often expressed as
'metres head'that can be converted to kPa by multiplying by 9.8.
kilowatt (kW) - the unit of power for electric motors and internal
combustion engines. The pre-metric equivalent is the 'horsepower'which is a
smaller unit, about 3/4 of the power of the kilowatt.
Area - For an approximate conversion of acres to hectares multiply by
0.4.
References
Agriculture, 1997. Agriculture: A Glossary of Terms,
Programs, Laws. Committee for the National Institute for the
Environment. Congressional Research Service. Report to Congress.
Washington, DC
ANSI/ASAE S376.2 JAN 98. Design, Installation and Performance of
Underground,
Thermoplastic Irrigation Pipelines. ASAE Standards 2000.
American Society of Agricultural Engineers. St. Joseph, MI.
ANSI/ASAE S261.7 Oct96 Design and Installation of Nonreinforced
Concrete Irrigation Pipe Systems. ASAE Standards 2000. American Society of
Agricultural Engineers. St. Joseph, MI.
ASAE, 1985. Design, Installation and Performance of Underground
Thermoplastic Irrigation Pipelines. ASAE Standard S376.1.
ASAE, 1998. Soil and Water Terminology. ASAE S526.1
MAR95. ASAE St. Joseph, MI 49085-9659 USA
ASCE, 1990. ASCE Manual and Reports on
Engineering Practice 70. American Society of Civil Engineering.
ASAE/ EP405.1 DEC99. Design and Installation of Microirrigation
Systems. ASAE Standards 2000. American Society of Agricultural Engineers. St.
Joseph, MI.
Black, C.A. 1965. Methods of Soil Analysis, Part 1.
Number 9, Agronomy. American Society of Agronomy. Madison, Wisconsin.
Brady, N.C. 1990. The Nature and Properties of Soils.
MacMillan Publishing Company. New York.
Buckman, H.O. and N.C. Brady. 1961 The Nature and Properties
of Soils. The Macmillan Co., New York.
Burt, C.M. 1998. Ag-Irrigation Management. 1998.
Irrigation Training and Research Center. California Polytechnic State
University. San Luis Obispo, CA
Burt, C.M., A.J. Clemmons, T.S. Strelkoff, K.H. Solomon, R. D.
Bliesner, L. A. Hardy, T. A. Howell, and D. E. Eisenhauer. 1997.
Irrigation performance measures: Efficiency and uniformity. Journal
of Irrigation and Drainage Engineering. November.
Chemigation, 1997. The Irrigation Association. Falls
Church, VA , USA 22042-6638
Contractor, 1999. Certified Irrigation Contractor Workbook.
Second Edition. The Irrigation Association. Falls Church, VA , USA 22042-6638
Derryberry, B. 1994. Trouble Shooting Irrigation Control
Systems. Derryberry Irrigation. Scottsdale, AZ.
Drip, 1997, 1999. Drip Irrigation in the Landscape.
The Irrigation Association. Falls Church , VA , USA 22042-6638
Efficiency, 1997. High Efficiency Design. The
Irrigation Association. Falls Church , VA , USA 22042-6638
Hess, T.M., (Editor) 1999. Glossary of Soil Water and Plant
Terminology. Institute of Water and Environment. Cranfield University.
Silsoe, Bedford UK. (See
www.silsoe.cranfield.ac.uk/watermanagement/documents/glossary.pdf.
Head Layout, 1998. Advanced Head Layout and Zoning. The
Irrigation Association. Falls Church , VA , USA 22042-6638
ITRC, 2001. Pump efficiency Testing. Irrigation Training
and Research Center, California Polytechnic State University. San Luis Obispo,
CA 93407
James, L. G. 1988. Principles of Farm Irrigation System
Design. John Wiley and Sons.
Jensen, M. E., Editor. 1980. Design and Operation of Farm
Irrigation Systems. American Society of Agricultural Engineers. St. Joseph,
MI.
Keesen, L., 1995. The Complete Irrigation Workbook.
Franzak & Foster, div. of G.I.E., Inc.
Landscape, 1996. Landscape Irrigation Auditor Training Manual.
The Irrigation Association. Falls Church, VA , USA 22042-6638
Landscape, 2000. Landscape Irrigation Auditor Training Manual
The Irrigation Association . Falls Church, VA 22042-6638.
LD, 1977. Landscape Drainage. The Irrigation Association.
Falls Church, VA , USA 22042-6638
Monroe, B.R. 1993. Precipitation Rates and Sprinkler
Irrigation (Instructor's Manual). Hunter Industries Irrigation Design
Education Module. Hunter Industries. San Marcos, CA.
Monroe, B.R., 1995. Irrigation Hydraulics.
(Instructor's Manual). Hunter Industries Irrigation Design Education Module.
Hunter Industries. San Marcos, CA.
NRCS, 1997. Glossary and References, Chapter 17. Irrigation
Guide, National Engineering Handbook. USDA, Natural Resource
Conservation Service. Washington, DC.
Oliphant, Joe C. 1989. Modeling Sprinkler Coverage with the
SPACE Program. CATI Publication No. 890802. Center for Irrigation
Technology. California State University. Fresno, CA.
On-Farm Irrigation Committee. 1978. Describing Irrigation
Efficiency and Uniformity.
Journal of Irrigation and Drainage Division. IR1, March, 1978.
ASCE.
Physics, 1962. Physics for Students of Science and
Engineering, Part I. R. Resnick and D. Halliday. Wiley.
Predicting, 2000. Predicting and Estimating Landscape Water
Use. 2000. The Irrigation Association. Falls Church, VA.
Pumps, 1996. Understanding Pumps. The Irrigation
Association. Falls Church, VA , USA 22042-6638
Pumps, 1998. Understanding Pumps, Controls and Wells.
The Irrigation Association. Falls Church, VA , USA 22042-6638
RainBird, 1997. Landscape Irrigation Products 1997-1998
Catalog. Glendora, CA.
Reference Manual. Certification Program Reference Manual for
Step 2 & 3 Examinations. 1998. The Irrigation Association. Falls
Church, VA , USA 22042-6638
Rochester, E.W. 1995. Landscape Irrigation Design.
ASAE. St. Joseph, Michigan.
Scheduling, 1999. Sprinkler System Scheduling.
The Irrigation Association. Falls Church , VA , USA 22042-6638
Schwab, G.O., D.D. Fangmeier, W.J. Elliot, and R.K. Frevert.
1993. Soil and Water Conservation Engineering , fourth ed. John Wiley and Sons.
Soil Fertility and Fertilizers, 1975. Tisdale, S.L. and
W. L. Nelson. 3rd edition. Macmillan Publishing Co. New York.
Smith, S.W., 1997. Landscape Irrigation. John Wiley &
Sons. New York.
Snedecor, G. W. and W. G. Cochran. 1967. Statistical Methods.
Iowa State University Press. Ames, Iowa.
Soil, 1996. Glossary of Soil Science Terms 1996. 1997.
Soil Science Society of America.
Solomon, Kenneth H. 1988. A New Way to View Sprinkler
Patterns. CATI Publication No. 880802. Center for Irrigation Technology.
California State University. Fresno, CA.
Solomon, Kenneth H., David F. Zoldoske, and Joe C. Oliphant.
Laser Optical Measurement of Sprinkler Drop Sizes. CATI Publication No.
961101. Center for Irrigation Technology. California State University. Fresno,
CA.
Zoldoske, D. F., K. H. Solomon, and E.M. Norum. 1994. CATI
Publication No. 941102. Center for Irrigation Technology. California State
University. Fresno, CA.
USC, 1998. An Introduction to Cross Connection. Foundation
for Cross-Connection Control and Hydraulic Research. University of Southern
California. Los Angeles, CA. (www.usc.edu/dept/fccchr/intro.html)
USDA, 1993. USDA Soil Conservation Service. National Engineering
Handbook, Part 623, Ch 2 Irrigation Water Requirements.
Webster, 1981. Webster's New Collegiate Dictionary.
G. C. Merriam Company. Springfield, Massachusetts.
Weinberg, S.S. and J.M. Roberts (Editors) 1988. The Handbook of
Landscape Architectural Construction. Volume Three Irrigation. Landscape
Architecture Foundation. Washington, DC.
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