International Commission on Irrigation & Drainage Commission Interationale des Irrigation et du Drainage

Multilingual Technical Dictionary (MTD)

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Term No.Term Name/Term DescriptionAction
130
Degrees of freedom
The degrees of freedom of a set of observations (ex- hypothesis are subject to sampling variation) is the number of independent values in the sample that could be assigned at will within the specification of the system......
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1653
Degree of dispersion
Extent to which soil aggregates are broken down to primary particles by any given treatment.
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1665
Degree of aggregation
Measure of the proportion in which aggregates are present.
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1720
Degree of aeration, or Air space ratio
Ratio between the volume of air and the volume occupied by the voids.
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1774
Degree of saturation (V)
Percentage ratio of exchangeable cations exclusive of H+ (= S ) to total exchangeable cations inclusive of H+ (= T ), i.e.  .....
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1802
Degree of saturation
1 - Ratio between the volume of water and the volume of voids. 2 - See 1774.
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2154
Degree of salinity
Percentage of soluble salts in the root zones.
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3227
Durability
1 - Resistance of lining to weathering, chemical attack and wearing. 2 - See 5637.
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3749
Irrigation pipe aqueduct, Pipe aqueduct, Pipe flume
An aqueduct in which the canal water is taken in a pipe over the drainage, natural stream, depression or hollows. Also called `pipe flume`......
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3756
Syphon, Inverted siphon, Irrigation syphon, Canal syphon, Syphon superpassage
1 - A structure with a closed conduit, designed to run full and usually under pressure, to transport (i) canal water under railroads, roads, various types of drainage channels and depressions, or (ii) drainage water under railroads, roads, etc. In reference to cross-drainage works on canals, this term pinpoints to the condition that the canal passe.....
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3842
Straight (line, surface) sharp cut-water, Equilateral cut-water, or Sixty degree straight sharp cut-water
A sharp cut-water formed by two straight surfaces meeting at a line. Since the two straight sides of the cut-water and the width of the pier form a triangle, it is, sometimes, classified according to triangle properties (viz. equilateral cut-water) and also according to the value of the nose angle (as 60o straight sharp cut-water)......
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3975
Lift irrigation area, or Lift area
Area interspersed between gravity flow areas where the levels are   higher than those permitted by gravity flow irrigation   from the source, but can be irrigated economically by water lifted by pumps or other water lifting devices to the required level at a certain  point in the supply system......
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4010
Continuous-flow irrigation
A system of delivery of irrigation water by which each irrigator receives his allotted quantity of water at a continuous rate throughout the growing or irrigation season......
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4032
Night-storage irrigation system
In this system practiced in Sudan, crops are not watered by night. The outlet pipes are closed at sunset but water continues to enter the tertiary canal, flow rate being the same as the one recorded during the day. At the downstream reaches of the tertiary canal, a small flat crested brick weir is constructed. A steel pipe is also provided across t.....
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4034
Intermittent-flow irrigation system
A system, in which each irrigator gets water only intermittently either by pre-established rotation of the basic flow (called module) or on demand i.e. according to the prior demands by individuals or group of individuals of the quantities and at the times that appear to them most desirable, or finally, in the most modern pressurized systems, in to.....
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4048
Irrigation return flow
That portion of the irrigation water supply which is not infiltrated into the soil, but returns to streams or rivers.  Its quality may be impaired by sediment, agricultural chemicals, or change in temperature. .....
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4065
Farm irrigation structures
Small structures and equipment that enable an irrigator to divert water from the watercourse and to convey it to various points in his field including control, regulation and measurement devices......
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4595
Collective irrigation system
A system meant to make possible the irrigation of several fields or farms of an area. It includes all or a part of the following works: storage, intake, diversion or pumping works, works for bringing water to the fields to be served, and other facilities necessary to operate the system......
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4596
Individual irrigation system
A system located downstream of the outlets served by the collective irrigation system and meant to deliver water to the farms or fields of an area......
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4597
Perennial irrigation
Irrigation of an area throughout the year
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4598
Seasonal irrigation
Irrigation of an area during only part of the year, the watering season.
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4599
Supplemental irrigation
Irrigation of an area only occasionally to supply water during irregular drought periods.
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4600
Systematic irrigation
Water applications repeated at definite intervals of time during the growing season of the crop(s).
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4601
Flow irrigation, or Gravity irrigation
Method of operating the whole or part of a system using water flow by only gravity, water being available at a sufficient level (or pressure) to ensure its conveyance and distribution in the fields......
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4602
Pumping irrigation
Method of operating a system or part of a system using, fully or partly, an artificial pressure for ensuring the conveyance of water, its delivery or distribution in the fields......
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