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
1626
B horizon
Is a mineral horizon in which rock structure is obliterated or is but faintly evident, characterized by one or more of the following features: a) an illuvial cementation of silicate clay, iron, alumininum, or organic matter, above or in combination; b) a residual concentration of sesquioxides relative to source materials; c) an alteration of materi.....
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2787
Baby siphon type water seal, or Maramsilli baby siphon type water seal
A water seal provided by a baby siphon which by virtue of being at a lower level gets primed earlier and its issuing jet itself seals the downstream end of the siphon duct. A siphon employing this device is also called a `Maramsilli baby siphon` (illustrated)......
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2788
Baby siphon, or Maramsilli baby siphon
A smaller siphon operating at a lower level than the main siphon in the Maramsilli baby siphon. Sometimes, the baby siphon is also referred to as `Maramsilli baby siphon` (illustrated)......
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7024
Bacillariophyta
Diatoms.
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7095
Bacillus
A rod-shaped bacterium.
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7985
Back of levee, Air side of levee, Land side of levee, Outflow side of levee, Inner side of levee, Polder side of levee, or Down stream side of levee
The side of a levee away from the river, facing the protected area.
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1511
Back shore
The part of the shore covered by water during exceptional storms only, especially when combined with exceptionally high water; the zone of the shore lying between the foreshore and the coastline, and acted upon by waves only during severe storms......
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4413
Back washing, or Back blowing
A method of well development based on the principle of surging or agitating the formation at the well by water or air pressure to prevent bridging of sand particles and to remove a large portion of the finer material......
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8411
Back-end
Any software performing either the final stage in a process, or a task not apparent to the user. A common usage is in a compiler. A compiler`s back-end generates machine language and performs optimisations specific to the machine`s architecture. The term can also be used in the context of network applications......
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4851
Back-washing or Back-flushing
A method of cleaning a filter that consists in reversing the direction of the flow in such a way as to carry away the solid particles collected in the filter without dismantling it......
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7997
Backfill
The placement of fill material within a specified depression, hole or excavation pit below the surrounding adjacent ground level, as a means of improving flood water conveyance, or to restore the land to the natural contours existing prior to excavation......
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3223
Backfill
1 - Earth or other material placed behind linings or structures. 2 - Replacement of excavated material.
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5405
Backfilling
The process of refilling a trench or an excavation around a structure.
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7106
Background concentration
The pollutant concentration that would remain if all emissions from all sources that are quantified for use in a modelling or calculation process were fully stopped......
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7466
Background incidence
The level of incidence of a disease that is endemic to a region, when epidemics of the disease are not occurring.
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7107
Background level
A pollutant level that is representative of average conditions in a given area.  
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7235
Background radiation
The radiation normally present in the lower atmosphere; from cosmic rays and earth-sources.
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5068
Backhoe, Backshovel
1 - Light pullback digging shovel mounted on power driven engine with wheels similar to those of farmland tractor, and fitted in the front with a loading bucket. 2 - An excavator fitted with a hinged arm to which a digging bucket is attached and operated towards the machine for excavation and away for disposal. 3 - See 6115......
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6328
Backscattering
The scattering of radiant energy into the hemisphere of space bounded by a plane normal to the direction of the incident radiation and lying on the same side as the incident. In radar usage, backscatter generally refers to that radiation reflected back toward the source......
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6416
Backslope
The hillslope position that forms the steepest, and generally linear middle portion of the slope.  In profile, backslopes are bounded by a convex shoulder above and a concave footslope below......
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1415
Backwater
1 - Water held or forced back as a consequence of some obstruction, such as a dam or regulator, or the swelling up of the river below. 2 - A water reserve obtained at high tide and discharged at low tide......
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1416
Backwater curve
The shape of the surface of water in a stream or open conduit along a longitudinal profile from a point where such a water surface is raised above its normal level by a structure such as a dam. A curve, which is usually concave upwards, may extend to several miles upstream of the obstruction. The term is also used to denote all water surface profil.....
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1417
Backwater effect
The rise in elevation of the surface profile of a stream when the flow is retarded above a dam or any other obstruction, or is backed up into a tributary by a flood in the main stream......
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5406
Backwater gate
Gate installed at the end of a tube, canal, or drain, which gets closed to prevent the downstream water from backing up into them (See also 5417)......
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7087
Bacteria
Single-celled micro-organisms that lack chlorophyll; neither plants nor animals.
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