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
843
Water parting, Drainage divide, Divide, Watershed divide, Watershed boundary, Topographic divide
A summit or boundary line separating adjacent drainage basins.
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844
Phreatic divide
An underground divide that fixes the boundary of the area that contributes groundwater to each stream system (illustrated)......
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997
Free groundwater, Phreatic water, or Non-artesian water
Groundwater having a water table, as opposed to groundwater confined by an impervious or semipervious formation at its upper boundary......
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1032
Groundwater divide
1 - A line on a water table on each side of which the water table slopes downward in a direction away from the line. 2 - The boundary of the cone of pumping depression......
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1069
Belt of fluctuation of water table, or Belt of phreatic fluctuation
A part of the lithosphere that, because of the fluctuation of the water table, lies a part of the time in the zone of saturation and a part of the time in the overlying zone of aeration......
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1070
Cycle of fluctuation, or Phreatic cycle
The total time occupied by a period of rise and a succeeding period of decline of a water table. The most common kinds of cycles are daily, annual, and secular......
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1072
Phreatic decline, or Decline of water table
The downward movement of the water table.
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1075
Phreatic fluctuation, or Fluctuation of water table
The alternate upward and downward movement of the water table.
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1078
Highest stage of the water table, or Phreatic height
At a given place and for a given cycle of fluctuation, it is the highest elevation reached by the water table.
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1087
Phreatic low, or Lowest stage of the water table
The lowest level reached by the water table at a given place and for a given cycle of fluctuation.
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1088
Phreatic surface
1 - The upper limit of the zone of a groundwater body. 2 - See 2607 and 5269.
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1143
Zone of fluctuation of water table, or zone of phreatic fluctuations
The zone through which the water table fluctuates from its highest to its lowest level within the formation, in response to the discharge and recharge conditions......
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2239
Divide wall, Divide groyne, Division wall, or Dividing wall
A longitudinal wall or groyne separating the undersluices pocket section from the weir or barrage section (illustrated).
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2607
Line of seepage, or Phreatic surface
1 - The surface separating the saturated ground and where seepage occurs from the unsaturated ground above it. 2 - See 1088 and 5269......
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2864
Splitter wall, Divider wall, or Vanes
Longitudinal walls provided in open channels or basin expansions, for recovery of head and equalization of outlet velocity or reduction in expansion length......
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3473
Distributor, Divisor, or Divider
1 - A structure built on a canal to distribute its flow either between two or more offtakes at the end of a canal or between itself and one or more offtakes; the division of flow remaining unaffected by the water level on the downstream of the structure in each channel. 2 - See 3933......
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3474
Proportional distributor, Proportional divisor, or Proportional divider
A distributor that divides the flow either in a constant proportion or in variable proportions.
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3475
Fixed proportional distributor, Fixed proportional divisor, or Fixed proportional divider
A proportional distributor tht divides the flow in a constant proportion (illustrated).
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3476
Regulated proportional distributor, Regulated proportional divisor, or Regulated proportional divider
A proportional distributor identical with the fixed proportional distributor except that the splitter is mobile instead of being fixed and its manipulation enables the flow to be divided in desired proportions; for instance, Neyrpic flow divisor (illustrated)......
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3477
Preferential distributor, Preferential divisor, or Preferential divider
A distributor built on a canal where two or more canals take off to divide the flow such that one offtake canal draws almost constant discharge irrespective of the variations of discharge in the parent channel, but other offtake canal or canals and the parent channel divide the balance discharge in constant proportions (Example of the offtake canal.....
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3480
Take-off distributor, Take-off divisor, or Take-off divider
Device placed in the offtake structure where volume of water to be diverted is only a small fraction of the water flowing in the parent channel, the volume drawn is generally constant in spite of the variations in flow and water levels in the parent channel. Except in small variations of water levels in the parent channel, the water level upstream .....
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4235
Depleted phreatic surface, or Depleted water table
A phreatic surface or water table lowered by over-pumping a non-artesian well.
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5268
Phreatic water
Groundwater occurring in the zone of saturation in an aquifer or soil profile under atmospheric conditions.
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5269
Phreatic surface
1 -The level to which water will rise in an unconfined aquifer under atmospheric conditions. 2 - See 1088 and 2607.
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