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V-notch weir |
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A weir that is V-shaped, with its apex downward, used to accurately measure small rates of flow. |
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Valve |
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A device used to control the flow in a conduit, pipe, or tunnel that permanently obstructs a portion of the waterway. See butterfly valve, gate valve, hollow- jet valve, and tube valve. |
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Vebe time |
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The time for concrete to fully consolidate in a Vebe cylinder. |
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Velocity |
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Rate of flow of water expressed in feet per second or miles per hour. The time rate of displacement of a fluid particle from one point to another. Velocity is a vector quantity that has magnitude and direction. |
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Visitor day |
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Twelve visitor hours which may be aggregated by one or more persons in single or multiple visits. |
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Visitor use |
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Visitor use of wilderness resource for inspiration, stimulation, solitude, relaxation, education, pleasure, or satisfaction. |
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Void |
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Space in a soil or rock mass not occupied by solid mineral matter. This space may be occupied by air, water, or other gaseous or liquid material. |
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Void ratio |
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The ratio of the volume of void space to the volume of solid particles in a given soil mass. |
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Volt |
V |
The unit of measurement of electromotive force. It is equivalent to the force required to produce a current of 1 ampere through a resistance of 1 ohm. See kilovolt. |
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Volt-ampere |
VA |
A unit of apparent power in an ac circuit containing reactance. It is equal to the potential in volts multiplied by the current in amperes, without taking phase into consideration. |
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Voltage |
E |
Electrical pressure, i.e. the force which causes current to flow through an electrical conductor. The greatest effective difference of potential between any two conductors of a circuit |
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Volume of Concrete |
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The total space occupied by concrete forming the dam structure computed between abutments and from the top to the bottom of the dam. No deduction is made for small openings such as galleries, adits, tunnels, and operating chambers within the dam structure. The volume includes all mass concrete appurtenances not separated from the dam by construction or contraction joints. Where a powerplant is located at the downstream toe of a concrete dam, the limit of concrete in the dam should be taken as the downstream face projected to the general excavated foundation surface. |
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Volume of dam |
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The total space occupied by the materials forming the dam structure computed between abutments and from the top to the bottom of the dam. No deduction is made for small openings such as galleries, adits, tunnels, and operating chambers within the dam structure. Portions of powerhouses, locks spillway, etc., may be included only if they are necessary for the structural stability of the dam. |
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Vortex |
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A revolving mass of water (whirlpool) in which the streamlines are concentric circles and in which the total head is the same. Water rotating about an axis. |
