NPDP Dam Dictionary

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Term AKA Definition
Gigawatt gw Unit of power equal to 1 billion watts.
Gigawatthour GWh One billion watthours of electrical energy.
Gradation Proportion of material of each grain-size present in a given soil
Grade The elevation of a surface or a surface slope.
Grade stake A stake indicating the amount of cut or fill required to bring the ground to a specified level.
Graded stream Streams that receive and carry away equal amounts of sediment.
Grader A machine with a centrally located blade that can be angled to cast to either side, with independent hoist control on each side.
Gradient General slope or rate of change in vertical elevation per unit of horizontal distance of water surface of a flowing stream. Slope along a specific route, as of a road surface, channel or pipe.
Grapple A clamshell-type bucket having three or more jaws.
Gravel Loose rounded fragments of rock that will pass a 3-inch sieve and be retained on a No. 4 sieve (3/16 inch).
Gravel blanket Thin layer of gravel spread over an area either of natural ground, excavated surface, or embankment.
Gravel surfacing Layer of gravel spread over an area intended for vehicular or personnel traffic, such as roads, parking lots and sidewalks.
Gravelfill Gravel used to fill holes or spaces.
Gravity dam A dam constructed of concrete and/or masonry which relies on its mass for stability. See arch-gravity dam, crib dam, curved gravity dam, cyclopean dam, and hollow gravity dam.
Gravity irrigation Irrigation method that applies irrigation water to fields by letting it flow from a higher level supply canal through ditches or furrows to fields at a lower level.
Grizzly Grizzlie A coarse screen used to remove oversize pieces from earth or blasted rock. A gate or closure on a chute.
Groin The contact between the upstream or downstream face of a dam and the abutments.
Gross crop value This value is the sum of annual receipts from sale of crops produced. Production of crops, such as pasture and hay which normally are consumed on the farm by livestock, shall be converted to cash market values and included with crop sales.
Gross generation Total amount of electrical energy produced by a generating station or stations, measured at generator terminals.
Ground motion A general term including all aspects of ground motion, namely particle acceleration, velocity, or displacement, from an earthquake or other energy source.
Groundwater Water that flows or seeps downward and saturates soil or rock, supplying springs and wells. The upper level of the saturated zone is called the water table. Water stored underground in rock crevices and in the pores of geologic materials that make up the earth's crust. That part of the subsurface water which is in the zone of saturation; phreatic water.
Grout A fluid mixture of cement and water or sand, cement, and water used to seal joints and cracks in a rock foundation.
Grout blanket An area of the foundation systematically grouted to a uniform depth.
Grout cap A concrete pad or wall constructed to facilitate subsequent pressure grouting of the grout curtain beneath the grout cap.
Grout curtain Grout Cutoff A vertical zone, usually thin, in the foundation into which grout is injected to reduce seepage beneath a dam.
Grouting Filling cracks and crevices with a cement mixture.
Grubbing Removal of stumps, roots, and vegetable matter from the ground surface after clearing and prior to excavation.
Guard gate Emergency The first gate in a series of flow controls, remaining open while downstream gates or valves are operative. A gate used in the closed position to permit servicing of the downstream regulating gate or valve.
Habitat The area or type of environment in which a plant or animal normally lives or occurs.
Halophytic Salt-loving. Plants that thrive in soils that contain salt and/or sodium. A plant that grows in salty or alkaline soil.