NPDP Dam Dictionary

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Term AKA Definition
Foreshore That part of the shore between the ordinary high-and low-watermarks and generally crossed by the tide each day.
Formation Any sedimentary, igneous, or metamorphic material represented as a unit in geology; generally called rock, but not necessarily meeting the definition of rock.
Fossorial insects Insects that live in the soil.
Foundation Lower part of a structure which transmits the load to the earth.
Foundation drains ile or pipe for collecting seepage within a foundation.
Foundation material Foundation soil The upper part of the earth mass carrying the load of the structure.
Foundation surface The surface of the upper part of the earth mass carrying the load of the structure.
Foundation trench A trench built at and into the foundation of a dam and filled with clay or other impermeable substances to prevent water from seeping beneath the dam. See cutoff trench.
Foundation type The base on which the dam is founded. In the database the foundation type is denoted as Rock, Rock & Soil, Soil, or Unlisted/Unknown.
Freeboard The difference in elevation between the maximum water surface and the dam crest. The vertical distance between a stated water level and the top of a dam. Thus net freeboard dry freeboard or flood freeboard" is the vertical distance between the maximum water surface and the top of the dam. "Gross freeboard" or "total freeboard" is the vertical distance between the normal water surface and the top of the dam. That part of the "gross freeboard" attributable to the depth of flood surcharge is sometimes referred to as the "wet freeboard but this term is not recommended as it is preferable that freeboard be stated with reference to the top of dam.
Freeze-thaw damage Damage to concrete caused by extreme temperature variations as noted by random pattern cracking. Damage is accelerated by the presence of water and commonly more severe on the south-facing side of structures.
Freezeout Deeply frozen over for long periods of time.
French drain A covered ditch containing a layer of fitted or loose stone or other pervious material
Friction Resistance to motion when one body is sliding or tending to slide over another.
Frost line The greatest depth to which ground may be expected to freeze.
Froude number The ratio of inertial forces to gravitational forces in flow. It is also the ratio of the flow velocity to the velocity of a small gravity wave in the flow. When the Froude number is less than one, the flow is tranquil. When the Froude number is greater than one, the flow is rapid. When the Froude number is equal to one, the flow is critical.
Fry Life stage of fish between the egg and fingerling stages. Depending on the species of fish, fry can measure from a few millimeters to a few centimeters.
Fuel replacement energy Electric energy generated at a hydroelectric plant as a substitute for energy which would have been generated by a thermal electric plant.
Fulcrum A pivot for a lever.
Full hydraulic capacity The designed capacity of a pipe or conduit.
Full pool Volume of water in a reservoir at normal water surface.
Furrow A natural or man-made narrow depression in the earth's surface. A narrow trenchlike plowed depression in the earth surface to keep surface water away from the slopes of cuts.
Fuse A thin core of black powder surrounded by wrappings, which when lit at one end, will burn to the other at a fixed speed. A string-like core of PETN, a high explosive, contained within a waterproof reinforced sheath. Primacord" is the best known brand."
Future without What would occur if no action were taken. See baseline condition.