Water terms starting with F

203 terms

Face Exposed surface of dam materials (earth, rockfill, or concrete), upstream and downstream. The external surface which limits the structure, see neatlines.
Facilities Structures associated with Reclamation irrigation projects, municipal and industrial water systems, power generation facilities, including all storage…
Facing With reference to a wall or concrete dam, a coating of a different material, masonry or brick, for architectural or protection purposes, e.g.
Factor of safety The ratio of the ultimate strength of the material to the allowable or working stress.
Fahrenheit (F) Unit of temperature. Degrees Fahrenheit equals (9/5)x(degrees Celsius)+(32).
Failure An incident resulting in the uncontrolled release of water from a dam. Destroyed and made useless, ceases to function as a dam.
Failure potential assessment A judgment of the potential for failure of an essential element within the expected life of the project.
Fall The amount of slope given to horizontal runs of pipe.
Fallow Land plowed and tilled and left unplanted.
False set. See horsehead.
Farm loss (water) Water delivered to a farm which is not made available to the crop to be irrigated.
Fatal flaw Any problem, lack, or conflict (real or perceived) that will destroy a solution or process.
Fatality rate A multiplication factor based on the estimated severity of the flood, potential warning times, and the judgement related to the understanding of the flood…
Fault "Fault" means adultery, alcohol abuse, drug abuse, physical abuse, domestic violence, abandonment or reckless spending.
Fault-block (horst) Uplifted section of rock bounded on both sides by faults. See graben.
Faulting The movement which produces relative displacement along a fracture in rock.
Fauna The community of animals in a specific region or habitat.
FCEXEC A component of the NWSRFS FCST Program.
FCST NWSRFS Forecast Program to produce operational forecasts.
FDO Friant Dam Office (Friant, CA).
Feasibility A determination that something can be done. A feasibility report is required in some planning processes to examine the situation and determine if a…
Feasibility estimate An estimate used for determining the economic feasibility of a project, the probable sequence and cost for construction of a project, and as a guide in…
Feather In a wind energy conversion system, to pitch the turbine blades so as to reduce their lift capacity as a method of shutting down the turbine during high…
Federal Advisory Committee Act Authorizes the establishment of a system governing the creation and operation of advisory committees in the executive branch of the federal government.
Federal Emergency Management Agency (FEMA) Federal agency responsible for the emergency evaluation and response to all disasters, natural and man-made.
Federal Energy Regulatory Commission (FERC) This is an independent regulatory agency within the U.S. DOE that has jurisdiction over interstate electricity sales, wholesale electric rates, natural…
Federal organizations Agencies, departments, or their components of the Federal Government that have a role in dam safety emergency planning and preparedness (i.e.
Federal Power Act Enacted in 1920, and amended in 1935, the Act consists of three parts. The first part incorporated the Federal Water Power Act administered by the former…
Federal Power Commission (FPC) The predecessor agency of the Federal Energy Regulatory Commission (FERC). The Federal Power Commission was created by an Act of Congress under the…
Federal Snow Sampler A snow sampler consisting of five or more sections of sampling tubes, one which has a steel cutter on the end.
Feldspar Group of light-colored minerals often found as crystals in intrusive igneous rocks. The most common rock-forming mineral.
FEMA - Federal Emergency Management Agency.
FERC - Federal Energy Regulatory Commission.
Fetch The straight line distance across a body of water subject to wind forces. The distance which wind passes over water.
Field (Moisture) Capacity The amount of water held in soil against the pull of gravity.
Field capacity (field moisture capacity) Depth of water retained in the soil after ample irrigation or heavy rain when the rate of downward movement has substantially decreased, usually one to…
Field Moisture Deficiency The quantity of water, which would be required to restore the soil moisture to field moisture capacity.
Field tile Short lengths of clay pipe that are installed as subsurface drains.
File Transfer Protocol (FTP) A method of data transfer that can take place between Frame Relay Networks, and Workstations.
Fill Man-made deposits of soil and rock and/or waste material.
Fill Dam Any dam constructed of excavated natural materials or of industrial wastes.
Filter (Filter Zone) One or more layers of granular material which is incorporated in an embankment dam and is graded (either naturally or by selection) to allow seepage…
Filter cake (mud cake) A deposit of mud on the walls of a drill hole.
Financial analysis Procedure that considers only tangible factors when evaluating various alternatives.
Finding of No Significant Impact (FONSI) A document describing the reasons why the impacts of a proposed federal action are not significant.
Fines Portion of a soil finer that a No. 200 U.S. Standard sieve. Clay or silt particles in soil.
Finger drains A series of parallel drains of narrow width (instead of a continuous drainage blanket) draining to the downstream toe of the embankment dam.
Finished grade The elevation or surface of the earth after all earthwork has been completed (also finish grade). The final grade required by specifications.
Firm energy (power) Non-interruptible energy and power guaranteed by the supplier to be available at all times, except for uncontrollable circumstances.
Firm yield The maximum quantity of water that can be guaranteed with some specified degree of confidence during a specific critical period.
Firn (Snow) Old snow on top of glaciers, granular and compact and not yet converted into ice. It is a transitional stage between snow and ice. Also called Neve.
Firn Line The highest level to which the fresh snow on a glacier's surface retreats during the melting season.
Fischer & Porter Punched Tape Recorder Gage A precipitation gage which converts weight into a code disk position. The code disk position is then punched on paper tape in a binary decimal format…
Fish & Wildlife Service (FWS) The U.S. Fish and Wildlife Service is the principal Federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and…
Fish ladder (fishway) An inclined trough which carries water from above to below a dam so that fish can easily swim upstream.
Fish weir A type of fish ladder.
Fishery A term used for a lake, river or stream where people can catch fish, or even a particular kind of fish, such as a bass or trout fishery.
Fishery Closure Area A fishery closed or restricted by a government entity. Such closure prohibits fishing for commercial, recreational, or subsistence purposes.
Fishery Management Councils Regional councils which were established under the Magnuson-Stevens Fishery Conservation and Management Act.
Fishery Management Zone Areas where fishing for some or all species is prohibited to protect critical habitats, rebuild fish stocks, ensure against overfishing, or enhance…
Fishing The operation of recovering an object left or dropped in a drill hole.
Fixed amount-frequency scheduling Method of irrigation scheduling that involves water delivery at a fixed rate or a fixed volume and at constant intervals.
Fixed cone valve (Howell Bunger valve) A cylinder gate mounted with the axis horizontal. See valve.
Fixed Wheel Gate (Fixed Roller Gate, Fixed Axle Gate) A gate consisting of a rectangular leaf mounted on wheels, particularly suited for high head situations.
FKC Friant-Kern Canal.
Flail A hammer hinged to an axle so that is can be used to break or crush material.
Flange A ridge that prevents a sliding motion. A rib or rim for strength or for attachments. A rim or collar attached to one end of a pipe to give support.
Flap Gate A gate hinged along one edge, usually either the top or bottom edge. Examples of bottom-hinged flap gates are tilting gates and fish belly gates - so…
Flash Flood A sudden flood event through a valley, canyon, or wash, following a short duration, high-intensity rainfall.
Flash Flood Guidance (FFG) An internal product produced by the RFCs containing rainfall threshold values which must be exceeded in order to produce a flash flood.
Flash Flood Statement (FFS) A statement by the NWS which provides follow-up information on flash flood watches and warnings.
Flash Flood Table A table of pre-computed forecast crest stage values for small streams for a variety of antecedent moisture conditions and rain amounts.
Flash Flood Warning Flash flooding has been reported or is imminent.
Flash Flood Warning (FFW) A warning by the NWS issued to warn of flash flooding that is imminent or occurring.
Flash Flood Watch Flash flooding is possible within the designated watch area.
Flash Flood Watch (FFA) A statement by the NWS that alerts communities to the possibility of flash flooding in specified areas.
Flashboards Temporary barriers, consisting of either timber, concrete or steel, anchored to the crest of a spillway as a means of increasing the reservoir storage.
Flat slab or slab and buttress dam A buttress dam with buttresses which support the flat slab of reinforced concrete which forms the upstream face.
Flatirons Triangular-shaped landforms along mountain ranges formed by erosion of steeply inclined rock layers or hogbacks.
Fleet angle The angle between the position of a rope or cable at the extreme end wrap on a drum and a line drawn perpendicular to the axis of the drum.
Flexible pipe Pipe designed to transmit the backfill load to the soil at the sides of the pipe.
Fling Refers to a near field long period pulse from a strong ground motion resulting in a unidirectional ground heave after rupture.
Flip bucket An energy dissipator located at the downstream end of a spillway and shaped so that water flowing at a high velocity is deflected upwards in a trajectory…
Float Recording Precipitation gage A rain gage where the rise of a float within the instrument with increasing rainfall is recorded.
Floatable days The number of days during the recreation season on which it is safe to allow floating activities on recreation facilities.
Floatable flows River flows which make rafting and other floating recreation possible.
Floc Loose, open-structured mass formed in a suspension by the aggregation of minute particles.
Flocculation The process of forming flocs. A step in water filtration in which alum is added to cause particles to clump together.
Floe An accumulation of frazil flocs (also known as a "pan") or a single piece of broken ice.
Flood A general and temporary condition of partial or complete inundation of two or more acres of normally dry land area or of two or more properties (at least…
Flood boundary Line drawn or outer edge of colored (inundation) area on an inundation map to show the limit of flooding.
Flood control capacity Reservoir capacity assigned to the sole purpose of regulating flood inflows to reduce flood damage downstream. See exclusive flood control capacity.
Flood control pool (flood pool) Reservoir volume above active conservation capacity and joint use capacity that is reserved for flood runoff and then evacuated as soon as possible to…
Flood Control Storage Storage of water in reservoirs to abate flood damage.
Flood Crest The maximum height of a flood wave as it passes a location.
Flood frequency Refers to the probability (in percent) that a flood will occur in a given year.
Flood Frequency Curve (1) A graph showing the number of times per year on the average, plotted as abscissa, that floods of magnitude, indicated by the ordinate, are equaled or…
Flood Gate A gate to control flood releases from a reservoir.
Flood hydrograph A graph showing, for a given point on a stream, the discharge, height, or other characteristic of a flood with respect to time.
Flood irrigation Water is pumped or brought to the fields and is allowed to flow along the ground among the crops.