Water — page 20 of 31

Water terms

1901. Minor Flooding A general term indicating minimal or no property damage but possibly some public inconvenience.
1902. Mission of the Hydrologic Services Program To provide river and flood forecasts and warnings for the protection of life and property and to provide basic hydrologic forecast information for the…
1903. Mission of the National Weather Service To provide weather and flood warnings, public forecasts and advisories for all of the United States, its territories, adjacent waters and ocean areas…
1904. Mitigation (measures) Methods or actions that will reduce adverse impacts from solar facility development.
1905. Mixed face In tunneling, digging in dirt and rock in the same heading at the same time.
1906. Modeling The use of statistical analysis, computer analysis, or model organisms to predict outcomes of research.
1907. Moderate Flooding The inundation of secondary roads; transfer to higher elevation necessary to save property -- some evacuation may be required.
1908. Moderate frequency flood A flood of lesser magnitude than the IDF, used for the service spillway design when supplemented by a separate auxiliary spillway.
1909. Modification Decision Analysis (MDA) The process of determining with confidence whether dam safety deficiencies exist for maximum loading conditions.
1910. Modified homogeneous earthfill dam A homogeneous earthfill dam that uses pervious material specially placed in the embankment to control seepage. See embankment dam.
1911. Modified Mercalli scale An earthquake intensity scale which has twelve divisions ranging from I (not felt by people) to XII (nearly total damage).
1912. Mohr circle A graphical representation of the stresses acting on the various planes at a given point.
1913. Moisture content (water content) The ratio of the weight of water in a soil sample to the weight of the dry soil, expressed as a percentage. See optimum moisture content.
1914. Moisture Equivalent The ratio of (1) the weight of water which the soil, after saturation, will retain against a centrifugal force 1,000 times the force of gravity, to (2)…
1915. Monocline Bend or steplike fold in rock layers where all strata are inclined in the same direction.
1916. Monocoque gate A thin-shell radial gate in which the usual skin plate and cross-beam framework are replaced by a hollow shell having an approximate elliptical cross…
1917. Monomictic Lakes and reservoirs which are relatively deep, do not freeze over, and undergo a single stratification and mixing cycle during the year.
1918. Morning glory spillway A circular or glory hole form of a drop inlet spillway. Usually free standing in the reservoir and so called because of its resemblance to the morning…
1919. Motor efficiency The ratio of energy delivered by a motor to the energy supplied to it during a fixed period or cycle.
1920. Movable Bed A stream bed made up of materials readily transportable by the stream flow.
1921. Moveable Bed Streams These are most common in the arid West, where steep slopes and lack of vegetation result in a lot of erosion.
1922. MS connectors Surface delays for use when shooting with detonating cord.
1923. Muck Eight card decks used in Baccarat, 416 cards in total.
1924. Mud Generally, any soil containing enough water to make it soft. A mixture of soil and water in a fluid or weakly solid state.
1925. Mudflat A mud-covered, gently sloping tract of land alternately covered and left bare by water. The muddy, nearly level bed of a dry lake.
1926. Mudstone Fine-grained sedimentary rock formed from hardened clay and silt that lacks the thin layers typical of shale.
1927. Mulch Material spread on the ground to reduce soil erosion and evaporation of water. Any substance spread or allowed to remain on the soil surface to conserve…
1928. Multi-stage pump A pump that has more than one impeller.
1929. Multiple arch dam A buttress dam, the upstream part of which comprises a series of arches.
1930. Multiple use A combination of balanced and diverse resource uses that takes into account the long-term needs of future generations for renewable and nonrenewable…
1931. Multiple-purpose reservoir (multipurpose reservoir) A reservoir planned to operate for more than one purpose.
1932. Multiple-Use MPAs Often employed over larger areas, multiple-use areas allow for integrated management of complete marine ecosystems, usually through a zoning process.
1933. Multipurpose dam A dam constructed for two or more purposes (e.g. storage, flood control, navigation, power generation, recreation, or fish and wildlife enhancement.)
1934. Multipurpose project A project designed for irrigation, power, flood control, municipal and industrial, recreation, and fish and wildlife benefits, in any combinations of two…
1935. Multipurpose Reservoir A reservoir constructed and equipped to provide storage and release of water for two or more purposes such as flood control, power development…
1936. Municipal Use of Water The various uses of water in developed urban areas, including domestic use, industrial use, street sprinkling, fire protection, etc.
1937. Municipal utility (municipally-owned electric system) A utility that is owned and operated by a city. In most cases, municipal utility rates are set at the city level, either by the municipal administration…
1938. Municipalization The process by which a municipal entity assumes responsibility for supplying utility service to its constituents.
1939. Name plate capacity Equipment rating as required by the purchaser.
1940. Nameplate Power generation capacity of a generator that can be guaranteed under continuous operation.
1941. Nanometer (millimicron) One millionth of a millimeter.
1942. National disaster medical system A system designed to deal with extensive medical care needs in very large disasters or emergencies.
1943. National Environmental Policy Act (NEPA) (NEPA) A comprehensive federal law requiring analysis of the environmental impacts of federal actions such as the approval of grants; also requiring preparation…
1944. National Environmental Satellite, Data, and Information Service (NESDIS) (NESDIS) NESDIS collects, processes, stores, analyzes, and disseminates various types of hydrologic, meteorologic, and oceanic data.
1945. National Institute for Occupational Safety and Health (NIOSH) NIOSH is the Federal agency responsible for conducting research and making recommendations for the prevention of work-related disease and injury.
1946. National Interagency Fire Center (NIFC) The National Interagency Fire Center is the nation's support center for wildland firefighting.
1947. National Monument An area designated by the President of the United States, under the authority of the Antiquities Act of 1906, to protect objects of scientific and…
1948. National Oceanic and Atmospheric Administration (NOAA) The National Oceanic and Atmospheric Administration's mission is to describe and predict changes in the Earth's environment, and conserve and wisely…
1949. National Operational Hydrologic Remote Sensing Center (NOHRSC) (NOHRSC) The National Operational Hydrologic Remote Sensing Center. An organization under the National Weather Service Office of Hydrology (OH) that mainly deals…
1950. National Park Service (NPS) The National Park Service preserves unimpaired the natural and cultural resources and values of the national park system for the enjoyment, education, and…
1951. National Parks (U.S.) A large area of land preserved in its natural state as public property.
1952. National Pollutant Discharge Elimination System (NPDES) (NPDES) A federal permitting system controlling the discharge of effluents to surface water and regulated through the Clean Water Act, as Amended.
1953. National Register of Historic Places A federally maintained register of districts, sites, buildings, structures, architecture, archeology, and culture.
1954. National Response Center (NRC) Located at the U.S. Coast Guard Headquarters in Washington, D.C., the NRC is a 24-hour national communications center and the single point of contact for…
1955. National Response Team (NRT) NRT consists of representatives from several Federal agencies including the Department of the Interior (DOI) and the Bureau of Reclamation.
1956. National System of MPAs The group of MPA sites, networks, and systems established and managed by federal, state, territorial, tribal, and/or local governments that collectively…
1957. National Warning System (NAWAS) A dedicated, commercially leased, nationwide voice telephone warning system operated on a 24-hour basis, with a National Warning Center and an Alternate…
1958. National Water Quality Assessment Program Describes current water quality conditions for a large part of the United States freshwater stream, rivers, and aquifers.
1959. National Weather Service (NWS) The National Weather Service provides weather, hydrologic, and climate forecasts and warnings for the United States, its territories, adjacent waters and…
1960. Nationwide Rivers Inventory (NRI) The Nationwide Rivers Inventory is a listing of more than 3,400 free-flowing river segments in the United States that are believed to possess one or more…
1961. Natural Control A stream gaging control which is natural to the stream channel, in contrast to an artificial control structure by man.
1962. Natural floodway The channel of a water course and those portions of the adjoining flood plain which are reasonably required to carry a selected probability flood.
1963. Natural frequency (f) The natural frequencies of a structure are the frequencies of free vibration. Free vibration is vibration that occurs in the absence of forced vibration.
1964. Natural period of vibration (T) The period of vibration of a a structure is the time required for one cycle of the simple harmonic motion in one of these characteristic patterns (shapes).
1965. Natural Science The sciences involved in the study of the physical world and its phenomena.
1966. Naturalness Area which generally appears to have been affected primarily by the forces of nature, with the imprint of man's work substantially unnoticeable.
1967. Navigable waters Waters of the United States including: (a) All waters that are currently used, were used in the past, or may be susceptible to use in interstate or…
1968. Navigation Methods Three basic methods of providing and managing inland waterways - 1) Run-of-the-River: no provision of upstream storage; 2) Slack-Water: locks and dams…
1969. Neatlines (of structure) A line which defines the limits of work, such as an excavation, cut stone, etc.
1970. Needle valve Any of a family of valves which regulate flow through the use of a needle moving into and out of an orifice.
1971. Negative pressure Pressure within a pipe that is less than atmospheric pressure.
1972. Neoprene A synthetic rubber with superior resistance to oils; often used as gasket and washer material.
1973. Neotropic migrant (neotropical) A bird that migrates to tropical regions during the winter.
1974. Nephelometric A means of measuring turbidity in a sample by using an instrument called a nephelometer.
1975. Net capability The maximum load-carrying ability of the equipment, exclusive of station use, under specified conditions for a given time interval, independent of the…
1976. Net cut The cut required, less the fill required, at a particular station or part of a road.
1977. Net economic benefits Economic benefits less economic costs.
1978. Net fill The fill required, less the cut required, at a particular station or part of a road.
1979. Net Rainfall The portion of rainfall which reaches a stream channel or the concentration point as direct surface flow.
1980. Network of MPAs A set of discrete MPAs within a region or ecosystem that are connected through complementary purposes and synergistic protections.
1981. Neutron probe An instrument used to estimate soil moisture. Relates the rate of attenuation in pulsed neutron emissions to soil water content.
1982. New York rod A leveling rod marked with narrow lines, ruler-fashion.
1983. Newton A force which, when applied to a body having a mass of one kilogram, gives it an acceleration of one meter per second squared.
1984. Nipple In anatomy, the small raised area in the center of the breast through which milk can flow to the outside.
1985. No action alternative The projected baseline condition, or future without. The expected future condition if no action is taken (not necessarily the same as the present…
1986. No jeopardy opinion U.S. Fish and Wildlife Service (FWS) or National Marine Fisheries Service (NMFS) opinion that an action is not likely to jeopardize the continued…
1987. No-Take Zones Areas in which all extractive activities are prohibited.
1988. Nominal diameter An approximate measurement of the diameter of a pipe. Although the nominal diameter is used to describe the size or diameter of a pipe, it is usually not…
1989. Nominal dollars Dollar value in the indicated year, not adjusted for inflation.
1990. Nominal size The approximate dimension(s) of standard materials.
1991. Non-potable Water that may contain objectionable pollution, contamination, minerals, or infective agents and is considered unsafe and/or unpalatable for drinking.
1992. Non-reimbursable Cost of constructing, operating, or maintaining a Reclamation project that is borne by the Federal taxpayer and is not reimbursed by any other individual…
1993. Non-uniform flow The velocity varies with position.
1994. Non-utility generators (NUG's) Facilities for generating electricity that are not owned exclusively by an electric utility and which operate connected to an electric utility system.
1995. Nonconsumptive water uses Water uses that do not substantially deplete water supplies, including swimming, boating, waterskiing, fishing, maintenance of stream related fish and…
1996. Nonfirm commercial energy Energy periodically available for sale at lower than firm power rates. All energy which cannot be considered as firm.
1997. Nonfirm power Power that is not available continuously and may be interruptible. This power may be marketed on a short-term basis.
1998. Nonpoint source A contributing factor to water pollution that cannot be traced to a specific spot.
1999. Nonpreference customer A customer excluded by law from preference in the purchase of federally produced electrical energy.
2000. Nonterritorial communities Networks of associations around shared goals, values, and norms, such as the agricultural, environmental, or recreational community; also known as…