Water — page 16 of 31

Water terms

1501. Hummocked Ice Ice piled haphazardly one piece over another to form an uneven surface.
1502. Humus Decayed organic matter. A dark fluffy swamp soil composed chiefly of decayed vegetation.
1503. Hydraucone A draft tube in which the emerging water impinges on a plate.
1504. Hydraulic Powered by water. Having to do with water in motion.
1505. Hydraulic efficiency Efficiency of a pump or turbine to impart energy to or extract energy from water.
1506. Hydraulic fill Fill material that is transported and deposited using water.
1507. Hydraulic Fill Dam An embankment dam constructed of materials, often dredged, which are conveyed and/or placed by suspension in flowing water.
1508. Hydraulic fill structure A dam or impoundment made of hydraulic fill.
1509. Hydraulic Grade Line A line whose plotted ordinate position represents the sum of pressure head plus elevation head for the various positions along a given fluid flow path…
1510. Hydraulic grade line (HGL) (Hydraulic gradient) The hydraulic grade line lies below the energy grade line by an amount equal to the velocity head at the section.
1511. Hydraulic Head (1) The height of the free surface of a body of water above a given point beneath the surface.
1512. Hydraulic height Height to which the water rises behind the dam, and is the difference between the lowest point in the original streambed at the axis or the centerline…
1513. Hydraulic Mean Depth The right cross-sectional area of a stream of water divided by the length of that part of its periphery in contact with its containing conduit; the ratio…
1514. Hydraulic Permeability The flow of water through a unit cross-sectional area of soil normal to the direction of flow when the hydraulic gradient is unity.
1515. Hydraulic Radius The right cross-sectional area of a stream of water divided by the length of that part of its periphery in contact with its containing conduit; the ratio…
1516. Hydraulics Having to do with the mechanical properties of water in motion and the application of these properties in engineering.
1517. Hydric Characterized by, or thriving in, an abundance of moisture.
1518. Hydroelectric plant Electric powerplant using falling water as its motive force. A power plant that produces electricity from the power of rushing water turning…
1519. Hydroelectric power The generation of electricity using falling water.
1520. Hydroelectric unit (hydrounit) An electric generator and turbine combination which is driven by water flow, thereby converting mechanical energy to electric energy.
1521. Hydrogeochemistry Chemistry of ground water and surface water.
1522. Hydrogeologic conditions Conditions stemming from the interaction of ground water and the surrounding soil and rock.
1523. Hydrogeologic cycle The natural process of recycling water from the atmosphere down to (and through) the earth and back to the atmosphere again.
1524. Hydrogeologist A person who studies and works with ground water.
1525. Hydrogeology The geology of ground water, with particular emphasis on the chemistry and movement of water.
1526. Hydrograph A graphical representation of the stage or discharge as a function of time at a particular point on a watercourse; a time-discharge curve of the unsteady…
1527. Hydrograph Separation The process where the storm hydrograph is separated into baseflow components and surface runoff components.
1528. Hydrographic Survey An instrumental survey to measure and determine characteristics of streams and other bodies of water within an area, including such things as location…
1529. Hydrography Scientific study of physical aspects of all waters on the Earth's surface. Water features in 7.
1530. Hydrologic Budget An accounting of the inflow to, outflow from, and storage in, a hydrologic unit, such as a drainage basin, aquifer, soil zone, lake, reservoir, or…
1531. Hydrologic Cycle Cycle of water movement from atmosphere to Earth by precipitation and its return to the atmosphere by interception, evaporation, runoff, infiltration…
1532. Hydrologic Equation The water inventory equation (Inflow = Outflow + Change in Storage) which expresses the basic principle that during a given time interval the total inflow…
1533. Hydrologic Model A conceptual or physically-based procedure for numerically simulating a process or processes which occur in a watershed.
1534. Hydrologic Operations Division (HOD) (HOD) The Hydrologic Operations Division of the Office of Hydrology (OH).
1535. Hydrologic Service Area (HSA) (HSA) A geographical area assigned to Weather Service Forecast Office's/Weather Forecast Office's that embraces one or more rivers.
1536. Hydrologic Services A general term referring to the operations, products, verbal communications, and related forms of support provided by the NWS for the Nation's streams…
1537. Hydrologic Systems Branch (HSB) (HSB) The Hydrologic Systems Branch in the Office of Hydrology (OH).
1538. Hydrologic Unit A geographical area representing part or all of a surface drainage basin or distinct hydrologic feature such as a reservoir, lake, etc.
1539. Hydrologic unit code An eight-digit number used to identify a geographic area representing part or all of a surface drainage basin or distinct hydrologic feature.
1540. Hydrological Research Laboratory (HRL) (HRL) The Hydrological Research Laboratory at the Office of Hydrology (OH).
1541. Hydrologist on Duty (HOD) (HOD) The Hydrologist on Duty at an RFC.
1542. Hydrologists Individuals who study the applied science of hydrology and solve hydrologic problems.
1543. Hydrology The science dealing with the distribution, properties and circulation of water on land, in the soil, and in the atmosphere.
1544. Hydromet A system of data collection platforms that gathers hydrometeorological data, and transmits that data via GOES Satelite to a computer downlink.
1545. Hydrometeorological Automated Data System (HADS) (HADS) Software that replaced GDDS to process and distribute the GOES DCP data and CADAS data collected from DCP's and LARCS.
1546. Hydrometeorological Information Center (HIC) (HIC) The Hydrometeorological Information Center of the Office of Hydrology (OH).
1547. Hydrometeorological Report (HMR) A series of hydrometeorological reports published by the National Weather Service (NWS) addressing meteorological issues related mainly to developing…
1548. Hydrometeorological Technicians Individuals whose duties include data collection, quality control, gage network maintenance, as well as the gathering and disseminating of data and…
1549. Hydrometer A device for measuring the specific gravity of fluids.
1550. Hydrophilic Having a strong affinity (liking) for water. The opposite of hydrophobic.
1551. Hydrophobic Having a strong aversion (dislike) for water. The opposite of hydrophilic.
1552. Hydrosphere The region that includes all the earth's liquid water, frozen water, floating ice, frozen upper layer of soil, and the small amounts of water vapor in the…
1553. Hydrostatic Relating to pressure or equilibrium of fluids. The pressures and forces resulting from the weight of a fluid at rest.
1554. Hydrostatic Head A measure of pressure at a given point in a liquid in terms of the vertical height of a column of the same liquid which would produce the same pressure.
1555. Hyetograph A graphical representation of rainfall intensity with respect to time.
1556. Hyperconcentrated flow Moving mixture of sediment and water between 40 and 80 percent water by volume.
1557. Hypocenter The point or focus within the earth which is the center of an earthquake and the origin of its elastic waves.
1558. Hypolimnetic Pertaining to the lower, colder portion of a lake or reservoir which is separated from the upper, warmer portion (epilimnion) by the thermocline.
1559. Hypolimnion The lower, or bottom, layer of a lake or reservoir with essentially uniform colder temperatures.
1560. Hyporheic zone Ground water habitats created by the movement of river water from the active channel to areas to the side and beneath the active channel.
1561. Hypsography Elevation measurement system based on a sea level datum.
1562. Ice Boom A floating structure designed to retain ice.
1563. Ice Bridge A continuous ice cover of limited size extending from shore to shore like a bridge.
1564. Ice Gorge The gorge or opening left in a jam after it has broken.
1565. Ice Jam A stationary accumulation that restricts or blocks streamflow.
1566. Ice Push Compression of an ice cover particularly at the front of a moving section of ice cover.
1567. Ice Run Flow of ice in a river. An ice run may be light or heavy, and may consist of frazil, anchor, slush, or sheet ice.
1568. Ice Shove On-shore ice push caused by wind, and currents, changes in temperature, etcetera.
1569. Ice Twitch Downstream movement of a small section of an ice cover. Ice twitches occur suddenly and often appear successively.
1570. Ichthyology The science or study of fish.
1571. IFLOWS The Integrated Flood Observing and Warning System.
1572. Igneous Rock formed by molten magma. Rock that forms from the solidification of molten rock or magma.
1573. Impact The effect, influence, alteration, or imprint caused by an action.
1574. Impeller An agitator that is used for mixing the contents of a bioreactor.
1575. Impermeable Refers to a rock matrix that water cannot infiltrate.
1576. Impervious Not permeable; not allowing liquid to pass through. Resistant to movement of water.
1577. Impervious core. See core.
1578. Impervious material Relatively waterproof soils. Clay, for example, since water will percolate through clay at about one millionth of the rate at which it will pass through…
1579. Impervious zone. See core.
1580. Impinge To collide or strike.
1581. Implementation process Procurement, installation, and implementation of all the components of an Early Warning System; includes inspecting and exercising the system.
1582. Import Data brought into an environment or application which has been exported from another environment or application.
1583. Impoundment A body of water confined by a dam, dike, floodgate or other artificial barrier.
1584. Improvement Any building, structure, place, work of art, or other object constituting a physical betterment of real property, or any part of such betterment.
1585. In situ (in si'too) the natural or normal place; confined to the site of origin without invasion or spread to neighboring tissues.
1586. Inactive capacity (inactive storage) The reservoir capacity exclusive of and above the dead capacity from which the stored water is normally not available because of operating agreements or…
1587. Inactive Storage Capacity The portion of capacity below which the reservoir is not normally drawn, and which is provided for sedimentation, recreation, fish and wildlife, aesthetic…
1588. Inch-Degrees The product of inches of rainfall multiplied by the temperature in degrees above freezing (Fahrenheit Scale), used as a measure of the snowmelting…
1589. Inches of Runoff The volume of water from runoff of a given depth over the entire drainage.
1590. Incident command system The combination of facilities, equipment, personnel, procedures, and communications operating within a common organizational structure to effectively…
1591. Incised stream A stream that has cut its channel into the bed of the valley through degradation.
1592. Inclined Staff Gage A staff gage that is placed on the slope of a stream bank and graduated so that the scale reads directly in vertical depth.
1593. Inclinometer An instrument, usually consisting of a metal or plastic tube, inserted in a borehole and a sensitized monitor either lowered into the tube or fixed within…
1594. Incremental loss of life A measurement for assessing damage after a dam fails. The difference between the projected loss of life had the dam not been built and the projected loss…
1595. Independent Power Producer (IPP) Non-utility owned electric resources. A non-utility power generator that is not a regulated utility, government agency, or qualifying facility (QF) under…
1596. Independent System Operator (ISO) (ISO) An independent, Federally regulated entity established to coordinate regional transmission in a non-discriminatory manner and ensure the safety and…
1597. Index of Wetness The ratio of precipitation for a given year over the mean annual precipitation.
1598. Indicator Organism, species, or community which indicates certain environmental conditions.
1599. Indigenous Native to a given area.
1600. Indirect Flood Damage Expenditures made as a result of the flood (other than repair) such as relief and rescue work, removing silt and debris, etc.