Water — page 17 of 31

Water terms

1601. Industrial Consumption The quantity of water consumed in a municipality or district for mechanical, trade, and manufacturing purposes, in a given period, generally one day.
1602. Industrial waste dam An embankment dam, usually built in stages, to create storage for the disposal of waste products from an industrial process.
1603. Infiltration Leakage of ground water into a sewage collection system.
1604. Infiltration Capacity The maximum rate at which water can enter the soil at a particular point under a given set of conditions.
1605. Infiltration Capacity Curve A graph showing the time-variation of infiltration capacity. A standard infiltration capacity curve shows the time-variation of the infiltration rate…
1606. Infiltration gallery A horizontal conduit for intercepting and collecting ground water by gravity flow.
1607. Infiltration Index An average rate of infiltration, in inches per hour, equal to the average rate of rainfall such as that the volume of rainfall at greater rates equals the…
1608. Infiltration Rate The rate of water entry into the soil expressed as a depth of water per unit of time in inches per hour or feet per day.
1609. Inflow Water (and pollutants) that enter sewage systems through street inlets, roof drains, and similar sources.
1610. Inflow design flood (IDF) The flood used to design and/or modify a specific dam and its appurtenant works; particularly for sizing the spillway and outlet works, and for…
1611. Influent Wastewater going into the sewage treatment plant.
1612. Influent Seepage Movement of gravity water in the zone of aeration from the ground surface toward the water table.
1613. Influent Stream Any watercourse in which all, or a portion of the surface water flows back into the ground namely the, vadose zone, or zone of aeration.
1614. Initial Detention The volume of water on the ground, either in depressions or in transit, at the time active runoff begins.
1615. Initial Loss In hydrology, rainfall preceding the beginning of surface runoff. It includes interception, surface wetting, evaporation and infiltration unless otherwise…
1616. Initial Moisture Deficiency The quantity, usually expressed in depth of water in inches upon a unit area, by which the actual water content of a given soil zone (usually the root…
1617. Initial responders (first responders) Individuals who are likely to witness or discover a hazardous substance release and who have been trained to initiate an emergency response sequence by…
1618. Initial SEED examination The first formal onsite examination. See evaluation report and SEED examination.
1619. Initial Water Deficiency The quantity, usually expressed in depth of water in inches upon a unit area, by which the actual water content of a given soil zone (usually the root…
1620. Inland freshwater wetlands Swamps, marshes, and bogs found inland beyond the coastal saltwater wetlands.
1621. Inlet channel (inlet structure) Concrete lined portion of spillway between approach channel and gate or crest structure.
1622. Inlet structure. See inlet channel.
1623. Inorganic Substances that are of mineral origin. See organic.
1624. Installed capacity The total capacity of electrical generation devices in a power station or system.
1625. Instantaneous Unit Hydrograph The theoretical, ideal, unit hydrograph that has a infinitesimal duration.
1626. Institutionalized populations People in schools, hospitals, nursing homes, prisons, federal buildings, or other facilities that require special care or consideration during emergencies…
1627. Instream flow requirements Amount of water flowing through a defined stream channel needed to sustain instream values, e.g. flows designated for fish and wildlife.
1628. Instream use The use of water that does not require withdrawal or diversion from its natural watercourse; for example, the use of water for navigation, recreation, and…
1629. Instream uses Water uses that can be carried out without removing the water from its source, as in navigation and recreation.
1630. Instrumentation Any device used to monitor the performance of the structure during its construction and throughout its useful life.
1631. Intake The step in juvenile process during which a decision is made either to detain the juvenile at a detention center or to release to the parents.
1632. Intake structure Concrete portion of an outlet works, including trashracks and/or fish screens, upstream from the tunnel or conduit portions.
1633. Intangible factors Factors that affect a decision, but that cannot be expressed in monetary terms.
1634. Intangible Flood Damage Estimates of the damage done by disruption of business, danger to health, shock, and loss of life and in general all costs not directly measurable which…
1635. Integrated early warning system A flood warning system tied into adjacent systems so that multiple users can access the basin data and monitor the event.
1636. Integrated Flood Observing and Warning System (IFLOWS) (IFLOWS) A 1200 baud wide area network utilizing UHF/VHF radio and land line communications; IFLOWS components include rainfall and stage sensors, transceivers…
1637. Integrated resource planning (IRP) A public planning process and framework within which the costs and benefits of both demand and supply side resources are evaluated to develop the least…
1638. Intensity scale An arbitrary scale to describe the degree of shaking at a particular place. The scale is not based on measurement, but on assessment by an experienced…
1639. Interbasin Transfer The physical transfer of water from one watershed to another.
1640. Intercepting Drain Curtain drain.
1641. Interception The process by which precipitation is caught and held by foliage, twigs, and branches of trees, shrubs, and other vegetation, and lost by evaporation…
1642. Interception Storage Requirements Water caught by plants at the onset of a rainstorm. This must be met before rainfall reaches the ground.
1643. Interconnected system System consisting of two or more individual power systems normally operating with connecting tie lines.
1644. Interflow Lateral movement of water in the upper layer of soil.
1645. Interlock An electrical switch, usually magnetically operated. Used to interrupt all (local) power to a panel or device when the door is opened or the circuit…
1646. Intermediate SEED examination An onsite examination performed approximately every 3 years, or more frequently if conditions dictate, to evaluate the operation, performance, and…
1647. Intermediate Zone The subsurface water zone below the root zone and above the capillary fringe.
1648. Intermittent capacity The load carrying capability of a generator having less than full availability for meeting loads over specific periods of time.
1649. Intermittent Stream A stream that flows for a portion of the year but occasionally is dry or reduced to a pool stage when losses from evaporation or seepage exceed the…
1650. Intermittent stream (seasonal stream) A stream which flows part of the time, usually after rainstorm, during wet weather, or for only part of the year. Also referred to as an ephemeral stream.
1651. Internal combustion plant A plant in which the prime mover is an internal combustion engine. An internal combustion engine has one or more cylinders in which the process of…
1652. Internal drainage Movement of water down through soil to porous aquifers or to surface outlets at lower elevations. Drainage within a basin that has no outlet.
1653. Internal Erosion The formation of voids within soil or soft rock caused by the mechanical or chemical removal of material by seepage. See erosion.
1654. Internal vibration A method of consolidating soil in which vibrators are used within a thoroughly wetted soil mass to consolidate the soil to the desired density.
1655. Interruptible demands Demands that, by contract, can be interrupted if the supplying system lacks capacity.
1656. Interruptible load Energy loads that can be shut off or disconnected at the supplier's discretion or as determined by a contractual agreement between the supplier and the…
1657. Interstice An opening or space in a rock or soil. See void.
1658. Interstitial flow Portion of surface water that infiltrates the streambed and moves through pores in subsurface.
1659. Intertidal Refers to the environment between high and low tides (mean high water and mean low water) that is alternately exposed to the air and to the sea.
1660. Intrados The curved downstream surface of horizontal arch elements of an arch dam. See extrados.
1661. Intrusion A feature (landform, vegetation, or structure) that is generally considered out of context because of excessive contrast and disharmony with…
1662. Inundate To cover with impounded waters or floodwaters.
1663. Inundation Area Area downstream from a dam that would be subject to flooding in the event of a dam failure or large spillway release. See also, "Flood Plain".
1664. Inundation Map A map delineating the area that would be flooded by a particular flood event. It includes the ground surfaces downstream of a dam showing the probable…
1665. Invert The lowest point of an underground excavation or the lowest point of the interior of a circular conduit, pipe, or tunnel.
1666. Invertebrates All animals without a vertebral column, e.g. spiders, crabs, or worms.
1667. Investor Owned Utility (IOU) (IOU) A power provider owned by stockholders or other investors; sometimes referred to as a private power provider, in contrast to a public power provider that…
1668. Ion An atom or molecule that has lost or gained one or more electrons and has become electrically charged as a result.
1669. Iowa vane A flow deflector that will divert water in a way calculated to attract fish.
1670. Irretrievable Commitments that are lost for a period of time.
1671. Irreversible Commitments that cannot be reversed, except perhaps in the extreme long term.
1672. Irrigable acreage for service (irrigable area for service) The acreage classified as irrigable for which project works have been constructed and project water is available.
1673. Irrigable area not for service Part of the total irrigable area for which service eventually will be available but for which project facilities have not yet been constructed.
1674. Irrigable land Arable land under a specific plan for which a water supply is or can be made available and which is provided with or planned to be provided with…
1675. Irrigated acreage Irrigable acreage actually irrigated in any one year. It includes irrigated cropland harvested, irrigated pasture, cropland planted but not harvested, and…
1676. Irrigated Area The gross farm area upon which water is artificially applied for the production of crops, with no reduction for access roads, canals, or farm buildings.
1677. Irrigation The controlled application of water for agricultural purposes through manmade systems to supply water requirements that are not satisfied by rainfall.
1678. Irrigation check Small dike or dam used in the furrow alongside an irrigation border to make the water spread evenly across the border.
1679. Irrigation district A cooperative, self-governing public corporation set up as a subdivision of the State government, with definite geographic boundaries, organized and…
1680. Irrigation Efficiency The ratio of the average depth of irrigation water that is beneficially used to the average depth of irrigation water applied, expressed as a percent.
1681. Irrigation Requirement Quantity of water, exclusive of effective precipitation, that is required for crop production. See crop irrigation requirement.
1682. Isobath An imaginary line on the earth's surface or a line on a map connecting all points which are the same vertical distance above the upper or lower surface of…
1683. Isochrome A curve showing the distribution of the excess hydrostatic pressure at a given time during a process of consolidation.
1684. Isohyet A line that connects points of equal rainfall.
1685. Isothermal Having a constant temperature.
1686. Isotropic mass A mass having the same property (or properties) in all directions.
1687. Jeopardy opinion U.S. Fish and Wildlife Service (FWS) or National Marine Fisheries Service (NMFS) opinion that an action is likely to jeopardize the continued existence of…
1688. Jet-flow gate A gate consisting of a wheel-mounted leaf moved vertically by a motor-driven screw hoist.
1689. Jetting A method of compacting soil using a hose or other device, with a high velocity stream of water, worked down through the depth of soil placed.
1690. Jetting pump A water pump that develops very high discharge pressure.
1691. Jetty Pier or other structure built out into a body of water to influence the current or tide, or to protect a harbor or shoreline.
1692. Job hazard analysis (JHA) A study of a job or activity to identify hazards or potential accidents associated with each step or task, and develop solutions that will eliminate…
1693. Jogging The frequent starting and stopping of an electric motor.
1694. Joint See expansion joint, cold joint, construction joint, contraction joint, and control joint.
1695. Joint information center A single location where public information officials gather to collaborate on, and coordinate the release of, emergency public information.
1696. Joint use capacity The reservoir capacity assigned to flood control purposes during certain periods of the year and to conservation purposes during other periods of the year.
1697. Jokulhlaup An Icelandic term meaning glacier dammed lake outburst flood.
1698. Joule A metric unit of energy or work; the energy produced by a force of one Newton operating through a distance of one meter; 1 Joule per second equals 1 Watt…
1699. Jurisdiction (1) The legal authority of a court to hear and decide a case. Concurrent jurisdiction exists when two courts have simultaneous responsibility for the same…
1700. Juvenile Young fish older than 1 year but not capable of reproduction.