Water terms starting with I

125 terms

Ice Boom A floating structure designed to retain ice.
Ice Bridge A continuous ice cover of limited size extending from shore to shore like a bridge.
Ice Gorge The gorge or opening left in a jam after it has broken.
Ice Jam A stationary accumulation that restricts or blocks streamflow.
Ice Push Compression of an ice cover particularly at the front of a moving section of ice cover.
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.
Ice Shove On-shore ice push caused by wind, and currents, changes in temperature, etcetera.
Ice Twitch Downstream movement of a small section of an ice cover. Ice twitches occur suddenly and often appear successively.
Ichthyology The science or study of fish.
IFLOWS The Integrated Flood Observing and Warning System.
Igneous Rock formed by molten magma. Rock that forms from the solidification of molten rock or magma.
Impact The effect, influence, alteration, or imprint caused by an action.
Impeller An agitator that is used for mixing the contents of a bioreactor.
Impermeable Refers to a rock matrix that water cannot infiltrate.
Impervious Not permeable; not allowing liquid to pass through. Resistant to movement of water.
Impervious core. See core.
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…
Impervious zone. See core.
Impinge To collide or strike.
Implementation process Procurement, installation, and implementation of all the components of an Early Warning System; includes inspecting and exercising the system.
Import Data brought into an environment or application which has been exported from another environment or application.
Impoundment A body of water confined by a dam, dike, floodgate or other artificial barrier.
Improvement Any building, structure, place, work of art, or other object constituting a physical betterment of real property, or any part of such betterment.
In situ (in si'too) the natural or normal place; confined to the site of origin without invasion or spread to neighboring tissues.
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…
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…
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…
Inches of Runoff The volume of water from runoff of a given depth over the entire drainage.
Incident command system The combination of facilities, equipment, personnel, procedures, and communications operating within a common organizational structure to effectively…
Incised stream A stream that has cut its channel into the bed of the valley through degradation.
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.
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…
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…
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…
Independent System Operator (ISO) An independent, Federally regulated entity established to coordinate regional transmission in a non-discriminatory manner and ensure the safety and…
Index of Wetness The ratio of precipitation for a given year over the mean annual precipitation.
Indicator Organism, species, or community which indicates certain environmental conditions.
Indigenous Native to a given area.
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.
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.
Industrial waste dam An embankment dam, usually built in stages, to create storage for the disposal of waste products from an industrial process.
Infiltration Leakage of ground water into a sewage collection system.
Infiltration Capacity The maximum rate at which water can enter the soil at a particular point under a given set of conditions.
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…
Infiltration gallery A horizontal conduit for intercepting and collecting ground water by gravity flow.
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…
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.
Inflow Water (and pollutants) that enter sewage systems through street inlets, roof drains, and similar sources.
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…
Influent Wastewater going into the sewage treatment plant.
Influent Seepage Movement of gravity water in the zone of aeration from the ground surface toward the water table.
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.
Initial Detention The volume of water on the ground, either in depressions or in transit, at the time active runoff begins.
Initial Loss In hydrology, rainfall preceding the beginning of surface runoff. It includes interception, surface wetting, evaporation and infiltration unless otherwise…
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…
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…
Initial SEED examination The first formal onsite examination. See evaluation report and SEED examination.
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…
Inland freshwater wetlands Swamps, marshes, and bogs found inland beyond the coastal saltwater wetlands.
Inlet channel (inlet structure) Concrete lined portion of spillway between approach channel and gate or crest structure.
Inlet structure. See inlet channel.
Inorganic Substances that are of mineral origin. See organic.
Installed capacity The total capacity of electrical generation devices in a power station or system.
Instantaneous Unit Hydrograph The theoretical, ideal, unit hydrograph that has a infinitesimal duration.
Institutionalized populations People in schools, hospitals, nursing homes, prisons, federal buildings, or other facilities that require special care or consideration during emergencies…
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.
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…
Instream uses Water uses that can be carried out without removing the water from its source, as in navigation and recreation.
Instrumentation Any device used to monitor the performance of the structure during its construction and throughout its useful life.
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.
Intake structure Concrete portion of an outlet works, including trashracks and/or fish screens, upstream from the tunnel or conduit portions.
Intangible factors Factors that affect a decision, but that cannot be expressed in monetary terms.
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…
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.
Integrated Flood Observing and Warning System (IFLOWS) A 1200 baud wide area network utilizing UHF/VHF radio and land line communications; IFLOWS components include rainfall and stage sensors, transceivers…
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…
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…
Interbasin Transfer The physical transfer of water from one watershed to another.
Intercepting Drain Curtain drain.
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…
Interception Storage Requirements Water caught by plants at the onset of a rainstorm. This must be met before rainfall reaches the ground.
Interconnected system System consisting of two or more individual power systems normally operating with connecting tie lines.
Interflow Lateral movement of water in the upper layer of soil.
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…
Intermediate SEED examination An onsite examination performed approximately every 3 years, or more frequently if conditions dictate, to evaluate the operation, performance, and…
Intermediate Zone The subsurface water zone below the root zone and above the capillary fringe.
Intermittent capacity The load carrying capability of a generator having less than full availability for meeting loads over specific periods of time.
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…
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.
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…
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.
Internal Erosion The formation of voids within soil or soft rock caused by the mechanical or chemical removal of material by seepage. See erosion.
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.
Interruptible demands Demands that, by contract, can be interrupted if the supplying system lacks capacity.
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…
Interstice An opening or space in a rock or soil. See void.
Interstitial flow Portion of surface water that infiltrates the streambed and moves through pores in subsurface.
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.
Intrados The curved downstream surface of horizontal arch elements of an arch dam. See extrados.
Intrusion A feature (landform, vegetation, or structure) that is generally considered out of context because of excessive contrast and disharmony with…