Diffuse IcePoorly defined ice edge limiting an area of dispersed ice; usually on the leeward side of an area of floating ice.
digitizerDevice that converts analog information into a digital format; for flat graphic material, such as maps, a digitizer can either be flatbed or scanning.
DikeA low embankment, usually constructed to close up low areas of the reservoir rim and thus limit the extent of the reservoir.
DilatancyThe expansion of cohesionless soils when subject to shear deformation.
DilutionDilution occurs when a company issues additional shares of stock, and as a result the earnings per share and the book value per share decline.
DipThe angle that a planar geologic surface, for example, a fault, is inclined from the horizontal.
direct accessThe ability of an electric power consumer to purchase electricity from a supplier of their choice without being physically inhibited by the owner of the…
Direct current (DC)(DC)A steady current that flows in one direction only. The current from batteries is an example of direct current.
Direct Flood DamageThe damage done to property, structures, goods, etc., by a flood as measured by the cost of replacement and repairs.
Direct RunoffWater that flows over the ground surface or through the ground directly into streams, rivers, or lakes.
Direct shear testA shear test in which soil or rock under an applied normal load is stressed to failure by moving one section of the specimen container (shear box)…
DisasterAn event that demands a crisis response beyond the scope of any single line agency or service (e.g.
Discharge(DIS-charj) In medicine, a fluid that comes out of the body. Discharge can be normal or a sign of disease.
Discharge capacityThe maximum amount of water that can safely released from a given waterway.
Discharge CurveA curve that expresses the relation between the discharge of a stream or open conduit at a given location and the stage or elevation of the liquid surface…
Discharge Table(1) A table showing the relation between two mutually dependant quantities or variable over a given range of magnitude.
Dispersing agentAn agent used to assist in separating individual fine soil particles and to prevent them from flocculating when in suspension.
DispersionDistortion of the shape of a seismic-wave train because of variation of velocity with frequency.
Displacement pumpReciprocating type of pump where a piston draws water into a closed chamber and then expels it under pressure.
Dissolved oxygen (DO)Amount of free oxygen found in water; perhaps the most commonly employed measurement of water quality.
DistributionThe sale of securities. Also refers to a sum payable to shareholders representing their share of profits.
Distribution (Hydro)GraphA unit hydrograph of direct runoff modified to show the proportions of the volume of runoff that occur during successive equal units of time.
Distribution efficiencyMeasure of the uniformity of irrigation water distribution over a field.
Distribution LineOne or more circuits of a distribution system on the same line or poles or supporting structures' usually operating at a lower voltage relative to the…
Distribution SystemThat portion of an electricity supply system used to deliver electricity from points on the transmission system to consumers.
DistrictAn entity that has a contract with the Bureau of Reclamation for the delivery of irrigation water.
DitchGenerally, a long narrow excavation. Constructed open channel for conducting water.
DiversionThe process of removing some minor criminal, traffic or juvenile cases from the full judicial process, on the condition that the accused undergo some sort…
Diversion capacityThe flow which can be passed through the canal headworks at a dam under normal head.
Diversion channel (canal or tunnel)A waterway used to divert water from its natural course. The term generally applies to a temporary arrangement (e.g.
Diversion damA dam built to divert water from a waterway or stream into a different watercourse.
Diversion inletA conduit or tunnel upstream from an intake structure. Diversion inlet may be integral with the outlet works or be part of a separate conveyance structure…
DivertTo direct a flow away from its natural course.
DivideA ridge or high area of land that separates one drainage basin from another.
DODesignated Office the national Office or intergovernmental organization of or acting for the Contracting State designated by the applicant under Chapter I…
DomeA structure curved both in the lengthwise and crosswise direction.
Domestic ConsumptionThe quantity, or quantity per capita, of water consumed in a municipality or district for domestic uses or purposes during a given period, generally one…
Domestic Use of waterThe use of water primarily for household purposes, the watering of livestock, the irrigation of gardens, lawns, shrubbery, etc.
Domestic water use (residential water use)Water for household purposes, such as drinking, food preparation, bathing, washing clothes and dishes, flushing toilets, and water lawns and gardens.
Double curvature arch damAn arch dam which is curved in plan and elevation, with undercutting of the heel and in most instances, a downstream overhang near the crest.
Downstream faceThe inclined surface of a dam away from the reservoir. See face.
Downstream SlopeThe slope or face of the dam away from the reservoir water. This slope requires some kind of protection (e.g.
DraftA signed, written order by which one party (the drawer) instructs another party (the drawee) to pay a specified sum to a third party (the payee), at sight…
DrainIn medicine, to remove fluid as it collects; or, a tube or wick-like device used to remove fluid from a body cavity, wound, or infected area.
Drain LayerA layer of permeable material in a dam to relieve pore pressure or to facilitate draining fill. See also, "Blanket"
Drainage AreaThe area which drains to a particular point on a river or stream. The drainage area of a stream at a specified location is that area, measured in a…
Drainage BasinAll of the area drained by a river system. The drainage basin is a part of the surface of the earth that is occupied by a drainage system, which consists…
Drainage BlanketA layer of pervious material placed directly over the foundation material to facilitate drainage of the foundation and/or embankment.
Drainage curtainA line of vertical wells or boreholes to facilitate drainage of the foundation and abutments and to reduce water pressure (also called drainage wells or…
Drainage DensityThe relative density of natural drainage channels in a given area. It is usually expressed in terms of miles of natural drainage or stream channel per…
Drainage DivideThe boundary line, along a topographic ridge or along a subsurface formation, separating two adjacent drainage basins.
Drainage layerA layer of pervious material in an earthfill dam to relieve pore pressures or to facilitate drainage of the fill.
Drainage systemCollection of surface and/or subsurface drains, together with structures and pumps, used to remove surface or ground water.
Drainage well (relief well)Vertical wells or boreholes downstream of, or in downstream shoulder of, an embankment dam to collect and control seepage through or under the dam and so…
Drains (Relief Wells)A vertical well or borehole, usually downstream of impervious cores, grout curtains or cutoffs, designed to collect and direct seepage through or under a…
DrawSame as to hit. Taking additional cards in an attempt to get closer to a total of 21.
DrawdownLowering a lake level for a specific purpose.
DredgeTo dig under water. A machine that digs under water.
DredgingThe scooping, or suction of underwater material from a harbor, or waterway. Dredging is one form of channel modification.
Drifting IcePieces of floating ice moving under the action of wind and/ or currents.
Drip irrigation (trickle)An irrigation method in which water is delivered to or near each plant in small-diameter plastic tubing.
Drop structureAn in-stream structure of various materials designed to reduce the energy and force of stream flow.
DroughtClimatic condition in which there is insufficient soil moisture available for normal vegetative growth. A prolonged period of below-average precipitation.
Drought IndexComputed value which is related to some of the cumulative effects of a prolonged and abnormal moisture deficiency.
Drum gateA movable crest gate in the form of a sector of a cylinder hinged at the centerline.
Dry CrackCrack visible at the surface but not going right through the ice cover, and therefore it is dry.
Dry Flood proofingA dry flood proofed building is sealed against floodwaters. All areas below the flood protection level are made watertight.
Dry unit weightThe weight of solid particles per unit of total volume. See unit weight.
Dry Weather FlowStreamflow which results from precipitation that infiltrates into the soil and eventually moves through the soil to the stream channel.
Dry wellA deep hole, covered, and usually lined or filled with rocks, that holds drainage water until it soaks into the ground.
DuctilityThe property of a material that allows it to be formed into thin sections without breaking.
DumpedA method of compacting soil by dumping the soil into place with no compactive effort.
Duration CurveA cumulative frequency curve that shows the percent of time during which specified units of items (e.g. discharge, head, power, etc.
Dynamic compactionA method of compacting soil by dropping a heavy weight onto loose soil.
Dynamic equilibriumCondition achieved when the average sand load transported by flowing water is in balance with the sand load being supplied by tributaries.
Dynamic IcePressure due to a moving ice cover or drifting ice.
Dynamic pressureWhen a pump is operating, the vertical distance from a reference point (such as a pump centerline) to the hydraulic grade line.
Dynamic Wave Routing Model (DWOPER)(DWOPER)A computerized hydraulic routing program whose algorithms incorporate the complete one-dimensional equations of unsteady flow originally developed by…
E-19, Report on River Gage StationA report to be completed every 5 - 10 years providing a complete history of a river station and all gages that have been used for public forecasts since…
E-19a, Abridged Report on River Gage StationAn abridged version of an E-19, an E-19a used to be used to update the E-19 as additional information, or changes occur at the station during the…
E-3, Flood Stage ReportA form that a Service Hydrologist/ Hydrology Focal Point completes to document the dates in which forecast points are above flood stage, as well as the…
Early warning system (EWS)A designed system that will ensure timely recognition of a threatening event and provide a reliable and timely warning and evacuation of the population at…
Early warning system feasibilityStudy of the feasibility of installing some level of Early Warning System to meet the target times for alerts and warnings.
Earth dam (earthfill dam)An embankment dam in which more than 50 percent of the total volume is formed of compacted earth material generally smaller than 3-inch size.