Water terms starting with D
- Diaphragm-type earthfill An embankment dam which is constructed mostly of pervious material and having a diaphragm of impermeable material which forms a water barrier.
- Diaphragm. (DY-uh-fram) The thin muscle below the lungs and heart that separates the chest from the abdomen.
- Diatom Single-celled or colonial algae whose cell walls are made of silica.
- Differential head (unbalanced head) The condition in which the water pressure on the upstream and downstream sides of an object differ.
- Diffuse Ice Poorly defined ice edge limiting an area of dispersed ice; usually on the leeward side of an area of floating ice.
- digitizer Device that converts analog information into a digital format; for flat graphic material, such as maps, a digitizer can either be flatbed or scanning.
- Dike A low embankment, usually constructed to close up low areas of the reservoir rim and thus limit the extent of the reservoir.
- Dilatancy The expansion of cohesionless soils when subject to shear deformation.
- Dilution Dilution occurs when a company issues additional shares of stock, and as a result the earnings per share and the book value per share decline.
- Dip The angle that a planar geologic surface, for example, a fault, is inclined from the horizontal.
- direct access The 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) A steady current that flows in one direction only. The current from batteries is an example of direct current.
- Direct Flood Damage The damage done to property, structures, goods, etc., by a flood as measured by the cost of replacement and repairs.
- Direct Runoff Water that flows over the ground surface or through the ground directly into streams, rivers, or lakes.
- Direct shear test A 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)…
- Disaster An 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 capacity The maximum amount of water that can safely released from a given waterway.
- Discharge Curve A 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 agent An agent used to assist in separating individual fine soil particles and to prevent them from flocculating when in suspension.
- Dispersion Distortion of the shape of a seismic-wave train because of variation of velocity with frequency.
- Displacement pump Reciprocating type of pump where a piston draws water into a closed chamber and then expels it under pressure.
- dissolve To enter into a solution.
- Dissolved oxygen (DO) Amount of free oxygen found in water; perhaps the most commonly employed measurement of water quality.
- Distribution The sale of securities. Also refers to a sum payable to shareholders representing their share of profits.
- Distribution (Hydro)Graph A unit hydrograph of direct runoff modified to show the proportions of the volume of runoff that occur during successive equal units of time.
- Distribution efficiency Measure of the uniformity of irrigation water distribution over a field.
- Distribution Line One 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 System That portion of an electricity supply system used to deliver electricity from points on the transmission system to consumers.
- District An entity that has a contract with the Bureau of Reclamation for the delivery of irrigation water.
- Ditch Generally, a long narrow excavation. Constructed open channel for conducting water.
- Diversion The 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 capacity The 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 dam A dam built to divert water from a waterway or stream into a different watercourse.
- Diversion inlet A 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…
- Divert To direct a flow away from its natural course.
- Divide A ridge or high area of land that separates one drainage basin from another.
- DKA Dakotas Area Office (Bismarck, ND).
- DO Designated Office the national Office or intergovernmental organization of or acting for the Contracting State designated by the applicant under Chapter I…
- Dome A structure curved both in the lengthwise and crosswise direction.
- Domestic Consumption The 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 water The 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 dam An 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 face The inclined surface of a dam away from the reservoir. See face.
- Downstream Slope The slope or face of the dam away from the reservoir water. This slope requires some kind of protection (e.g.
- Draft A 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…
- Drain In 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 Layer A layer of permeable material in a dam to relieve pore pressure or to facilitate draining fill. See also, "Blanket"
- Drainage See Watershed.
- Drainage Area The 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 Basin All 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 Blanket A layer of pervious material placed directly over the foundation material to facilitate drainage of the foundation and/or embankment.
- Drainage curtain A 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 Density The 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 Divide The boundary line, along a topographic ridge or along a subsurface formation, separating two adjacent drainage basins.
- Drainage layer A layer of pervious material in an earthfill dam to relieve pore pressures or to facilitate drainage of the fill.
- Drainage system Collection 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…
- Draw Same as to hit. Taking additional cards in an attempt to get closer to a total of 21.
- Drawdown Lowering a lake level for a specific purpose.
- Dredge To dig under water. A machine that digs under water.
- Dredging The scooping, or suction of underwater material from a harbor, or waterway. Dredging is one form of channel modification.
- Drift See: genetic drift.
- Drifting Ice Pieces 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 structure An in-stream structure of various materials designed to reduce the energy and force of stream flow.
- Drought Climatic condition in which there is insufficient soil moisture available for normal vegetative growth. A prolonged period of below-average precipitation.
- Drought Index Computed value which is related to some of the cumulative effects of a prolonged and abnormal moisture deficiency.
- Drum gate A movable crest gate in the form of a sector of a cylinder hinged at the centerline.
- Dry Crack Crack visible at the surface but not going right through the ice cover, and therefore it is dry.
- Dry Flood proofing A dry flood proofed building is sealed against floodwaters. All areas below the flood protection level are made watertight.
- Dry unit weight The weight of solid particles per unit of total volume. See unit weight.
- Dry Weather Flow Streamflow which results from precipitation that infiltrates into the soil and eventually moves through the soil to the stream channel.
- Dry well A deep hole, covered, and usually lined or filled with rocks, that holds drainage water until it soaks into the ground.
- Ductility The property of a material that allows it to be formed into thin sections without breaking.
- Dumped A method of compacting soil by dumping the soil into place with no compactive effort.
- Duration Curve A cumulative frequency curve that shows the percent of time during which specified units of items (e.g. discharge, head, power, etc.
- Duration of Ice Cover The time from freeze-up to break-up of an ice cover.
- Duration of Protection Also "Lasting Protection." Site must be established with the intent at the time of designation to provide permanent protection.
- DVA - deficiency verification analysis.
- Dynamic compaction A method of compacting soil by dropping a heavy weight onto loose soil.
- Dynamic equilibrium Condition achieved when the average sand load transported by flowing water is in balance with the sand load being supplied by tributaries.
- Dynamic Ice Pressure due to a moving ice cover or drifting ice.
- Dynamic pressure When 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) A computerized hydraulic routing program whose algorithms incorporate the complete one-dimensional equations of unsteady flow originally developed by…