Water terms starting with R

157 terms

Radial Lines converging at a single center.
Radial gate A pivoted crest gate, the face of which is usually a circular arc, with the center of curvature at the pivot about which the gate swings.
Radial Gate (Tainter Gate) A gate with a curved upstream plate and radial arms hinged to piers or other supporting structures on which the gate pivots.
Radioisotope Snow Gage A snow water equivalent gage based on the absorption of gamma radiation by snow; this gage can measure up to 55 inches water equivalent with a 2 to 5…
RADIUS Horizontal distance from the center of rotation.
Raffinate ponds Liquid resulting from extractions with a solvent.
Ramp flume A flume calibrated to measure the flow of liquid in an open channel.
Ramp rate The rate at power system load or generator output varies, or the limits to such rates due to mechanical or reliability considerations.
Random earthquake In addition to earthquakes that occur on mapped faults, hazards are also presented by earthquakes not associated with known geological structures.
Range Geographic region in which a given plant or animal normally lives or grows.
Rapid A section of a river where the current is very fast moving, caused by a steep descent in the riverbed through a constriction of the main channel.
Rapid flow Also refered to as supercritical flow, rapid flow is distinguished from tranquil flow by a dimensionless number called the Froude number.
Raptors Birds of prey.
Rated capacity That capacity which a hydrogenerator can deliver without exceeding mechanical safety factors or a nominal temperature rise.
Rated head Water depth for which a hydroelectric generator and turbines were designed.
Rating Curve A graph showing the relationship between the stage, usually plotted vertically (Y-axis) and the discharge, usually plotted horizontally (X-axis).
Rating Table A table of stage values and the corresponding discharge for a river gaging site.
Ratio of reduction The relationship between the maximum size of the stone which will enter a crusher, and the size of its product.
Reach Any specified length of stream, channel, or other water conveyance. A portion of a stream or a river.
Reactive Power The electrical power that oscillates between the magnetic field of an inductor and the electrical field of a capacitor.
Ready reserve Generation capacity that can be synchronized and ready to serve load in a short time period, usually 10 minutes or less.
Reattachment deposit Sand deposit located where downstream flow meets the channel bank at the downstream end of a recirculating zone.
Rebar Reinforcing steel bar. Reinforcement.
Recession Constant Constant used to reduce the API value daily in the API method of estimating runoff.
Recharge Water that infiltrates into the ground, usually from above, that replenishes groundwater reserves, provides soil moisture, and affords evapotranspiration.
Recharge rate The quantity of water per unit time that replenishes or refills an aquifer.
Recirculation zone Area of flow composed of one or more eddies immediately downstream from a constriction in the channel, such as a debris fan or rock outcrop.
Reclamation Reform Act of 1982 (RRA) The Reclamation Reform Act of 1982 limits the amount of owned land that is eligible to receive project (Reclamation) irrigation water and addresses the…
Recreation Recreational opportunities at more than 1,900 federal recreation sites managed by the Bureau of Reclamation and other federal agencies can be found at the…
Recreation Area An area that allows for recreational fishing, diving, boating, kayaking, and other recreational activities.
Recreational benefit Value of recreational activity to the recreationist, usually measured in dollars above the cost of participating in the recreational activity (travel…
Recruitment Recruitment is the process to attract the attention of individual(s) who may apply for employment.
Rectangular weir A contracted or suppressed weir with a horizontal crest, rectangular in shape, having vertical sides. See weir.
Recurrence Interval The average period in years between storm events equal to or larger than a given amount.
Redd An individual nest or depression in the gravel excavated by trout other members of the trout and salmon family for depositing eggs.
Reference Mark A relatively permanent point of known elevation which is tied to a benchmark.
Refill Material which had previously been excavated as a result of construction activities and again placed to the lines as shown on the drawings.
Reflectivity The measure of the efficiency of a radar target in intercepting and returning Electro Magnetic Energy.
Refuge compatibility requirements Requirements under the Refuge Administration Act that all uses of a national wildlife refuge must be compatible with the purpose for which the refuge was…
Region or Regional An area inclusive of and determined by participating national system sites and systems that is based on common management interests, similar or linked…
Regional Hazardous Waste Management Coordinator (HWMC) Individual designated by the Regional Director to assess and coordinate records and maintain proper management of hazardous waste activities in each…
Regional office Five Reclamation offices in the 17 Western States that supervise area, field, and project offices in their respective geographic locations.
Regional Operations Manual Letter (ROML) These serve as updates to regional policy and procedure for the National Weather Service Operations Manual (WSOM).
Regional Response Team (RRT) Regional planning and coordination of preparedness and response actions are accomplished through the RRT.
Regional Transmission Group (RTG) A voluntary organization of transmission owners, transmission users, and other entities interested in coordinating transmission planning, expansion…
Regulating dam (reregulating dam) A dam impounding a reservoir from which water is released to regulate the flow downstream. See afterbay dam.
Regulating gate (operating gate, regulating valve) A gate used to regulate the rate of flow through an outlet works or spillway. A gate or valve that operates under full pressure flow conditions to…
Regulating Gate (Regulating Valve) A gate or valve that operates under full pressure and flow conditions to throttle and vary the rate of discharge.
Regulatory Floodway Some maps show an area where construction regulations require special provisions to account for this extra hazard. This is a regulatory floodway.
Rehabilitation Any repair work that requires a permit.
Reimbursable Costs of constructing, operating, or maintaining a Reclamation project that are repaid to the Federal Government by some other individual, entity, or…
Relative density Used in construction control for cohesionless soils where the in-place density is compared to the minimum and maximum density of the soil from laboratory…
Relative Humidity A measure of the percent of moisture actually in the air compared with what would be in it if it were fully saturated at that temperature.
Release The amount of water released after use. The difference between delivery and release is usually the same as consumptive use.
Reliability The consistency of a measure or question in obtaining very similar or identical results when used repeatedly; for example, if you repeated a blood test…
Relict A land surface that was once a basin (valley) floor.
Relief Carved or molded ornament that projects from a flat surface.
Relief valve A valve which will allow air or fluid to escape if its pressure becomes higher than the valve setting.
Relief Well See drainage well.
Remote Observing System Automation (ROSA) A type of automated data transmitter used by NWS Cooperative Program observers.
Remote operation Operation of mechanical features from an on-site location other than at the feature.
remote sensing Method for determining characteristics of an object, organism or community from afar.
Renewable resources Renewable energy resources are naturally replenishable, but flow limited. They are virtually inexhaustible in duration but limited in the amount of energy…
Reportable discharge of oil (40 CFR 110.3) Harmful quantities of oil discharged or released to navigable waters of the United States are any amount that violates State water quality standards…
Reportable quantities Quantities of hazardous substances which require notification to the National Response Center and the appropriate state agency.
Reregulation dam. See afterbay dam.
Reserve generating capacity Extra generating capacity available to meet unanticipated capacity demand for power in the event of generation loss due to scheduled or unscheduled…
Reserved For purposes of the National System of MPAs, must be established by and currently subject to federal, state, commonwealth, territorial, local, or tribal…
Reserved works Facilities operated and maintained by Reclamation.
Reservoir A reservoir of an infectious agent, such as a virus, is any animal, person, plant, soil, substance—or combination of any of these — in which the…
Reservoir Area The surface area of a reservoir when filled to normal water level.
Reservoir capacity The capacity of the reservoir, usually in acre-feet. Dam design and reservoir operation utilize reservoir capacity and water surface elevation data.
Reservoir capacity allocations (RCA) sheet A summary of acre-feet allocations of water, to such purposes as surcharge, exclusive flood control capacity, joint use capacity, active conservation…
Reservoir inflow The amount of water entering a reservoir expressed in acre-feet per day or cubic feet per second.
Reservoir regulation (or operating) procedure Operating procedures that govern reservoir storage and releases.
Reservoir Surface The surface of a reservoir at any level.
Reservoir Surface Area The area covered by a reservoir when filled to a specified level.
Reservoir Volume The volume of a reservoir when filled to normal pool or water level.
Resilience Ability of any system to resist or to recover from stress or hardship.
Resource Management Plan A written plan that addresses the existing resources of an area and provides future objectives, goals, and management direction.
Response spectrum A plot of the maximum response of a series of single-degree-of-freedom damped oscillators (elastic systems) as a function of their natural periods, or…
Response Time The amount of time in which it will take a watershed to react to a given rainfall event.
Retaining wall A wall separating two levels.
Return Flow Drainage water from irrigated farmlands that re-enters the water system to be used further downstream.
Return-flow system (reuse system) A system of pipelines or ditches to collect and convey surface or subsurface runoff from an irrigated field for reuse.
Revetment An embankment or wall of sandbags, earth, etc., constructed to restrain material from being transported away. A facing of stone, cement, sandbags, etc.
Review of Operation and Maintenance (RO&M) A periodic evaluation of operation and maintenance activities at a particular facility.
Rewind Act of putting new copper insulated wire in the armature windings of a generator. Replacement of an armature (stator) winding of a synchronous generator.
RFD Razorfen Downs
Rhyolite Volcanic rock (or lava), characteristically light in color and containing 69% silica or more and generally rich in potassium and sodium (felsic…
Richter scale A scale of numerical values, proposed by C. F. Richter, to describe the magnitude of an earthquake, ranging from 1 to 9, by measurements made in…
Ridge A line or wall of broken ice forced up by pressure. May be fresh or weathered.
Ridge Ice Ice piled haphazardly one piece over another in the form of ridges or walls.
Riffle A stretch of choppy water caused by an underlying rock shoal or sandbar. A run is a long riffle.
Riffle and pool complex A water habitat composed of riffles (characterized by water flowing rapidly over a coarse substrate) and pools (deeper areas of water associated with…
Right Abutment See abutment.
Right of way The right of a party to pass over the land of another.
Right. A temporary privilege granted to existing common shareholders to purchase additional shares directly from the company at a stated price.
Rigid pipe Pipe designed to transmit the backfill load to the foundation beneath the pipe. Rigid pipe must be supported on the bottom portion of the pipe.
Rill A small and shallow incision into topsoil layers resulting from erosion by overland flow or surface runoff that is common on slopes of unvegetated ground…