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Glossary

Riparian Glossary

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
A   top
Aggradation To fill and raise the level a stream bed by deposition of sediment.
Acidic The condition of water or soil in which the amount of acid substances are sufficient to lower the pH below 7.0.
Acre A measure of area equal to 43,560 ft2 (4,046.87 m2); one square mile equals 640 acres.
Acre-Foot A quantity or volume of water covering 1 acre to a depth of 1 ft; equal to 43,560 ft3, or 325,851 gal.
Aerobic Characterizing organisms able to live only in the presence of air or free oxygen and conditions that exist only in the presence of air or free oxygen. Contrast with anaerobic.
Algae Microscopic plants that grow in sunlit water containing phosphates, nitrates, and other nutrients. Algae, like all aquatic plants, add oxygen to the water and are important in the fish food chain.
Alluvium A general term for detrital deposits made by streams on river beds, flood plains, and alluvial fans; Example: a deposit of silt or silty clay laid down during times of flood. The term applies to stream deposits of recent time.
Aquatic EcosystemThe stream channel, lake or estuary bed, water, and biotic communities and physical, chemical, and biological features that occur therein, forming a system that interacts with associated terrestrial ecosystems.
Aquatic Habitat Habitat that occurs in water.
Aquifer A water-bearing rock or rock formation.
Arid A term describing a climate or region in which precipitation is so deficient in quantity or occurs so infrequently that intensive agricultural production is not possible without irrigation.
Armoring(1) the natural process of forming an erosion-resistant layer of relatively large particles on the surface of the stream bed;
(2) the artificial application of various materials to strengthen stream banks against erosion (see also revetment).
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Bank FailureCollapse of a mass of bank material.
Bank Stability The ability of a stream bank to counteract erosion or gravity forces.
BankfullThe discharge that fills the channel without overflowing onto the flood plain.
Bankfull Channel DepthThe maximum depth of a channel within a riffle segment when flowing at a bank full discharge.
Bankfull Channel Width The top surface width of a stream channel when flowing at a bank full discharge.
Bankfull Discharge The bankfull stage corresponds to the discharge at which channel maintenance is most effective. That is, the discharge at which moving sediment, forming or removing bars, forming or changing bends and meanders, and generally doing work that results in the average morphologic characteristics of channels.
Bar A stream bed deposit of sand or gravel often exposed during low-water periods. An alluvial deposit composed of sand, gravel, or other material that obstructs flow and induces deposition or transport.
Base Flow The sustained portion of stream discharge that is drawn from natural storage sources and not affected by human activity or regulation.
Bed Load Sediment moving on or near the stream bed and transported by jumping, rolling, or sliding on the bed layer of a stream (see also suspended load).
Bed Material The sediment mixture that a stream bed is composed of.
Bed Slope The inclination of the channel bottom, measured as the elevation drop per unit length of channel.
BendA change in the direction of a stream channel in plan view.
Benthic Of or pertaining to animals and plants living on or within the substrate of a water body.
Benthic Invertebrates Aquatic animals without backbones that dwell on or in the bottom sediments of fresh or salt water. Examples: clams, crayfish, and a wide variety of worms.
Best Management Practice (BMP) A conservation measure intended to minimize or mitigate impacts from a variety of land use activities.
Bioengineering See Soil Bioengineering.
Biomass The total mass or amount of living organisms in a particular area or volume.
Biota All living organisms of a region, as in a stream or other body of water.
Blowdown Trees felled by high winds.
Bog Waterlogged ground or marshland (also known as a wetland).
Bole Trunk of a tree.
Boulder A streambed substrate particle greater than 10 inches in its longest dimension.
Braided A stream that forms an interlacing network of branching and recombining channels separated by branch islands or channel bars.
Branch Packing Live woody branch cuttings and compacted soil used to repair slumped areas of stream banks.
Brush Layer Live branch cuttings laid in crisscrossed fashion on benches between successive lifts of soil.
Brush Mattress A combination of live stakes, fascines, and live branch cuttings installed to cover and protect stream banks and shorelines.
Buffer Strip A barrier of permanent vegetation, either forest or other vegetation, between waterways and land uses such as agriculture or urban development, designed to intercept and filter out pollution before it reaches the surface water resource.
C   top
Canal A constructed open channel for transporting water.
Canopy The overhead branches and leaves of riparian vegetation.
Canopy Cover Vegetation projecting over a stream, including crown cover (generally more than 3 ft above the water surface) and overhang cover (less than 3 ft above the water surface).
Caving The collapse of a stream bank by undercutting due to wearing away of the toe or an erodible soil layer above the toe.
Channel A stream, river, or artificial waterway that periodically or continuously contains moving water. It has a definite bed and banks that confine the water.
Channelization The process of changing (usually straightening) the natural path of a waterway.
Clay Substrate particles that are smaller than silt and generally less than 0.003 mm in diameter.
Coarse Woody Debris (CWD) Portion of a tree that has fallen or been cut and left in the woods. Usually refers to pieces at least 20 inches in diameter.
Cobble Substrate particles that are smaller than boulders and larger than gravels, and are generally 64-256 mm in diameter. Can be further classified as small and large cobble.
Community Any assemblage of populations of plants and/or animals in a common special arrangement.
Confluence (1) the act of flowing together; the meeting or junction of two or more streams; also, the place where these streams meet; (2) the stream or body of water formed by the junction of two or more streams; a combined flood.
Conifer A tree belonging to the order Gymnospermae, comprising a wide range of trees that are mostly evergreens. Conifers bear cones (hence, coniferous) and have needle-shaped or scalelike leaves.
Conservation The process or means of achieving recovery of viable populations.
Conservation Area Designated land where conservation strategies are applied for the purpose of attaining a viable plant or animal population.
Conservation Recommendations Suggestions by conservation agencies regarding discretionary measures to minimize or avoid adverse effects on a proposed action of federally listed threatened or endangered species or designated critical habitat.
Conservation Strategy A management plan for a species, group of species, or ecosystem that prescribes standards and guidelines that, if implemented, provide a high likelihood that the species, groups of species, or ecosystem, with its full complement of species and processes, will continue to exist well-distributed throughout a planning area, i.e., a viable population.
Contaminate To make impure or unclean by contact or mixture.
Contiguous Habitat Habitat suitable to support the life needs of a species that is distributed continuously or nearly continuously across the landscape.
Cover Anything that provides protection for fish and/or wildlife from predators or ameliorates adverse conditions of stream flow and/or seasonal changes in metabolic costs. May be instream structures such as rocks or logs, turbulence, and/or overhead vegetation. Anything that provides areas for escape, feeding, hiding, or resting.
Critical Habitat Under the Endangered Species Act, critical habitat is defined as
(1) the specific areas within the geographic area occupied by a federally listed species on which are found physical and biological features essential to the conservation of the species and that may require special management considerations or protections;
(2) specific areas outside the geographic area occupied by a listed species, when it is determined that such areas are essential for the conservation of the species.
Critical Shear Stress The minimum amount of shear stress exerted by stream currents required to initiate soil particle motion. Because gravity also contributes to stream bank particle movement but not on stream beds, critical shear stress along stream banks is less than for stream beds.
Crown The upper part of a tree or other woody plant that carries the main system of branches and the foliage.
Crown Cover The degree to which the crowns of trees are nearing general contact with one another.
Cubic Feet Per Second (cfs) A unit used to measure water flow. One cubic foot per second is equal to 449 gallons per minute.
Culvert A buried pipe that allows flows to pass under a road.
Cut Off A channel cut across the neck of a bend, eliminating the bend.
D   top
Dead Stout Stakes Stakes made from 2- by 4-inch lumber used to hold erosion control fabric, fascines, and brush mattresses, and so on, in place.
Deadman A log, timber, block of concrete, or pipe buried in a stream bank that is used to anchor a revetment with cable or chain.
Debris Any material, organic or inorganic, floating or submerged, moved by a flowing stream.
Deciduous Trees and plants that shed their leaves at the end of the growing season.
Decomposer Any of various organisms (as many bacteria and fungi) that feed on and break down organic substances (such as dead plants and animals).
Decomposition The breakdown of matter by bacteria and fungi, changing the chemical makeup and physical appearance of materials.
Degradation (1) A progressive lowering of the channel bed due to scour. Degradation is an indicator that the stream's discharge and/or sediment load is changing. The opposite of aggradation.
(2) A decrease in value for a designated use.
Deposition The settlement of materials out of moving water and onto the channel bed, banks, and flood plains that occurs when the flowing water is unable to transport the sediment load.
Dike (1) (Engineering) An embankment to confine or control water, especially one built along the banks of a river to prevent overflow of lowlands; a levee.
(2) A low wall that can act as a barrier to prevent a spill from spreading.
Discharge The volume of water passing through a section of channel during a specified period of time, which is usually measured in cubic feet per second (cfs) or cubic meters per second (m3/sec).
Dissolved Oxygen (DO) The amount of free (not chemically combined) oxygen dissolved in water, wastewater, or other liquid, usually expressed in milligrams per liter, parts per million, or percent of saturation.
Ditch A long narrow trench or furrow dug in the ground, as for irrigation, drainage, or a boundary line.
Diversion The transfer of water from a stream, lake, aquifer, or other source of water by a canal, pipe, well, or other conduit to another watercourse or to the land, as in the case of an irrigation system.
Diversion Channel (1) An artificial channel constructed around a town or other point of high potential flood damages to divert floodwater from the main channel to minimize flood damages.
(2) A channel carrying water from a diversion dam.
Diversity The distribution and abundance of different plant and animal communities.
Drainage Area The total surface area upstream of a point on a stream that drains toward that point. Not to be confused with watershed. The drainage area may include one or more watersheds.
Drainage Basin The total area of land from which water drains into a specific river.
Dredging Removing material (usually sediments) from wetlands or waterways, usually to make them deeper or wider.
Drought Generally, the term is applied to periods of less than average or normal precipitation over a certain period of time sufficiently prolonged to cause a serious hydrological imbalance resulting in biological losses (impact flora and fauna ecosystems) and/or economic losses (affecting people). In a less precise sense, it can also signify nature's failure to fulfill the water wants and needs of people.
Dry Wash A stream bed that carries water only during and immediately following rainstorms.
Duckbill Anchor A short piece of steel tube, pointed at one end. A steel cable is attached to the tube halfway down its length. The duckbill is driven into the soil to the desired depth. Pulling up on the attached cable rotates the bill, making it somewhat parallel to the surface and setting the anchor.
Duff A spongy layer of decaying leaves, branches, and other organic materials covering the forest floor.
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Ecology The study of the interrelationships of living organisms to one another and to their surroundings.
Ecosystem An ecological community considered together with nonliving factors of its environment as an environmental unit.
Ecosystem Function (1) The process through which the constituent living and nonliving elements of ecosystems change and interact, including biogeochemical processes and succession.
(2) A role of an ecosystem that is of value to society.
Ecosystem Management A strategy or plan to manage ecosystems to provide for all associated organisms, as opposed to a strategy or plan for managing individual species.
Ecotone A relatively narrow overlap zone between two ecological communities.
Eddy A circular current of water, usually resulting from an obstruction.
Effluent (1) Something that flows out or forth, especially a stream flowing out of a body of water.
(2) (Water Quality) Discharged wastewater such as the treated wastes from municipal sewage plants, brine wastewater from desalting operations, and coolant waters from a nuclear power plant.
Embankment An artificial deposit of material that is raised above the natural surface of the land and used to contain, divert, or store water, support roads or railways, or for other similar purposes.
Energy Dissipation The loss of kinetic energy of moving water due to internal turbulence, bottom friction, large rocks, debris, or other obstacles that impede flow.
Enhancement Emphasis on improving the value of particular aspects of water and related land resources.
Environment The sum of all external influences and conditions affecting the life and development of an organism or ecological community; the total social and cultural conditions.
Environmental Analysis An analysis of alternative actions and their predictable short-term and long-term environmental effects, incorporating physical, biological, economic, and social considerations.
Environmental Assessment (EA) A systematic analysis of site-specific activities used to determine whether such activities have a significant effect on the quality of the human environment and whether a formal environmental impact statement is required; and to aid an agency's compliance with the National Environmental Policy Act when no environmental impact statement is necessary.
Environmental Impact The positive or negative effect of any action upon a given area or resource.
Environmental Impact Statement (EIS) A formal document to be filed with the U.S. Environmental Protection Agency that considers significant environmental impacts expected from implementation of a major federal action.
Ephemeral Streams Streams that flow only in direct response to precipitation and whose channel is at all times above the water table.
Erosion Wearing away of rock or soil by the gradual detachment of soil or rock fragments by water, wind, ice, and other mechanical, chemical, or biological forces.
Erosion Control Fabric (geotextile) Woven or spun material made from natural or synthetic fibers and placed to prevent surface erosion.
Estuary A coastal body of water that is semienclosed, openly connected with the ocean, and mixes with freshwater drainage from land.
Eutrophic Usually refers to a nutrient-enriched, highly productive body of water.
Eutrophication The process of enrichment of water bodies by nutrients.
Evaporation The physical process by which a liquid (or a solid) is transformed to the gaseous state. In hydrology, evaporation is vaporization that takes place at a temperature below the boiling point.
Evapotranspiration The processes by which plants take in water through their roots and then give it off through their leaves as a by-product of respiration.
F   top
Failure Collapse or slippage of a large mass of bank material into a stream.
FascineSee Live Fascine.
Fetch The open area and distance across a body of water in which wind can exert energy on waves to increase their strength of impact on the shoreline.
Fill (1) (Geology) Any sediment deposited by any agent such as water so as to fill or partly fill a channel, valley, sink, or other depression.
(2) (Engineering) Soil or other material placed as part of a construction activity.
Fines Silt and clay particles.
Fish Habitat The aquatic environment and the immediately surrounding terrestrial environment that meet the necessary biological and physical requirements of fish species during various life stages.
Flash Flood A sudden flood of great volume, usually caused by a heavy rain. Also, a flood that crests in a short length of time and is often characterized by high-velocity flows.
Flood plain Any lowland that borders a stream and is inundated periodically by its waters.
Flood Plain (100-year) The area adjacent to a stream that is on average inundated once a century.
Flow The amount of water passing a particular point in a stream or river, usually expressed in cubic feet per second (cfs).
Flow Augmentation Increased flow from release of water from storage dams.
Fluvial Migrating between main rivers and tributaries. Of or pertaining to streams or rivers.
Ford A shallow place in a body of water, such as a river, where one can cross by walking or riding on an animal or in a vehicle.
Fry A recently hatched fish.
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Gabion A wire basket or cage that is filled with gravel or cobble and generally used to stabilize stream banks.
Gaging Station A particular site in a stream, lake, reservoir, etc., where hydrologic data are obtained.
Gallons Per Minute (Gpm) A unit used to measure water flow.
Geomorphology The geologic study of the characteristics, origin, and development of landforms.
GeotextileSee Erosion Control Fabric
Goal The desired state or condition that a resource management policy or program is designed to achieve.
Grade The individual profile and pattern that a river has developed to efficiently move the discharge and sediment delivered to it.
Gradient Vertical drop per unit of horizontal distance.
Grass/Forb Herbaceous vegetation.
Gravel An unconsolidated natural accumulation of rounded rock fragments, mostly of particles larger than sand (diameter greater than 2 mm), such as boulders, cobbles, pebbles, granules, or any combination of these.
Gray Water Wastewater from a household or small commercial establishment that specifically excludes water from a toilet, kitchen sink, dishwasher, or water used for washing diapers.
Groundwater Subsurface water and underground streams that can be collected with wells or that flow naturally to the earth's surface through springs.
Groundwater Recharge Increases in groundwater storage by natural conditions or by human activity.
Groundwater Table The upper surface of the zone of saturation, except where the surface is formed by an impermeable body.
H   top
Habitat A place where a biological organism lives. The organic and nonorganic surroundings that provide life requirements such as food and shelter.
Habitat Conservation Plan (HCP) An agreement between the Secretary of the Interior and either a private entity or a state that specifies conservation measures that will be implemented in exchange for a permit that would allow taking of a threatened or endangered species.
Habitat Diversity The number of different types of habitat within a given area.
Habitat Fragmentation The breaking up of habitat into discrete islands through modification or conversion of habitat by management activities.
Hard Water Water high in multivalent cations, such as calcium and magnesium. This type of water does not lather easily when used with soap and forms a scale in containers when allowed to evaporate.
Hardpan A layer of nearly impermeable soil beneath a more permeable soil, formed by natural chemical cementing of the soil particles.
Hatch Box A device used to incubate relatively small numbers of fish eggs. The hatch box is usually located adjacent to a stream, which supplies the box with water.
Hazardous Materials Anything that poses a substantive present or potential hazard to human health or the environment when improperly treated, stored, transported, disposed of, or otherwise managed.
Headcut The development and upstream movement of a vertical or near-vertical change in bed slope, generally evident as falls or rapids. Headcuts are often an indication of major disturbances in a stream system or watershed (see also Nick Point).
Headwater Referring to the source of a stream or river.
Hydraulic Gradient The slope of the water surface (see also stream gradient).
Hydraulic Radius The cross-sectional area of a stream divided by the wetted perimeter.
Hydric Wet.
Hydrograph A curve showing stream discharge over time.
Hydrologic Balance An accounting of all water inflow to, water outflow from, and changes in water storage within a hydrologic unit over a specified period of time.
Hydrologic Region A study area, consisting of one or more planning subareas, that has a common hydrologic character.
Hydrology The study of the occurrence, circulation, properties, and distribution of water and its atmosphere.
Hyporheic Zone The area under the stream channel and flood plain where groundwater and the surface waters of the stream are exchanged freely.
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Incised Channel A stream that through degradation has cut its channel into the bed of the valley.
Incised River A river that erodes its channel by the process of degradation to a lower base level than existed previously or is consistent with the current hydrology.
Infiltration That portion of rainfall or surface runoff that moves downward into the subsurface rock and soil.
Inflow Water that flows into a stream, lake, reservoir, or forebay during a specified period.
Instream Flows (1) Portion of a flood flow that is contained by the channel.
(2) A minimum flow requirement to maintain ecological health in a stream.
Instream Use Use of water that does not require diversion from its natural watercourse. For example, the use of water for navigation, recreation, fish and wildlife, aesthetics, and scenic enjoyment.
Intermittent Stream A stream that has interrupted flow or does not flow continuously.
J   top
Joint Planting The insertion of live stakes in the spaces or joints, between previously placed rock riprap. When placed properly, the cuttings are capable of rooting and growing.
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Keyed In Refers to tying the ends of a structure into the bank to prevent water from going behind it.
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Lake An inland body of standing water deeper than a pond, an expanded part of a river, a reservoir behind a dam.
Landscape A heterogeneous land area with interacting ecosystems that are repeated in similar form throughout.
Landscape Diversity The size, shape, and connectivity of different ecosystems across a large area.
Landscape Features The land, water, vegetation, and structures that compose the characteristic landscape.
Landslide A movement of earth mass down a steep slope.
Large Woody Debris (LWD) Pieces of wood larger than 10 ft long and 6 inches in diameter in a stream channel.
Leaching The flushing of minerals or pollutants from the soil or other material by the percolation of applied water.
Leaf Area Index A measure of the total area of leaves, twigs, stems, etc., relative to the area of the canopy in a forest.
Levee An embankment constructed to prevent a river from overflowing (flooding).
Lifts Layers of loose soil wrapped in erosion control fabric used to rebuild and recontour a bank.
Limnology The study of life in lakes, ponds, and streams.
Littoral Shelf The sedimentary material on shorelines formed by waves and currents.
Littoral Transport The movement of sedimentary, either parallel (long-shore transport) or perpendicular (on-shore transport), to the shoreline.
Live Branch Cuttings Living, freshly cut branches from woody shrub and tree species that readily propagate when embedded in soil.
Live Cribwall A rectangular framework of logs or timber constructed with layers of live plant cuttings that are capable of rooting.
Live Fascine (fascines) Bound, elongated, cylindrical bundles (6 to 8 inches in diameter) of live branch cuttings used to stabilize stream banks that are placed in shallow trenches, partly covered with soil, and staked in place, also referred to as wattle.
Live Stake Live branch cuttings that are tamped or inserted into the earth to take root and produce vegetative growth.
Loading The influx of pollutants to a selected water body.
Lotic Meaning or regarding things in running water.
M   top
Macroinvertebrate Invertebrates visible to the naked eye, such as insect larvae and crayfish.
Macrophytes Aquatic plants that are large enough to be seen with the naked eye.
Main Stem The principal channel of a drainage system into which other smaller streams or rivers flow.
Mass Movement The downslope movement of earth caused by gravity. Includes but is not limited to landslides, rock falls, debris avalanches, and creep. It does not, however, include surface erosion by running water. It may be caused by natural erosional processes or by natural disturbances (e.g., earthquakes or fire events) or human disturbances (e.g., mining or road construction).
Mean Annual Discharge Daily mean discharge averaged over a period of years. Mean annual discharge generally fills a channel to about one-third of its bank full depth.
Mean Velocity The average cross-sectional velocity of water in a stream channel. Surface values typically are much higher than bottom velocities. May be approximated in the field by multiplying the surface velocity, as determined with a float, times 0.8.
Meander A circuitous winding or bend in the river.
Meander Amplitude The distance between points of maximum curvature of successive meanders of opposite phase in a direction normal to the general course of the meander belt, measured between center lines of channels.
Meander Belt Width The distance between lines drawn tangential to the extreme limits of fully developed meanders. Not to be confused with meander amplitude.
Meander Length The lineal distance downvalley between two corresponding points of successive meanders of the same phase.
Mesic Moderately wet.
Milligrams per Liter (Mg/L) The weight in milligrams of any substance dissolved in 1 liter of liquid; nearly the same as parts per million by weight.
Mineralization The process whereby concentrations of minerals, such as salts, increase in water, often a natural process resulting from water dissolving minerals found in rocks and soils through which it flows.
Morphology The form, shape, or structure of a stream or organism.
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National Pollutant Discharge Elimination System (NPDES) A provision of Section 402 of the Federal Clean Water Act of 1972 that established a permitting system for discharges of waste materials to watercourses.
Natural Flow The flow past a specified point on a natural stream that is unaffected by stream diversion, storage, import, export, return flow, or change in use caused by modifications in land use.
Nick Point The point where the stream is actively eroding the stream bed to a new base level. Nick points migrate upstream (see also Headcut).
Non-Point Source Pollution (NPS) Pollution that does not originate from a clear or discrete source.
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Off-Channel Area Any relatively calm portion of a stream outside of the main flow.
Off-Site Enhancement The improvement in conditions for fish or wildlife species away from the site or development activities that may have detrimental effects on fish and/or wildlife, as part or total compensation for those effects.
Outfall The mouth or outlet of a river, stream, lake, drain, or sewer.
Oxbow A loop or bend in the river that is cut off from the main channel.
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Pathogens Any viruses, bacteria, or fungi that cause disease.
Peat Partially decomposed plants and other organic material that build up in poorly drained wetland habitats.
Percolation The downward movement of water through the soil or alluvium to a groundwater table.
Perennial Stream A stream that flows continuously throughout the year.
Permeability The capability of soil or other geologic formations to transmit water.
Point Bar A gravel or sand deposit on the inside of a river bend; an actively mobile river feature.
Point Source (PS) Pollution Pollutants discharged from any identifiable point, including pipes, ditches, channels, sewers, tunnels, and containers of various types (see Non-Point Source (NPS) Pollution).
Pollutant (1) Something that pollutes, especially a waste material that contaminates air, soil, or water.
(2) Any solute or cause of change in physical, chemical, or biological properties that renders water unfit for a given use.
Pond A body of water smaller than a lake, often artificially formed.
Pool A reach of stream that is characterized by deep, low-velocity water and a smooth surface.
Pool/Riffle Ratio The ratio of surface area or length of pools to the surface area or length of riffles in a given stream reach; frequently expressed as the relative percentage of each category. Used to describe fish habitat rearing quality.
Proper Functioning Condition The functioning condition of riparian wetland areas is a result of interaction among geology, soil, water, and vegetation. Riparian wetland areas are functioning properly when adequate vegetation is present to dissipate stream energy associated with high-water flows, thereby reducing erosion and improving water quality; filter sediment and aid flood plain development; improve floodwater retention and groundwater recharge; develop root masses that stabilize stream banks against cutting action; develop diverse ponding and channel characteristics to provide the habitat and the water depth, duration, and temperature necessary for fish production, waterfowl breeding, and other uses; and support greater biodiversity.
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Rapids A reach of stream that is characterized by small falls and turbulent, high-velocity water.
Reach A section of stream between two defined points.
Rearing Habitat Areas in rivers or streams where juvenile fish find food and shelter to live and grow.
Rearing Pond An artificial impoundment in which juvenile fish are raised prior to release into the natural habitat.
Rebar Steel reinforcement bar used primarily for reinforcing concrete. It has a variety of uses in restoration work.
Recycled Water Urban wastewater that becomes suitable, as a result of treatment, for a specific direct beneficial use (see also Water Recycling).
Reforestation The natural or artificial restocking of an area with forest trees.
Reservoir Capacity The storage capacity available in a reservoir for all purposes, from the stream bed to the normal maximum operating level. Includes dead (or inactive) storage, but usually excludes surcharge (water temporarily stored above the elevation of the top of the spillway).
Restoration The return of an ecosystem to a close approximation of its condition prior to disturbance.
Revetment A facing of stone, wood, or other natural materials placed on a bank as protection against wave action and currents.
Riffle A reach of stream that is characterized by shallow, fast-moving water broken by the presence of rocks and boulders.
Rift A shallow or rocky place in a stream, forming either a ford or a rapid.
Rill Erosion Removal of soil particles from a bank slope by surface runoff moving through relatively small, narrow channels.
Riparian Located on the banks of a stream or other body of water.
Riparian Area An area of land and vegetation adjacent to a stream that has a direct effect on the stream. This includes woodlands, vegetation, and flood plains.
Riparian Habitat The aquatic and terrestrial habitat adjacent to streams, lakes, estuaries, or other waterways.
Riparian Vegetation Vegetation growing along banks of streams, rivers, and other water bodies tolerant to or more dependent on water than plants further upslope.
Ripple (1) A specific undulated bed form found in sand bed streams.
(2) Undulations or waves on the surface of flowing water.
Riprap A layer, facing, or protective mound of rubble or stones randomly placed to prevent erosion, scour, or sloughing of a structure or embankment; also, the stone used for this purpose.
River Channels Large natural or artificial open streams that continuously or periodically contain moving water or which form a connection between two bodies of water.
River Miles Generally, miles from the mouth of a river to a specific destination or, for upstream tributaries, from the confluence with the main river to a specific destination.
River Reach Any defined length of a river.
River Stage The elevation of the water surface at a specified station above some arbitrary zero datum (level).
Riverine Relating to, formed by, or resembling a river including tributaries, streams, brooks, etc.
Riverine Habitat The aquatic habitat within streams and rivers.
Root Wad A short length of tree trunk with a root mass.
Run The straight fast-moving section of a stream between riffles.
Runoff Water that flows over the ground and reaches a stream as a result of rainfall or snowmelt.
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Salinity The concentration of mineral salts dissolved in water. Salinity may be measured by weight (total dissolved solids), electrical conductivity, or osmotic pressure. Where seawater is known to be the major source of salt, salinity is often used to refer to the concentration of chlorides in the water.
Salmonids Fish of the family Salmonidae, including salmon, trout, char, whitefish, ciscoe, and grayling.
Sand Small substrate particles, generally from 0.06 to 2 mm in diameter. Sand is larger than silt and smaller than gravel.
Scour Concentrated erosive action of flowing water in streams that removes and carries away material from the bed and banks.
Secchi Depth A relatively crude measurement of the turbidity (cloudiness) of surface water. The depth at which a Secchi disc (disk), which is about 10-12 inches in diameter and with a black and white pattern, can no longer be seen.
Secchi Disc A circular plate, generally about 10-12 inches in diameter, used to measure the transparency or clarity of water by noting the greatest depth at which it can be visually detected. Its primary use is in the study of lakes.
Sediment Soil particles that have been transported and/or deposited by wind or water action.
Sediment Load The sediment transported through a channel by stream flow.
Sedimentation (1) The combined processes of soil erosion, entrainment, transport, deposition, and consolidation.
(2) Deposition of sediment.
Seepage The gradual movement of a fluid into, through, or from a porous medium.
Sewage The liquid waste from domestic, commercial, and industrial establishments.
Shear Strength The internal resistance of a body to shear stress. Typically includes frictional and cohesive components. Expresses the ability of soil to resist sliding.
Shear Stress The force per unit area tending to deform a material in the direction of flow. The pull on a bank that may cause it to slide.
Silt Slightly cohesive to noncohesive soil composed of particles that are finer than sand but coarser than clay; commonly in the range of 0.004 to 0.0625 mm, silt will crumble when rolled into a ball.
Siltation The deposition or accumulation of fine soil particles.
Sinuosity A measure of the amount of a river's meandering; the ratio of the river channel length to the valley length. A straight channel has a sinuosity of 1.0; a fully meandering river has a sinuosity of 2.0 or greater.
Slope The ratio of the change in elevation over distance.
Slope Stability The resistance of a natural or artificial slope or other inclined surface to failure by mass movement.
Slough An inlet or backwater, sometimes an alternate branch of a river.
Sloughing The downward slipping of a mass of soil, moving as a unit usually with backward rotation, down a bank. Also called sloughing off or slumping. Sloughing is similar to a landslide.
Snag Any standing dead, partially dead, or defective (cull) tree at least 10 inches in diameter at breast height and at least 6 ft tall. Snags are important riparian habitat features.
Soil Bioengineering (bioengineering) An applied science that combines structural, biological, and ecological concepts to construct living structures for erosion, sediment, and flood control. It is always based on sound engineering practices integrated with ecological principles.
Spawning The depositing and fertilizing of eggs (or roe) by fish and other aquatic life.
Spillway A channel for reservoir overflow.
Stable Channel A stream channel with the right balance of slope, planform, and cross section to transport both the water and sediment load without net long-term bed or bank sediment deposition or erosion throughout the stream segment.
Stone Rock or rock fragments used for construction.
Stream A general term for a body of water flowing by gravity; natural watercourse containing water at least part of the year. In hydrology, the term is generally applied to the water flowing in a natural narrow channel as distinct from a canal.
Stream Bank The side slopes of a channel between which the stream flow is normally confined.
Stream Bank Erosion The removal of soil from stream banks by flowing water.
Stream Bank Failure Collapse or slippage of a large mass of bank material into the channel caused by hydraulic or geotechnical modes or a combination of both.
Stream Bank Stabilization The lining of stream banks with riprap, matting, etc., or other measures intended to control erosion.
Stream Bed (1) The unvegetated portion of a channel boundary below the baseflow level.
(2) The channel through which a natural stream of water runs or used to run, as a dry stream bed.
Stream Channel A long, narrow depression shaped by the concentrated flow of a stream and covered continuously or periodically by water.
Stream Flow The movement of water through a channel.
Stream Flow The rate at which water passes a given point in a stream or river, usually expressed in cubic feet per second (cfs).
Stream Gradient A general slope or rate of change in vertical elevation per unit of horizontal distance of the bed, water surface, or energy grade of a stream.
Stream Morphology The form and structure of streams.
Stream Order A hydrologic system of stream classification. Each small unbranched tributary is a first-order stream. Two first-order streams join to make a second-order stream. A third-order stream has only first-and second-order tributaries, and so forth.
Stream Reach An individual segment of stream that has beginning and ending points defined by identifiable features such as where a tributary confluence changes the channel character or order.
Structure The spatial arrangement of the living and nonliving elements of an ecosystem.
Substrate (1) The composition of a stream bed, including either mineral or organic materials. (2) Material that forms an attachment medium for organisms.
Subsurface Drainage Rainfall that is not evapotranspirated or does not become surface runoff.
Surface Erosion The detachment and transport of soil particles by wind, water, or gravity or a group of processes whereby soil materials are removed by running water, waves and currents, moving ice, or wind.
Surface Runoff That portion of precipitation that moves over the ground toward a lower elevation and does not infiltrate the soil.
Surface Water All waters whose surface is naturally exposed to the atmosphere, for example, rivers, lakes, reservoirs, ponds, streams, impoundments, seas, estuaries, etc., and all springs, wells, or other collectors directly influenced by surface water.
Suspended Load The part of the total sediment load that is carried by the water for a considerable period of time at the velocity of the flow, free from contact with the stream bed (see also Bed load).
Suspended Sediment See Suspended Load
Sustainability The ability of an ecosystem to maintain ecological processes and functions, biological diversity, and productivity over time.
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Thalweg A line following the deepest part of the bed or channel of a stream.
Tied In An expression used to indicate that a technique is constructed to prevent stream flow between the structure and the bank (see Keyed In).
Toe The break in slope at the foot of a stream bank where it meets the stream bed.
Top of Bank The break in slope between the stream bank and the surrounding upland terrain.
Torrent (1) A turbulent, swift-flowing stream. (2) A heavy downpour; a deluge.
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Undercut Bank/Cut Bank The steep or overhanging slope on the outside of a meander curve, typically produced by lateral erosion of the stream. For all undercut banks, a protrusion of the upper portion of the bank overhangs the water surface at a flow equal to or less than bankfull.
Unstable Bank The stream bank shows evidence of active erosion, shearing, tension cracking, breakdown, and/or sloughing. Undercut banks are considered unstable if tension cracks show on the ground surface at the back of the undercut.
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Velocity (of water in a stream) The distance that water can travel in a specific direction during an interval of time. Usually expressed in feet per second (fps).
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Wash A dry stream bed. Usually found in the West.
Watershed An area of land surface defined by a topographic divide that collects precipitation into a stream. Sometimes referred to as a drainage basin.
Wattle See Live Fascine.
Wetland An area of land that is saturated at least a part of the year by water. Usually found in depressions, low-lying areas, or along flood plain or coastal areas.
Woody Debris Coarse wood material such as twigs, branches, logs, trees, and roots that fall into streams.
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