Glossary of Watershed Terms

303 (d) Listed Water Body: A water body identified by the Region Water Quality Control Board to be impaired by one or more water quality constituents thus limiting the functioning of designated beneficial uses.
Abiotic: Something that is not living (for example, rock).
Aquatic Community: Any living thing (flora or fauna) living within or completely dependant on water for all or part of its life cycle..
Aquifer: A body of rock that can collect groundwater, and can yield water to wells and springs. A groundwater reservoir.
Biotic: Something that is living, or pertaining to living things.
Bluebelt: A term of art describing the land area directly adjacent to streams where water quality improvements are the primary objective in management efforts.
Brownbelt: A term of art describing recreational trails that can be closely associated with blue- and greenbelts.
Canopy Cover: The overhanging vegetation over a given area.
Channel Confinement: Ratio of bankfull channel width to width of modern floodplain. Modern floodplain is the flood-prone area and may correspond the 100-year floodplain. Typically, channel confinement is a description of how much a channel can move within its valley before it is stopped by a hill slope or terrace.
Channel Pattern: Description of how a stream channel looks as it flows down its valley (for example, braided channel or meandering channel).
Channelization: The process of structuralizing a natural stream channel, often with concrete, for flood protection purposes.
Cohesive: When describing soil, tendency of soil particles to stick together. Examples of soils with poor cohesion include soils from volcanic ash, and those high in sand or silt.
Coliform: A bacterial component used as an indicator of fecal contamination, which may lead to human health risks if exposed to contaminated waters.
Confluence: The location at which two streams intersect and begin to flow as one larger stream.
Connectivity: The physical connection between tributaries and the river, between surface water and groundwater, and between wetlands and these water sources.
Debris Flow: A type of landslide that is a mixture of soil, water, logs, and boulders that travel quickly down a steep channel.
De-synchronization: To interrupt the regular timing of a process. To hold stormwater temporarily within a surface water body or within wetland vegetation resulting in lower peak storm flows.
Discharge: Outflow; the flow of a stream, canal, or aquifer.
Disturbance: Events that can affect watersheds or stream channels, such as floods, fires, or landslides. They may vary in severity from small-scale to catastrophic, and can affect entire watersheds or only local areas.
Diurnal: Showing a periodic alteration of condition with day and night, such as the fluctuation of air temperature.
Downcutting: When a stream channel deepens over time.
Drainage Basin: A geographic and hydrologic subunit of a watershed.
Ecoregion: Land areas with fairly similar geology, flora, fauna, and landscape characteristics that reflect a certain ecosystem type.
Elevation: The vertical reference of a site location above mean sea level, measured in feet or meters.
Endemic Native species found only in a particluar geographic area with comparatively restricted habitat and distribution
Erodibility: The ease by which a soil may be eroded by natural forces or human disturbances.
Estuarine: Pertaining to, or in, an estuary.
Eutrophication: The process of increasing nutrient and decreasing oxygen supply within a water body. This process is detrimental, if not fatal, to aquatic wildlife.
Evapotranspiration (ET): The amount of water leaving to the atmosphere through both evaporation and transpiration.
Exotic Species: Plant or animal species brought into an area from another geographic region; see also Non-Native Species.
Feral: Non-domesticated animals living in a natural state or environment.
Flood Attenuation: When flood levels are lowered by water storage in wetlands.
Flood Peak: The highest amount of flow that occurs during a given flood event.
Floodplain: The flat area adjoining a river channel constructed by the river in the presence of climate, and overflowed at times of high river flow.
Gaging Station: A selected section of a stream channel equipped with a gage, recorder, or other facilities for measuring stream discharge.
Gaining Reach: Reach where groundwater is flowing into the stream channel to become surface water.
GIS: The combination of hardware and software used to store and analyze features located on the earth's surface.
Greenbelt: Usually referred to as an area around, or within, a city reserved by official authority for park land and open space. Stream corridors are often a key element linking various areas together.
Groundwater: Water that is beneath the surface of the ground, consisting mainly of surface water that has percolated down.
Headwaters: The small streams and upland areas that are the source of larger streams and rivers.
Hydraulic Gradient (hydraulic head): Water level from a given point upstream to a given point downstream; or the height of the water surface above a subsurface point. Used in analysis of both ground- and surface-water flow, and is an expression of the relative energy between two points.
Hydro-geomorphic: Pertaining to the influence of water on the formation of the earth's surface, and the influence of soil and geology on the flow of water.
Hydrograph: A graph of runoff rate, inflow rate, or discharge rate, past a specific point over time.
Hydrologic Cycle: The circulation of water around the earth, from ocean to atmosphere and back to ocean again.
Hydrology: The science of the behavior of water from the atmosphere into the soil.
Hydrophobic Soils: Soils that do not easily soak up water, and thus increase the rate of surface runoff.
Impervious Surface: Surface (such as pavement) that does not allow, or greatly decreases, the amount of infiltration of precipitation into the ground.
Infiltration Rate: The rate at which water penetrates the earth's surface.
Invasive Exotic: Plant or animal species from another geographic region that once introduced out compete native plants or animals and take over an habitat area.
Land Use: Typically a group of similar on-the-ground human uses described as a single category. (see Appendix B for a listing of Land Uses within the study area).
Large Woody Debris (LWD): Logs, stumps, or root wads in the stream channel, or nearby. These function to create pools and cover for fish, and to trop and sort stream gravels.
Low Flows: The minimum rate of flow for a given period of time.
Mass Wasting: (also soil mass movement): Downslope transport of soil and rocks due to gravitational stress.
Meandering: When a stream channel moves laterally across its valley.
Metabolize: The physical and chemical processes in an organism by which nutrients and other compounds are absorbed.
Non-Native Species: Plant or animal species brought into an area from another geographic region; see also Exotic Species.
Peak Flow: The maximum instantaneous rate of flow during a storm or other period of time.
Percolation: The act of surface water infiltrating into and through the ground.
Precipitation Intensity: The rate at which water is delivered to the earth's surface.
Precipitation: The liquid equivalent (inches) of rainfall, snow, sleet, or hail collected by storage gages.
Raindrop Splash: Erosion created when a raindrop hits a bare soil surface.
Raveling: Erosion caused by gravity, especially during rain and drying periods. Often seen on steep slopes immediately uphill of roads.
Recruited Large Woody Debris: A professional term assessing the amount or size of large trees in a riparian area that could potentially fall in (recruit) to the stream channel. Mechanisms for recruitment include small landslides, bank undercutting, wind throw during storms, individual trees dying of age or disease, and transport from upstream reaches.
Recurrence Interval (return interval): Determined from historical records. The average length of time between two events (rain, flooding) of the same size or larger. Recurrence intervals are associated with a probability. (For example, a 25-year flood would have a 4% probability of happening in any given year.)
Rilling (surface rillng): Erosion caused by water carrying off particles of surface soil.
Riparian Area: Areas bordering streams and rivers.
Riparian Vegetation: Vegetation growing on or near the banks of a stream or other body of water in soils that are wet during some portion of the growing season. Includes areas in and near wetlands, floodplains, and valley bottoms (from Meehan 1991).
Riparian Zone: An administratively defined distance from the water's edge that can include riparian plant communities and upland plant communities. Alternatively, an area surrounding a stream, in which ecosystem processes are within the influence of the stream processes.
San Diego Basin Plan: A regulatory Plan developed by the San Diego Regional Water Quality Control Board that indentifies the designated beneficial uses, water constituents, and regulatory framework active within the hydrographic basins in the San Diego Region.
Sedimentation: The deposition or accumulation of sediment.
Sediments, fine and coarse: Fragments of rock, soil, and organic material transported are deposited into streambeds by wind, water, or gravity.
Shrink-Swell: The amount of elasticity (percent clay) in a soil.
Soil Creep: When gravity moves the soil mantle downhill at rates too small to observe.
Solar Radiation: The heat transferred to the earth by the sun.
Stand-replacing Fire: A fire of enough severity, at a local level, to kill all the mature trees.
Stormwater: The surface water runoff resulting from precipitation falling within a watershed.
Stream Density (drainage density): Total length of natural stream channels in a given areas, expressed as units of stream channel per square unit of area.
Streamflow: The active flow of water within a stream, river, or creek. May also be used in terms of lowflow, baseflow, etc.
Substrate: Mineral or organic material that forms the beds of a stream.
Surface Runoff: Water that runs across the top of the land without infiltrating into the soil.
Surface water: Water that is flowing across or contained on the surface of the earth, such as in rivers, streams, creeks, lakes, and reservoirs.
Tidal Flushing: The act of seawater displacing fresh water within a lagoon or estuary.
Toxin: Any of a group of poisonous, usually unstable compounds generated by microorganisms, plants, or animals.
Transpiration: Loss of water to the atmosphere from living plants.
Tributary: A smaller river or stream that joins a larger one and contributes to its water flow.
Upland Vegetation: Vegetation typical for a given region, growing on drier upland soils. The same plant species may grow in both riparian and upland zones.
Velocity: The speed at which water is flowing in a river or stream. Usually given in terms of cubic feet per second.
Water Quality Constituent: Any of a number of components affecting the quality of water as identified by the State Water Resources Control Board.
Watershed: The region of land drained by a river, stream, or creek.
Weir: A small dam placed in a river or stream to control or gage the flow of water.

Source: Carlsbad Watershed Management Plan