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Instream Flows for Riverine Resource Stewardship
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Glossary
Abiotic - The nonliving material components of the environment such as water, sediment, and temperature.
Accretion - 1. Addition of flows to the total discharge of the stream channel, which may come from tributaries, springs, or seeps. 2. Increase of material such as silt, sand, gravel, water.
Adaptive management - A process whereby management decisions can be changed or adjusted based on additional biological, physical or socioeconomic information.
Aggradation - 1. Geologic process in which inorganic materials carried downstream are deposited in streambeds, floodplains, and other water bodies resulting in a rise in elevation in the bottom of the water body. 2. A state of channel disequilibrium, whereby the supply of sediment exceeds the transport capacity of the stream, resulting in deposition and storage of sediment in the active channel.
Allocation - See water allocation.
Alluvial stream - A stream with a bed and banks of unconsolidated sedimentary material subject to erosion, transportation, and deposition by the river.
Anadromous - Fish that mature in seawater but migrate to fresh water to spawn.
Annual flow - The total volume of water passing a given point in one year. Usually expressed as a volume (such as acre-feet) but may be expressed as an equivalent constant discharge over the year, such as cubic feet per second.
Appropriation - A specified amount of water set aside by Congress, other legislative body or state or provincial water regulatory authority to be used for a specified purpose at a specified place, if available.
Aquatic habitat - A specific type of area and its associated environmental (i.e.,
biological, chemical, or physical) characteristics used by an aquatic organism, population, or community.
Aquatic life - All organisms living in or on the water. This includes plants from the smallest phyroplankton through algae, pheriton, and emergent vegetation as well as animal life from zooplankton through benthic invertebrates, fishes, and amphibians, reptiles, birds, and mammals.
Aquifer - An underground formation that contains sufficient saturated permeable material to yield significant quantities of water to wells and springs.
Armoring - 1. The formation of an erosion-resistant layer of relatively large particles on the surface of a streambed or stream bank that results from removal of finer particles by erosion, and which resists degradation by water currents. 2. The application of materials to reduce erosion. 3. The process of continually winnowing away smaller substrate materials and leaving a veneer of larger ones.
Average daily flow - The long-term average annual flow divided by the number of days in the year usually expressed as an equivalent constant discharge such as cubic feet per second. In some settings, the value can be used to represent only the portion of the daily flow values in a defined period such as those that occur within a calendar month.
Average velocity - In a channel, it is equal to the discharge divided by the cross-sectional area of the cross section. For any point along the cross section, a measurement of 60% of the depth, measured from the surface, closely approximates the average velocity for the water column. In water greater than 76 cm (2.5 ft) deep, the average of measurements made at 20% and 80% of the depth approximates the mean column velocity.
For the remainder of the over 200 definitions order the book or borrow one from your local library.
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