Glossary: Watershed Restoration Research Terms

Adaptive management

An iterative decision–making process involving a cycle of planning, implementing, monitoring, evaluating, and, subsequently, reexamining and altering management decisions based on monitoring results. 

Aggrade

Aggradation is a rise in grade or level of a stream–bed elevation through deposit of detritus, sediment. 

Alluvial groundwater (water table)

Water within the alluvium, or loose rock, gravel, soil, and sediment surrounding a channel.  This groundwater is linked hydrologically with water in the channel and strongly influences the channel, its riparian vegetation, and its connection with the floodplain.

Anastomosing channel

channel that branches and departs from the main channel, sometimes running parallel for several kilometers before rejoining the main channel.

Bankfull width

Channel width between the tops of banks on either side of a stream; tops of banks are the points at which water overflows its channel at bankfull discharge. Contrast wetted width.

Basal area

Square feet of total base area of trees (usual at breast height) per unit area (typically acre or hectare).

Baseline monitoring

Characterizing existing biota, chemical or physical conditions for planning or future comparisons.  Compare status, trend, implementation, effectiveness, and validation monitoring.

Basin

Entire land–drainage area of a river.  Also called watershed, drainage basin, or catchment.

Bed load

Sediment particles resting on the channel bottom that are pushed or rolled along by the flow of water.  Note that sediment can move between bed load and suspended load as the stream discharge changes.  Compare suspended load and wash load.

Benthic

Of, related to, or living in the soil–water interface of a lake or stream.

Biofilm

Community of microorganisms attached to a solid surface.

Bioswale

Vegetated channel commonly used to remove pollutants in storm water runoff.

Brush bundles

Groups of trees and branches placed into a lake or stream to create habitat and cover for fish.  Often used in conjunction with other habitat rehabilitation techniques.

Brush park

Submerged or partially submerged structures made of brush, branches, and aquatic vegetation secured in place with poles or fences.  They are designed to provide fish rearing areas, fishing opportunity, or refuge for fish.  They vary in size from a few square meters to several hectares and are used in lakes, streams, and brackish waters.

Bioturbation

Biological activities, such as burrowing and feeding in, at, or near the sediment surface, that occur and cause the sediment to become resuspended and mixed.

Blowdown

Trees uprooted and felled, or branches broken and felled by strong gusts of wind. Also called windthrow.

Catchment

Entire land–drainage area of a river.  Also called watershed, basin, or drainage basin.

Channel bifurcation ratio

Number of first–order channels divided by the number of second–order channels, the number of second order divided by third order, etc.  Bifurcation ratios provide insight into the maturity of tidal channel development.  Compare stream order.

Channelization

Straightening, narrowing, and deepening of a stream channel.  Channelization may be deliberate to improve navigation, move water faster, or prevent flooding of human infrastructure.  It often includes removal of debris and channel obstructions that may impede flow.

Channel unit

See habitat unit.

Coarse sediment

Generally, greater than 2–mm diameter, which is gravel, cobbles, or boulders.  Compare fine sediment.

Control site

A study location nearly identical to the treated location, with the exception that no treatment occurs.  See also reference site.

Coppicing

Forest regeneration from vegetative sprouts from stumps, branches, or roots.

Core area

For a species, part of its range that is typified by high and frequent use or that provides high–quality habitat for breeding, rearing, feeding, and other key functions necessary for survival.

Creation (habitat)

Construction of a new habitat or ecosystem where it did not previously exist.  This is often part of mitigation activities

Culvert

A transverse pipe or totally enclosed drain under a road or railway.  Typically used to convey stream flow under a road or other manmade construction.

Cross section

Profile of elevations perpendicular to the stream channel.

DBH (diameter at breast height)

A measurement of tree diameter taken at breast height.

Discing

Mechanical site–preparation technique used to break up soil and plow existing vegetation into the soil.  It usually is performed by towing a disc (a trailer on wheels with numerous sharp rotating discs that cut into the soil) behind a tractor.

Distributary

Branch of a river or a stream that flows away from the main channel and does not rejoin it.  Also called distributary channel.

Drainage basin

Entire land–drainage area of a river.  Also called watershed, basin, or catchment.

Easement

In restoration ecology, it refers to acquiring a portion of the rights to a land to allow for, or protect from, a specific use.  Technically defined as the nonpossessory interest granted in the lands of another, established to obtain certain limited rights granted in perpetuity or for set periods.  For example, development rights, but never the right to "quiet enjoyment."  Compare acquisition.

Ecoregion

Area determined by similar land–surface form, potential natural vegetation, land use, and soil; it may contain few or many geological districts.

Ecosystem

Dynamic and holistic system of all the living and dead organisms in an area and the physical and climatic features that are interrelated in the transfer of energy and material.

Effectiveness monitoring

Evaluating whether actions had the desired effects on physical processes, habitat, or biota.  Compare baseline, status, trend, implementation, and validation monitoring.

Endpoint

Composed of the variable, the sampling unit, and the statistic together.  Often used to establish a quantifiable measure of success. For example, a water–quality endpoint might be a mean daily maximum temperature of 16°C.

Enhancement

To improve the quality of a habitat through direct manipulation.  It does not necessarily seek to restore processes or conditions to some predisturbed state. Some practitioners call this partial restoration.  Compare rehabilitation and restoration.

Exclosure

Fencing an area to prevent (exclude) access of livestock or other ungulates.

Fine sediment

Generally, less than 2–mm diameter, typically composed of clay, silt, or sand. Compare coarse sediment.

Fining

Decrease in mean substrate particle size.

Floodplain

A flat depositional feature of a river valley adjoining the channel, the floodplain is formed by climate and hydrological conditions and is subject to periodic flooding.

Gabion

Wire rectangular or round basket placed in a stream channel and filled with gravel, gobbles, boulders or other hard material to serve as bank protection or to create a weir to trap gravel, create a pool, and improve fish habitat.

Girdling

Removing the layer of bark and cambium around the circumference of a tree, usually performed in an attempt to kill the tree.

Groin

A jetty extending from the bank into the channel designed to protect or stabilize a bank or trap gravel and sediment sands.

Glide

A shallow stream section (habitat unit or mesohabitat) with even laminar flow and little or no turbulence or obstructions.

Greenline

First perennial vegetation that forms a lineal grouping of community types on or near the water′s edge, most often at or below the bankfull stage.

Ground–truthing

Field measurement of specific attributes that have been predicted from models, maps, or remotely sensed data for the purpose of assessing accuracy and precision of predictions.

Gullying

Erosion of soil by formation or extension of channels (gullies) from surface runoff.

Habitat complexity

Determined by survey of physical structures such as large woody debris, sediment types, number and depth of pools, bars, etc. Complexity is a measures of habitat quality and has been correlated with survival and recruitment of fish.

Habitat unit

Distinct geomorphically defined area within a stream reach, such as a pool, a riffle, a glide, etc. Sometimes called a mesohabitat.

Hydraulic head

Water elevation and water pressure.

Hyporheic zone

The saturated interstitial areas below the streambed and into the streambanks (or floodplain), where stream water and deep groundwater intermix and where a number of important chemical, hydrological, and biological processes take place.

Implementation monitoring

Evaluating whether the restoration project was constructed (implemented) as planned. Compare baseline, status, trend, effectiveness, and validation monitoring.

Incised channel

An incised stream channel is one in which the stream bed is deepened to a point where flow is no longer connected the surrounding floodplain but cuts through the stream bed, resulting in further erosion and instability.  Incised channels are caused by erosion, usually resulting from an imbalance between sediment transport capacity and sediment supply to the stream. 

Large woody debris (LWD)

Large piece of woody material such as a log or stump that intrudes into or lies entirely within a stream channel; LWD typically is defined as wood greater than 10 cm in diameter and 1 m in length, but other minimum size criteria also are used.

Levee

An embankment or dike constructed of earth, rock or other material to prevent a river from overflowing.

LIDAR (light detection and ranging)

Using a principle similar to radar, the LIDAR instrument transmits light to a target and receives reflected or scattered light back for analysis. Change in the properties of light enable measurement of various properties of the target, such as distance, speed, rotation, or chemical composition and concentration.

Limiting factor

Factor that confines (limits) the growth of an ecosystem element.

Long profile (longitudinal profile)

Longitudinal plot of elevation versus distance (gradient), typically along the thalweg of a stream.

Main stem

Principal stream or channel of a stream network.

Mass wasting

Downslope movement of earth materials under gravity, including such processes as rockfalls, landslides, and debris flows.

Meiofauna

Benthic animals that can fit a mesh size of 1 mm and be retained on a mesh size of 42 Âμm.

Mesocosm

Surrogate for a real ecosystem that meets the requirement of being of sufficient size to contain all the components of interest while allowing "natural" behavior. In aquatic ecology, it often is an enclosed portion of a stream or other body of water or artificial stream channel, and may range from a few to several hundred square meters, depending on the ecosystem and organisms being studied.

Mesohabitat

Distinct geomorphically defined habitat area within a stream reach such as a pool, a riffle, a glide, etc.  Often called a habitat unit.

Metapopulation

Network of semi–isolated populations, with some level of regular or intermittent migration and gene flow among them, in which individual populations may go extinct but then the habitat they occupied can become recolonized from remaining populations.

Metric

Standard of measurement or combination of parameters used as a standard of measurement. See also parameter and variable.

Microhabitat

Specific locations where organisms live that contain combinations of habitat characteristics that directly influence the organism′s physiology or energetics in a small or restricted area.  In fisheries and aquatic ecology, this typically is at a scale smaller than a mesohabitat or a habitat unit and may include preferences for substrate, velocity, depth, etc.

Mitigation

Action taken to alleviate or compensate for potentially adverse effects on an aquatic habitat that has been modified or lost by human activity.

Monitoring

Systematically checking or scrutinizing something for the purpose of collecting specific categories of data, especially on a recurring basis. In ecology, it generally refers to systematically sampling something in an effort to detect or evaluate a change or lack of change in a physical, a chemical, or a biological parameter.  Compare baseline, status, trend, implementation, effectiveness, and validation monitoring.

Nutrient enrichment

Addition of organic or inorganic compounds to a water body to increase background levels of nutrients (e.g., phosphorous, nitrogen).

Overstory

Uppermost layer of foliage that forms a forest canopy. Compare understory.

Photic zone

Upper layers of bodies of water into which sunlight penetrates sufficiently to influence the growth of plants and animals.

Primary production

Creation of organic matter (biomass) by photosynthesis or chemosynthesis.

Primary productivity

Rate at which organic matter (biomass) produced by photosynthesis or chemosynthesis is stored in an ecological community or group of communities. Compare secondary productivity.

Rainsplash erosion

Transport of sediment by movement of water from precipitation, which typically causes soil particles to be splashed more on the downhill than on the uphill side of a slope.

Reach

A geomorphically similar stream section or a section of stream as defined by two selected points.

Reference site

Site in a relatively natural state, representative of conditions before human disturbance. See also control.

Reclamation

Returning an area to its previous habitat type but not necessarily fully restore all functions.

Redd

A spawning nest constructed in the substrate of a lake or stream by a fish.

Rehabilitation

To restore or improve some aspects or an ecosystem but not fully restore all components. A general restoration term that can include habitat improvement, enhancement, or reclamation. Some practitioners call this partial restoration. Compare enhancement and restoration.

Remote sensing

Gathering data from a remote station or platform, as in satellite or aerial photography.

Restoration

1. Return of an ecosystem to its predisturbed condition. Also called full restoration.

2. General term referring to various enhancement, improvement, and rehabilitation actions. 

Riffle

Shallow section of a river or stream, with moderate to rapid flow and with surface turbulence

Rill

One of the first and smallest channels formed by surface runoff.

Rilling

Removal of soil by water from small, well–defined, visible channels or streamlets where there is substantial overland flow.

Riparian

The banks of a river or the terrestrial aquatic interface. That part of a terrestrial landscape that exerts a direct influence on stream channels or lake margins, and the water or aquatic ecosystems.

Riprap

Layer of large, durable materials such as rock used to protect a streambank from erosion; also may refer to the materials used, such as rocks or broken concrete.

Rubble matt

The placement of rocks, boulders, or concrete into the stream channel to create diverse flow and velocities and create riffles or fast water habitats for fishes and other aquatic organisms.

Road prism

Road surface and fill, and its geometry. Road prism removal includes excavation of part or all of road fill to restore natural drainage patterns.

Samrah

See brush park.

Secondary productivity

Rate at which primary (plant and organism) material is synthesized into animal tissue per unit area in a given time period.  Compare primary productivity.

Sediment budget

Accounting of sediment sources and transfer processes in a watershed. The complete budget quantifies sediment sources, transport, and storage within a watershed, usually tracking each process of sediment production or movement separately.

Sediment supply

Supply of sediment to a river system, where it is carried in suspension (see suspended load and wash load) or on the bottom (see bed load).

Sheetwash

Surface erosion from water running off in sheets, distinct from channelized erosion in rills and gullies.

Side channel

a subsidiary or overflow channel branching from the primary stream channel, typically conveying a small fraction of the total stream flow.

Sill

A low weir partially buried in the stream bottom designed to aggrade or maintain the channel level and improve fish habitat.

Silviculture

In forestry or forest management, the care, cultivation, and harvest of trees. In restoration ecology, the term generally refers to planting, removing, or growing trees and other vegetation to restore certain forest characteristics.

Soil creep

Gradual downslope movement of the soil mantle.

Staking and layering (riparian planting)

A form of riparian replanting that involves both the vertical placement of live shoots or cuttings and the horizontal placement of larger cuttings or branches. Commonly used for establishing willows to stabilizing banks and soils.

Source–sink dynamics

Interplay between high–productivity (source) and low–productivity (sink) areas in which excess individuals produced in a source area help maintain populations in sink areas through immigration.

Status monitoring

Characterizing the condition (spatial variability) of physical or biological attributes across a given area. Compare baseline, trend, implementation, effectiveness, and validation monitoring.

Stream order

A method of classifying streams based on size and number of tributaries. Typically smallest streams are given smaller numbers. For example, a first–order stream would be the smallest detectable headwater stream, a second–order stream would be formed by the formation of two first–order streams, etc.

Succession

Changes in species composition of plants and animals in an ecosystem with time, often in a predictable order. More specifically, the gradual and natural progression of physical and biological changes, especially in the trophic structure of an ecosystem, toward a climax condition or stage.

Suspended load

Part of the total stream load that is carried for a considerable period of time in suspension, free from contact with the streambed; it mainly consists of clay, silt, and sand. Note that sediment can move between suspended load and bed load as the stream discharge changes. Compare bed load and wash load.

Terrace

Exposed former floodplain deposit that results when a stream begins downcutting into its floodplain. 

Thalweg

Line defining the lowest (deepest) points along the length of a stream.

Thinning

Removal of trees or other vegetation to allow for increased growth of other trees or vegetation.

Tidal prism

Volume of water between mean higher high water (MHHW) and mean lower low water (MLLW).

Trend monitoring

Monitoring changes in biota or physical conditions over time. Compare baseline, status, implementation, effectiveness, and validation monitoring.

Tributary

Stream or river that flows into another stream or river.

Understory

Shrubs and smaller trees between the ground cover and the forest canopy. Compare overstory.

Ungulate

Any of a number of hoofed, typically herbivorous, quadruped mammals, superficially similar but not necessarily closely related taxonomically.

UTM (Universal Transverse Mercator) Grid

Briefly, a grid base on the UTM geographic coordinate system.  The UTM represents locations in terms of northing and easting values.  Earth is divided into 60 numbered zones with each zone covering 6° longitude.  Easting values represent distance in meters from the longitudinal center of a numbered zone, while northing values represent distance in meters from the equator. For complete details, see U.S. Geological Survey Fact Sheet 077–01.

Validation monitoring

Evaluating whether the hypothesized cause–and–effect relationship between restoration action or other treatment, and physical and biological response were correct. Sometimes considered a part of effectiveness monitoring. Compare baseline, status, trend, implementation, and effectiveness monitoring.

Water bar

Construction of small (generally less than 50 cm) mound of soil and associated ditch across dirt or gravel roads to transport water across the road onto forest floor or adjacent hill slope. They are typically constructed on roads in mountainous areas to prevent water from running down the road surface and cause erosion. Variable attribute that may assume any one of a range of values. See also metric and parameter.

Voltinism

Number of life cycles repeated annually.

Wash load

Relatively fine material in near–permanent suspension that is transported entirely through the system without deposition. Compare bed load and suspended load.

Watershed

Entire land–drainage area of a river. Also called a basin, drainage basin, or catchment.

Weir

1. A low dam constructed in a stream to divert or retain water for various human uses.

2. A low dam or obstruction constructed of logs or rocks placed across a stream to create a pool or trap gravel and improve fish habitat.

Wetted width

Width of the water surface within a channel. Contrast bankfull width.

Windthrow

Trees uprooted and felled, or branches broken and felled by strong gusts of wind.  Also called blowdown.