Glossary of Environmental Terms Flashcards
Acid rain
Precipitation with pH levels much below average as a result of the formation of sulfuric acid in polluted air
Active layer
the surface layer in a permafrost environment, which is characterized by freezing and thawing on a seasonal basis
Aggradation
Filling in of a stream channel with sediment, usually associated with low discharges and/or heave sediment loads
Albedo
The percentage of incident radiation reflected by a material.
Alluvial fan
A fan-shaped deposit of sediment laid down by a stream at the foot of a slope; very common features in dry regions, where streams deposit their sediment load as they discharge downstream
Aquifer
Any subsurface material that holds a relatively large quantity of groundwater and is able to transmit that water readily
Backshore
The zone behind the shore – between the beach berm and the back shore slope
Backshore slope
The bank or bluff landward of the shore that is comprised of in situ material
Backswamps
A low, wet area in the floodplain, often located behind a levee
Bankfull discharge
The flow of a river when the water surface has reached bank level
Baseflow
The portion of streamflow contributed by groundwater; it is a steady flow that is slow to change even during rainless periods
Bay-mouth bar
A ribbon of sand deposited across the mouth of a bay
Berm
A low mount that forms along sandy beaches; also used to describe elongated mounds constructed along water features and site borders
Boreal forest
Subarctic conifer forests of North America and Eurasia; floristically homogeneous forests dominated by fir, spruce, and tamarack; in Russia, called taiga
Buildable land units
Parcels of various size within a designated project area that are suitable for development as defined by a prescribed development program
Carrying capacity
The level of development density or use an environment is able to support without suffering undesirable or irreversible degradation
Choropleth map
A map comprised of areas of any size or shape representing qualitative phenomena (e.g. soils) or quantitative phenomena (e.g. population); map often has a patchwork appearance
Climate
The representative or general conditions of the atmosphere at a place on earth; it is more than the average conditions of the atmosphere, for climate may also include extreme and infrequent conditions
Closed forest
A forest structure with multiple levels of growth from the ground up a forest in which undergrowth closes out the area between the canopy and the ground
Coastal dune
A sand dune that forms in coastal areas and is fed by sand from the beach
Colluvium
An unsorted mix of soil and mass-movement debris (accumulates at base of steep slope, for example after landslide)
Conduction
A mechanism of heat transfer involving no external motion or mass transport; instead, energy is transferred through the collision of vibrating molecules
Conveyance zone
The central route of drainage, usually a channel and valley, in drainage basin
Declination of the sun
The location (latitude) on earth where the sun on any day is directly overhead; declinations range from 23.27º S latitude to 23.27º N latitude
Degradation
Scouring and downcutting of a stream channel, usually associated with high discharges
Design storm
A rainstorm of a given intensity and frequency of recurrence used as the basis for sizing stormwater facilities such as storm sewers
Detention
A strategy used in stormwater management in which runoff is detained on site to be released later at some prescribed rate
Development density
A measure of the intensity of development or land use; defined on the basis of area covered by impervious surface, population density, or building floor area coverage, for example
Drainage basin
The area that contributes runoff to a stream, river, or lake
Drainage density
The number of miles (or km) of stream channels per square mile (or square kilometer) of land
Drainage divide
The border for drainage basin or watershed where overland separates between adjacent areas
Drainage network
A system of stream channels usually connected in a hierarchical fashion (see also principle of stream orders)
Drainfield
The network of pipes or tiles through which wastewater is dispersed into the soil
Ecosystem
A group of organisms linked together by a flow energy; also a community of organisms and their environment
Ecotone
The transition zone between two groups, or zones, of vegetation. The boundary of an ecosystem.
Environmental assessment
A preliminary study or review of a proposed action (project) and the influence it could have on the environment. Often conducted to determine the need for more detailed environmental impact analysis
Environmental impact statement
A study required by U.S. Federal law for projects (proposed) involving federal funds to determine types and magnitudes of impacts that would be expected in the natural and human environment and the alternative courses of action, including no action
Ephemeral stream
A stream without baseflow; one that flows only during and after rainstorms or snowmelt events
Environmental inventory
Compilation and classification of data and information on the natural and human features in an area proposed for some sort of planning project
Erodibility
The relative susceptibility of a soil to erosion
Erodibility factor
A value used in the universal soil loss equation for different soil type representing relative erodibility. Called the K-factor by the U.S. Soil Conservation Service
Erosion
The removal of rock debris by an agency such as moving water, wind, or glaciers; generally, the sculpting or wearing down of the land by erosional agents
Eutrophication
The increase of biomass of a waterbody leading to infilling of the basin and the eventual disappearance of open water; sometimes referred to as the aging process of a waterbody
Evapotranspiration
The loss of water from the soil through evaporation and transpiration
Feasibility study
A type of technical planning aimed at identifying the most appropriate use of a site
Fetch
The distance of open water in one direction across a water body; it is one of the main controls of wave size
Floodway fringe
The zone designated by U.S. Federal flood policy as the area in a river valley that would be lightly inundated by the 100-year flood
Frequency
The term used to express how often a specified event is equaled or exceeded
Frost wedging
A mechanical weathering process in which water freezes in a crack and exerts force on the rock, which may result in the breaking point of the rock; a very effective weathering process in alpine and polar environments
Geomorphic system
A physical system comprised of an assemblage of landform linked together by the flow of water, air, or ice
Geomorphology
The field of earth science that studies the origin and distribution of landforms, with special emphasis on the nature of erosional processes; traditionally, a field shared by geography and geology
Grafting
The practice of attaching additional channels to a drainage network; in agricultural areas new channels appear as drainage ditches; in urban areas, as stormsewers
Greenbelt
A tract of trees and associated vegetation in urbanized areas; it may be a park, nature preserve, or part of a transportation corridor
Gross sediment transport
The total quantity of sediment transported along a shoreline in some time period, usually a year
Ground frost
Frost that penetrates the ground in response to freezing surface temperatures
Ground sun angle
The angle formed between a beam of solar radiation and the surface that it strikes in the landscape
Groundwater
The mass of gravity water that occupies the subsoil and upper bedrock zone; the water occupying the zone of saturation below the soil water zone
Gullying
Soil erosion characterized by the formation of narrow steep-sided channels etched by rivulets or small streams of water. Gullying can by one of the the most serious forms of soil erosion of cropland
Habitat
The environment with which an organism interacts and from which it gains its resources; habitat is often variable in size, content, and location, chaining with the phases in an organism’s life cycle
Hardpan
A hardened soil layer characterized by the accumulation of colloids and ions
Hazard assessment
Study and evaluation of the hazard to land use and people from environmental threats such as floods, tornadoes, and earthquakes
Heat island
The area or patch of relatively warm air which develops over urbanized areas
Heat transfer
The flow of heat within a substance or the exchange of heat between substances by means of conduction, convection, or radiation
Hillslope processes
The geomorphic processes that erode and shape slopes; mainly mass movements such as soil creep and landslides and runoff processes such as rainwash and gullying
Hydrograph
A streamflow graph which shows the change in discharge over time, usually hours or days
Hydrograph method
A means of forecasting streamflow by constructing a hydrographic that shows the representative response of a drainage basin to a rainstorm; the use of a “normalized’ hydrographic for flow forecasting in which the size of the individual storm is filtered out
Hydrologic cycle
The planet’s water system, described by the movement of water from the oceans to the atmosphere to the continents and back to the sea
Hydrometer method
A technique used to measure the clay content in a soil sample that involves dispersing the clay particles in water and drawing off samples at prescribed time intervals
In situ
A term used to indicate that a substance is in place as contrasted with one, such as river sediment, that is in transit
Interception
The process by which vegetation intercepts rainfall or snow before it reaches the ground
Interflow
Infiltration water that moves laterally in the soil and seeps into stream channels; in forested areas this water is a major sources of stream discharge
Isopleth map
A map comprised of lines, called isolines, that connect points of equal value
Land cover
The materials such as vegetation and concrete that cover the ground
Landslide
A type of mass movement characterized by slippage of a body of material over a rupture plane; often a sudden and rapid movement
Land use
The human activities that characterize an area, e.g. agricultural, industrial, and residential
Latent heat
The heat released or absorbed when a substance changes phase as from liquid to gas. For water at 0ºC, heat is absorbed or released at a rate of 2.5 million joules per kilogram (597 calories per gram) in a liquid/vapor phase change
Leachate
Fluids that emanate from decomposing waste in a sanitary or chemical landfill
Levee
A mound of sediment that builds up along a river bank as a result of flood deposition
Line scanner
A remote sensing device that records signals of reflected radiation in scan lines that sweep perpendicular to the path (flight line) of the aircraft
Littoral drift
The material that is moved by waves and currents in coastal areas
Loess
Silt deposits laid down by wind over extensive areas of the midlatitudes during glacial and postglacial times
Mass movement
A type of hill slope process characterized by the downslope movement of rock debris under the force of gravity; it includes soil creep, rock fall, landslides, and mudflows; also termed mass wasting