The liquid and solid wastes from farming, including: runoff and leaching
of pesticides and fertilizers; erosion and dust from plowing; animal manure
and carcasses; crop residues, and debris.
Surface water leaving farm fields because of excessive precipitation, irrigation,
or snowmelt. Agricultural runoff is grouped into the category of nonpoint-source
pollution because the potential pollutants originate over large areas and
the point of entry into water bodies cannot be precisely identified.
The primary form of nitrogen applied in fertilizers. The ion NH4 derived from ammonia. Behaves in many respects like an alkali metal ion.
The conditions occurring before a particular hydrologic event. For example,
antecedent soil moisture conditions prior to a rainfall event will have an
influence on infiltration rates.
Living in the water.
Habitat with water. Includes areas that are permanently covered by water
and surrounding areas that are occasionally covered by water.
For water velocity: the slowing, modification, or diversion of the flow
of water as with detention and retention ponds. For water quality: the process
of diminishing contaminant concentrations in water due to filtration, biodegradation, dilution, sorption, volatilization, and other processes.
Rate at which the process slows down or concentration decrease.
A method of erosion control in which materials (usually rock revetment)
are placed along the banks of a river in order to prevent encroachment on
The prevention of channel migration through bank protection.
bankfull event (bankfull discharge)
A flow condition in which streamflow completely fills the steam channel
up to the top of the bank. In undisturbed watersheds, the discharge condition
occurs on average every 1.5 to 2 years and controls the shape and form of
Maximum amount of discharge (usually measured in cubic feet/second) that
a stream channel can carry without overflowing.
Water height at bankfull discharge.
That portion of stream discharge derived from groundwater.
Usually the streamflow volume that occurs during the fall or early winter, e.g., October-December, November-January.
Associated with the sea bottom.
benthic macro invertebrates
An animal lacking a backbone or internal skeleton which lives on or near the bottom of a body of water (for example, crayfish, mayflies, and nymphs).
Because they spend their entire life cycle in water, they are good indicators
of the health of that waterbody.
benthic organism (benthos)
A form of aquatic plant or animal life that is found on or near the bottom of a stream, lake or ocean.
An earthen mound used to direct the flow of runoff around or through a best
management practice (BMP).
best management practices (BMP)
A method that has been determined to be the most effective, practical means
of preventing or reducing pollution from non-point sources.
A measure of the variety of the Earth’s species, of the genetic differences
within species, and of the ecosystems that support those species.
A vegetated depression located on a site that is designed to collect, store
and infiltrate runoff. Typically includes a mix of amended soils and vegetation.
Land adjoining and immediately adjacent to a stream that provides protection
from or filters unwanted constituents.
The process by which atmospheric carbon is absorbed in to carbon sinks such
as the oceans, forests and soil.
A structure in which water is collected; watershed basin.
Any compound containing a chlorine atom; any salt of hydrochloric acid (containing the chloride ion).
Habitats above spring high tide limit (or above mean water level in non-tidal
waters) occupying coastal features. Characterized by their proximity to the
sea, including coastal dunes and wooded coastal dunes, beaches and cliffs.
Includes free-draining supralittoral habitats adjacent to marine habitats which are normally only affected by spray or splash, strandlines characterized by terrestrial invertebrates and moist and wet coastal dune slacks and dune-slack pools. Excludes supralittoral rock pools and habitats adjacent to the sea which are not characterized by salt spray, wave or sea-ice erosion.
Lands and waters adjacent to the coast that exert an influence on the uses
of the sea and its ecology, or, inversely, whose uses and ecology are affected
by the sea.
The organized management and planned use of living and non-living natural
resources. “Water conservation” refers to strategies that increase the efficiency of water use, reuse, recycling, production, or distribution, or that decrease demand.
The measure of the quantity of contaminants (polluting substances) discharged
to the environment. The amount of contaminant being carried at a given time.
Specific area that contributes a certain amount of matter.
An important tool in quantifying pollution loads at specific time intervals during storm events, and for calculating phosphorus loads. The “minimum active contributing area” is a percentage of the total catchment area, in accord with the variable source area concept of storm runoff production.
In soil erosion processes, sediment transport models show that detachment
by shear forces occurs mainly in areas where water is concentrated (e.g.,
rills) rather than over a broad areas. Re-entrainment of sediments will take
place mainly from the base of the rill. Sources of stream sediments do not
necessarily coincide with major soil erosion areas because of the differences
in capacity of different parts of a watershed to transport sediments. A source
with a high soil erodibility located far from established channels may not
contribute as much pollution to a stream as a less erodible source near stream.
The area of a stream, channel, or waterway opening, usually taken perpendicular to the stream centerline.
The basis for much of our understanding of ground water flow in the subsurface environment. Darcy developed the law in the mid-19th century based on a series of experiments in France to understand water filtration.
detention pond (detention basin)
A structure designed to temporarily store stormwater in order to reduce the potential for flooding.
digital elevation model
An array of uniformly spaced elevation data.
The volume of water or a watery solution flowing past a point per unit time.
Common units are cubic feet per second or cubic meters per second.
dissolved oxygen (DO)
Concentration of oxygen, expressed in milligrams per liter, dissolved in water and readily available to fish and other aquatic organisms. Strongly influenced by temperature, biologic activity, biochemical oxygen demand, and chemical oxygen demand.
Fluctuations that occur during each day.
In the same direction as a stream or other flow, or toward the direction in which the flow is moving.
The land area drained by a river and its tributaries. Also called catchment, drainage area, river basin, or watershed.
The system of pipes, channels or watercourses to divert excess of water
from some area (agricultural fields, mines, urban areas, etc.).
The community of plants and animals within a water or terrestrial habitat
interacting together and with their physical and chemical environment.
Fill material, usually earth or rock, placed with sloping sides and usually with length greater than height. All dams are types of embankments.
Rising above a surrounding medium, especially a fluid.
A plant rooted in shallow water with much of the stem and most of the leaves
The susceptibility of a soil to erosion.
The wearing away of the land surface by wind or water. Erosion occurs naturally from weather or runoff but can be intensified by land-clearing practices related to farming, residential or industrial development, road building, or timber cutting.
Enrichment of an aquatic ecosystem with nutrients (nitrogen, phosphorus) that accelerate biological productivity (growth of algae and weeds) and an undesirable accumulation of algal biomass.
The process by which lakes and streams become enriched, to varying degrees, by concentrations of nutrients such as nitrogen and phosphorus. Enrichment results in increased plant growth (principal algae) and decay, the latter of which reduces the dissolved oxygen content. Highly eutrophic conditions may be considered undesirable, depending on the human use of the waterbody.
The process by which water is lost from the earth’s surface (evaporation) and from the leaves and stems of plants (transpiration).
A general term that typically describes an organism or species that is not native to the area in which it is found (i.e. it is non-indigenous). Exotic species may be invasive.
An estimate of the expected annual amount of a nutrient or water transported
from a unit of land to a receptor. Expressed in terms of mass per area per
unit of time.
Belts of vegetation (grass, shrubs, and/or trees) maintained along streams
or on the contours insloping fields to trap sediment and agricultural chemicals
before they enter waterways.
Act or technique of trying to control rivers with dams to minimize occurrence
of floods. The specific regulations and practices that reduce or prevent
the damage caused by stormwater runoff.
The low-lying land adjoining a river that is sometimes flooded; generally
covered by fine-grained sediments (silt and clay) deposited by the river
at flood stage.
An underground route for groundwater movement, extending from a recharge
(intake) zone to a discharge (output) zone such as a shallow stream.
The amount of flow per unit time (i.e. energy flux or radiation flux). The rate of flow of any quantity, usually a form of energy, through a unit area of specified surface.
An extra storage space provided near an inlet of a BMP to trap incoming
sediments before they accumulate in a pond BMP.
Wire basket, filled with stones, used to stabilize banks of a water course and to enhance habitat.
geographic information systems
A computer system for capturing, storing, querying, analyzing, and displaying geographically referenced data.
Undeveloped land usually in cities, set aside or used for recreation or
Water stored under the surface of the earth. It comes in the vast majority of cases from precipitation that falls on the earth’s surface. Some of the precipitation washes away immediately into lakes, rivers, and other water reservoirs, but most of the precipitation sinks into the soil, where it may become groundwater.
The pollution of springs and wells from their sources underground. It can
result from indiscriminate land disposal of potentially hazardous waste materials that are then dissolved or suspended in free liquids, usually water, and leach downward through the unsaturated profile to the zone of saturation
or from improperly constructed or operated wells.
Inflow of water to a groundwater reservoir from the surface. Infiltration of precipitation and its movement to the water table is one form of natural recharge. Also, the volume of water added by this process.
The period from the average date of the last frost (in the United States, this occurs in the spring) to the first frost in the fall.
The environment in which a plant or animal grows or lives; the surroundings
include physical factors such as temperature, moisture, and light, together
with biological factors such as the presence of food and predators.
The source or upper reaches of a stream; also the upper reaches of a reservoir.
With the characteristics of a herb; describes a plant with no persistent woody stem above ground.
A group of chemicals used to kill or reduce the growth of vegetation that is considered undesirable.
A part of a hill between its crest and the drainage line at the foot of the hill.
The hydrologic process taking place on hillslopes. Intrinsically related to stream flow generation.
Precipitation that flows off hillsides and appears in surface streams.
The ability of the soil to transmit water. Also commonly known as the permeability.
Darcy found that to relate the flow rate to the hydraulic head and area
of flow required a constant of proportionality (termed k) as the hydraulic
conductivity. It has units of velocity. Note that the value is a function
of both the porous media and the fluid.
The rate of change in which the head (or energy) is lost as water flows
through porous materials. Defined in algebraic form as: i= (h1-h2)/L where
h1: head at location 1 (cm), h2: head at location 2 (cm), and L: length of
sand column (cm).
The change in hydraulic head between two points (e.g., the difference in
water level between two points divided by the distance between the two points). In an aquifer, the rate of change of total head per unit of distance of flow at a given point and in a given direction. In a stream, the slope of the
hydraulic grade line.
The height of the free surface of a body of water above a given subsurface
The water level at a point upstream from a given point downstream.
The elevation of the hydraulic grade line at a given point of a pressure
Ratio of the cross-sectional area of the flow at a point in an open channel
or closed conduit to the wetted perimeter (R = A/P).
A soil that is saturated, flooded, or ponded long enough during the growing
season to develop anaerobic (oxygen-lacking) conditions that favor the growth
and regeneration of hydrophytic vegetation.
A graphical representation or plot of changes in the flow of water or changes
in the elevation of water level plotted against time.
The hydrologic cycle begins with precipitation that lands on the earth’s surface and can be in the form of rain, snow, etc. From there, the water may spread along the ground surface as surface water runoff or overland flow or may seep into the ground and become ground water. Overland flow may continue to concentrate as channel flow, and progressing as stream flow, continuing to concentrate in the form of streams and rivers until ultimately reaching the ocean. Infiltration causes surface water to change into groundwater.
hydrologic soil group
SCS classification system of soils based on the permeability and infiltration rates of the soils. “A” type soils are primarily sandy in nature with a high permeability while “D” type soils are primarily clayey in nature with a low permeability. Other groups include “B” and “C” types.”
The volume of sediment and porous space adjacent to a stream, and through
which stream water exchanges.
A condition in which natural waters have a low concentration of dissolved
oxygen (about 2 milligrams per liter as compared with a normal level of 8
to 10 milligrams per liter). Most game and commercial species of fish avoid
such waters. Compare with anoxia, which is less than 0.1 milliliter of oxygen
per liter, and the threshold below which animal life diminishes significantly.
A hard surface area that either prevents or retards the entry of water into
the soil mantle as under natural conditions prior to development. A hard
surface area that causes water to run off the surface in greater quantities
or at an increased rate of flow from the flow present under natural conditions
prior to development. Common impervious surfaces include, but are not limited
to, rooftops, walkways, patios, driveways, parking lots, storage areas, concrete
or asphalt paving, gravel roads, packed earthen materials, and oiled, macadam, or other surfaces that similarly impede the natural infiltration of urban runoff. Open, uncovered retention/detention facilities shall not be considered as impervious surfaces.
A depression scratched or carved into a surface.
The process by which water enters the soil and that is controlled by the character of the soil and surface conditions, such as slope and amount of
A stream that flows only periodically throughout the year.
Coastal land that is covered by water at high tide and uncovered at low
A plant or animal that moves in and takes over an ecosystem to the detriment
of other species; often the result of environmental manipulation.
A (bio)physical description of the earth’s surface. It is that which overlays or currently covers the ground. This description enables various biophysical categories to be distinguished – basically, areas of vegetation (trees, bushes, fields, lawns), bare soil, hard surfaces (rocks, buildings) and wet areas and bodies of water (watercourses, wetlands).
The process of managing the use and development of land resources. Land
resources are used for a variety of purposes which interact and may compete
with one another; therefore, it is desirable to plan and manage all uses
in an integrated manner.
Operations for preparing and controlling the implementation of plans for
organizing human activities on land.
The way land is developed and used in terms of the types of activities allowed
(agriculture, residences, industries, etc.) and the size of buildings and
structures permitted. Certain types of pollution problems are often associated
with particular land uses, such as sedimentation from construction activities.
The traits, patterns, and structure of a specific geographic area, including its biological composition, its physical environment, and its anthropogenic or social patterns. An area where interacting ecosystems are grouped and
repeated in similar form.
A generic term for a wide range of legislative and regulatory activities
intended to limit or direct land development for the purpose of making its
usage sustainable. Large-scale land-use plans often are implemented by local
zoning and land-use ordinances.
Liquid that has moved through a substance, removing solids from the substance, generally by dissolution.
Downward movement of a soluble material through the soil as a result of
water movement. The process by which soluble constituents are dissolved and
filtered through the soil by a percolating fluid.
Amount of a substance entering the environment (soil, water, or air).
Any nonvertebrate organism that is large enough to be seen without the aid of a microscope.
Manning’s roughness coefficient
Indicative of the resistance to the flow. Used in formula to compute the velocity of uniform flow in a open channel: V= 1.486/ n R(2/3) S (1/2), where V is the mean velocity of flow (in cfs units), R is the hydraulic radius in feet, S is the slope of the channel or sine of the slope angle, and n is the Manning roughness coefficient.
A type of wetland that does not accumulate appreciable peat deposits and
is dominated by herbaceous vegetation. Marshes may be either fresh or saltwater, tidal or non-tidal.
A microscopic organism. The term encompasses viruses, bacteria, yeast, molds, protozoa, and small algae.
Actions designed to lessen or reduce adverse impacts. Frequently used in
the context of environmental assessment.
Endemic, i.e. confound to certain area, or originated where it was located.
An element essential to the growth and development of plants. Occurs in manure and chemical fertilizer and, in excess, can cause waters to become polluted by promoting excessive growth of algae and other aquatic plants.
non-point source pollution
In general, sources of pollutants entering lakes, rivers, oceans, and other
waterways can be classified as point or nonpoint sources. A nonpoint source
is a extended area from which water flows, usually on an irregular basis.
Examples of nonpoint sources include agricultural land, developed land, forests, or landfills.
The difference between nutrient inputs and outputs. When the nutrient balance
is close to zero, nutrients applied in manure and fertilizer are closely matched to crop utilization. When the nutrient balance is positive, nutrient inputs exceed outputs. When the nutrient balance is negative, nutrient outputs exceed inputs.
Pathway of a nutrient through an ecosystem from assimilation (transformation
into living tissue) by organisms to release by decomposition. The cyclic
conversions of nutrients from one form to another within the biological communities.
Quantity of nutrients entering an ecosystem in a given period of time. The
nutrient load refers to the total amount of nitrogen or phosphorus entering
the water during a given time, such as “tons of nitrogen per year”.
A group of chemical elements or compounds needed for all plant and animal
life. Nitrogen and phosphorus are primary nutrients in aquatic systems. Excessive or imbalanced nutrients in water may cause problems such as accelerated eutrophication.
A law or rule enacted by an authority, such as a city government.
The flow of water over a land surface due to direct precipitation. Generally occurs when the precipitation rate exceeds the infiltration capacity of the soil.
The migration of water through the active soil profile into greater depths
where it may become groundwater.
The rate, usually expressed as a velocity, at which water moves through
saturated granular material. Also applies to quantity per unit of time of
A stream that flows throughout the year. During low-flow periods, the flow
of perennial streams is baseflow. Perennial streams are typical of humid
and subhumid climates, where groundwater reservoirs are subject to substantial wet-season recharge, discharging during dry season.
The maximum quantity of water that can be withdrawn annually from a ground
water supply under a given set of conditions without causing an undesirable
A broad group of chemicals that kills or controls plants (herbicides), fungus
(fungicides), insects and arachnids (insecticides), rodents (rodenticides),
bacteria (bactericides), or other creatures that are considered pests.
An element essential to the growth and development of plants. Occurs in manure and chemical fertilizer and, in excess, can cause waters to become polluted by promoting excessive growth of algae and other aquatic plants.
The upper water layers from the water surface and extending down to the
depth of effective light penetration where photosynthesis balances respiration.
This level (the compensation level) usually occurs at the depth of 1 percent
light penetration (for example, 1 percent of surface light intensity) and
forms the lower boundary of the zone of net metabolic production.
The process by which plants manufacture food from sunlight. Specifically,
the conversion of water and carbon dioxide to complex sugars in plant tissues
by the action of chlorophyll driven by solar energy.
A plant that habitually obtains its water supply from saturated zone, either
directly or through the capillary fringe.
The uptake of a chemical into plants is expressed in terms of a bioconcentration factor for vegetation, which is the ratio of the concentration in the plant tissue to the concentration in soil.
A chart or map showing the movements or progress of an object.
point source pollution
In general, sources of pollutants entering lakes, rivers, oceans, and other
waterways can be classified as point or nonpoint sources. Point sources are
municipal or industrial sites that can be specifically identified as the source from which pollutants are released into a waterway. Such sources might
include pipes or canals that flow from a municipal sewage system or industrial
plant into a waterway.
A contaminant in a concentration or amount that adversely alters the physical,
chemical, or biological properties of the natural environment.
The amount of pollutants entering a waterbody. Loads are usually expressed
in terms of a weight and a time frame, such as pounds per day (lb/d).
The number per unit area of individuals of any given species, including
humans, at a given time.
Forms in which liquid or solid water fall to the earth from the atmosphere.
The most common forms of precipitation are rain, sleet, glaze, snow, mist,
drizzle, hail, rime, and graupel. Dew and white frost are sometimes considered
forms of precipitation.
Means of computing peak storm drainage flow rates based on average percent
imperviousness of the site, mean rainfall intensity, and drainage area.
In hydraulics, the expression of peak discharge (in cfs units) as equal to rainfall (in inches/hr) times drainage area (in acres) times a runoff coefficient depending on drainage basin characteristics.
The Rational Method has served as the basis for United States storm drain
design practice since the turn of the 20th century. It is essentially a peak
discharge method based on the following formula: Q = kCiA ; where Q is the
peak flow rate in m3/s for return interval T years, C is the runoff coefficient
dependent on land use, i is the design rainfall intensity in cm per hour
for return period of T years and duration equal to the time of concentration
for the basin, A is the drainage area in hectares, and k =0.0278, the number
of m3/s in one hectare-cm/hour.
A segment of a stream channel.
recession limb of hydrograph (falling limb)
That portion of a hydrograph that shows the rate of decrease of stage or
discharge following passage of a crest; the opposite of rising limb.
Flow is regulated when it is managed to achieve various goals, such as maintaining a minimum flow downstream of a reservoir or maintaining a minimum depth for shipping.
The average time an element spends in a given environment between the time
it arrived and the time it is removed by some process. In the ocean, residence
time is defined as the concentration in sea water relative to the amount delivered to the ocean per year; in groundwater, it is the time elapsed between water being recharged to the aquifer; in lakes and reservoirs, it is the
time elapsed between a parcel of water entering the waterbody and leaving it.
The bank of a river or stream, or the shoreline of a lake or pond.
Vegetated areas next to water resources that protect water resources from
nonpoint source pollution and provide bank stabilization and aquatic and
A concept of water law under which authorization to use water in a stream is based on ownership of the land adjacent to the stream.
rising limb of hydrograph
The rising portion of the hydrograph resulting from runoff of rainfall or snowmelt.
Rosgen stream classification
A stream classification system developed by Dave Rosgen that groups stream
types based on certain geomorphological characteristics (e.g., channel slope,
shape, and materials). Useful in predicting a stream’s hydraulic and sediment
transport behavior under various conditions and in the application of natural
channel design methods in stream restoration work.
A factor in velocity and discharge formulas representing the effect of channel
roughness on energy losses in flowing water. Manning’s “n” is a commonly used roughness coefficient.
Includes many factors such as type of cover, soil types, infiltration, evaporation,
evapotranspiration, and any moisture condition. The fraction of total rainfall
that appears as runoff. Represented as “C” in the rational method formula.
Safe Drinking Water Act (SDWA)
Originally passed in 1974 to ensure that public water supplies are maintained at high quality. Amendments passed in 1986 require the EPA to set national
primary drinking water standards.
“Wet” conditions when media (i.e. watershed basin, soil layer, aquifer, etc.) are fully saturated with water and no infiltration takes place.
A condition in which the interstices of a material are filled with a liquid, usually water. It applies whether the liquid is under greater then or less than atmospheric pressure, as long as all connected interstices are full.
That part of the water-bearing material in which all voids, large and small, are ideally filled with water under pressure greater than atmospheric.
Soil Conservation Service (SCS)
Now called Natural Resource Conservation Service (NRCS), a branch of the
US Department of Agriculture.
Solid material, such as sand and clay, carried off the land by running water and later deposited in a river, lake, or other waterway. When rainwater runs off the land, it usually carries soil with it on its way to a river or lake.
Practices used on building sites to prevent sand, soil, cement and other
building materials from reaching waterways. Even a small amount of pollution
from a site can cause significant environmental damage by killing aquatic
life, silting up streams and blocking stormwater pipes.
The distance between a property boundary and a building. A minimum setback
is usually required by law.
A condition of flooding where there is moving water but no identifiable channel. Flooding depths are usually shallow (less than 3 feet). May have a high velocity, as on alluvial fans.
The branch of forestry dealing with the development and care of forests.
A substance or process that removes a component of concern from the active
environment. For example, the adsorption of metals on the surfaces of organic
matter serves as a sink for these elements as it removes them from a solution.
Degree of deviation of a surface from the horizontal, measured as a numerical
ratio, as a percent, or in degrees. Expressed as a ratio, the first number
is the horizontal distance (run) and the second number is the vertical distance
(rise), as 2:1. A 2:1 slope is a 50 percent slope. Expressed in degrees,
the slope is the angle from the horizontal plane, with a 90 degree slope
being vertical (maximum) and a 45 degree slope being a 1:1 slope.
A mixture of different inorganic and organic materials. The inorganic fraction
consists mostly of fine mineral grains. The percentages by weight of gravel,
sand, silt, and clay provide a basis for classifying soil by texture.
The removal of soil by wind or water.
Water in the soil mantle, available for use by plants.
Describes the characteristics of a given area. For example, the spatial distribution of whales in the ocean or the spatial distribution of aquifer thickness.
Any information about the location, shape of, and relationships among geographic features. This includes remotely sensed data as well as map data.
Variation (change) of a certain parameter within studied area.
A measure of the ability of water to conduct an electrical current, expressed
in micromhos per centimeter at 25 degrees Celsius. Related to the type and
concentration of ions in solution and can be used for approximating the dissolved-solids content of the water. Commonly, the concentration of dissolved solids (in milligrams per liter) is about 65% of the specific conductance (in micromhos). This relation is not constant from supply to supply, and it may even vary in the same source with changes in the composition of the water.
With reference to the movement of water in soil, a factor expressing the volume of transported water per unit of time in a given area.
The elevation of a water surface in relation to a datum.
A rainfall event that produces more than 0.1 inch of precipitation and that
which is separated from the previous storm event by at least 72 hours of
storm sewer system
System of pipes and channels that carry stormwater runoff from the surfaces
of building, paved surfaces, and the land to discharge areas.
The bed where a natural stream of water runs or may run. The long, narrow
depression shaped by the concentrated flow of a stream and covered continuously or periodically by water.
A method of flood control in which a river or stream channel is widened,
deepened, cleared, strengthened, and/or made more straight.
The flow in natural streams.
The replacement of one plant community by another over time.
A combination of sulfur in the oxidized state (S6+) and oxygen, and a part of naturally occurring minerals in some soil and rock formations. A common constituent in groundwater and surface water. Sulfate minerals tend to be
Water that runs across the top of the land without infiltrating the soil.
All the waters flowing on the surface of the earth, either by overland sheet
flow or by channel flow in rills, gullies, streams, or rivers.
Very fine soil particles that remain in suspension in water for a considerable
period of time without contact with the bottom. Such material remains in
suspension due to the upward components of turbulence and currents and/or
suspended sediment load
Suspended sediment concentration in a given volume of water.
Wetlands covered with water for most or all of the year and characterized
primarily by the presence of woody plants. Swamps often occurs close to adjacent rivers, streams, lakes, and other bodies water.
Variation (change) of a certain parameter within specified time interval.
A tract or region of the Earth’s surface considered as a physical feature, an ecologic environment, or a site of some planned human activity, e.g., an engineering location; or in terms of military science, as in terrain analysis.
Relationship between elevation and horizontal distance for a given length
of the terrain.
The shape and contour of a surface, especially the land surface or ocean-floor
surface, usually characterized by slope, aspect and elevation.
total dissolved nitrogen
The dissolved nitrogen in the water column.
total maximum daily loads (TMDL)
The maximum quantity of a particular water pollutant that can be discharged
into a body of water without violating a water quality standard. The amount
of pollutant is set by the US Environmental Protection Agency.
Total nitrogen concentration is the total amount of nitrogen in one liter of water. Total nitrogen includes both dissolved nitrogen in the water column and particulate nitrogen contained in algal cells and in organic detritus such as degrading leaves from trees.
total organic carbon (TOC)
A measure of the amount of organic materials suspended or dissolved in water.
total suspended solids (TSS)
The weight of particles that are suspended in water. Suspended solids in water reduce light penetration in the water column, can clog the gills of fish and invertebrates, and are often associated with toxic contaminants because organics and metals tend to bind to particles. Total suspended solids are differentiated from total dissolved solids by a standardized filtration process, the dissolved portion passing through the filter.
The ability of a chemical substance that has the potential of causing acute or chronic adverse effects in plants, animals, or humans.
The rills, brooks, and streams that flow into a major river.
A measure of the cloudiness (reduced transparency) of water, determined by the amount of light reflected by particulate matter in the water.
Conditions in soils when infiltration is still possible and media contains both air and water.
The zone between the ground surface and the water table that contains both
air and water.
A subsurface zone containing water under pressure less than that of the
atmosphere, including water held by capillarity; and containing air or gases
generally under atmospheric pressure. This zone is limited above by the land
surface and below by the surface of the saturated zone, i.e., the water table.
The elevated lands above a floodplain or other low-lying areas.
The dry habitat along the sides of a river above a flood plain.
Becoming urban, specifically the concentration of population into towns and cities. Associated with this process is the replacement of pervious surfaces
with impervious materials such as asphalt and concrete.
vegetated filter strip
Created areas of vegetation designed to remove sediment and other pollutants
from surface water runoff by filtration, deposition, infiltration, adsorption,
decomposition, and volatilization. An area that maintains soil aeration as
opposed to a wetland, which at times exhibits anaerobic soil conditions.
A vector measurement of the rate and direction of motion. The scalar absolute
value (magnitude) of velocity is speed. Velocity can also be defined as rate
of change of displacement or just as the rate of displacement, depending
on how the term displacement is used. It is thus a vector quantity with dimension length/time. In the SI (metric) system it is measured in meters per second.
Describes the existence and movement of water on, in, and above the Earth. Earth’s water is always in movement and is always changing states, from liquid to vapor to ice and back again. The water cycle has been working for billions of years and all life on Earth depends on it continuing to work.
Land area that drains to a common waterway, such as a stream, lake, estuary, wetland, or ultimately the ocean. The land area drained by a river and its tributaries; also called catchment, drainage area, or river basin.
An area that is covered by water at least some part of the year. Sufficient
moisture is present so that soil is wet a significant period of time every
year. Plants, humans, and other animals have adapted special techniques for
surviving in the special environmental conditions present in wetlands.