Oregon Water Science Center Glossary | U.S. Geological Survey

A

Acoustic velocity meter

A device that uses sound waves to track velocity of particles moving in the water column.

B

BOD5

BOD5 refers to the five-day biochemical oxygen demand of bacteria and microorganisms decomposing nitrogenous and carbonaceous matter in water.

Backwater

Water backed up in its course by an obstruction (such as a dam), an opposing current, or the tide.

C

CBOD

Oxygen demand of bacteria and microorganisms decomposing carbonaceous matter in water.

CE-QUAL-W2

A water quality and hydrodynamic model in 2D (longitudinal-vertical) for rivers, estuaries, lakes, reservoirs and river basin systems. W2 models basic eutrophication processes such as temperature-nutrient-algae-dissolved oxygen-organic matter and sediment relationships.

Coagulant

A substance that causes a liquid to thicken or clump

D

Diatoms

Diatoms are the base of the food chain in aquatic ecosystems. Any of a class (Bacillariophyceae) of minute planktonic unicellular or colonial algae with silicified skeletons that form diatomite.

E

Eutrophic

A body of water that is rich in dissolved nutrients.

G

Gage height

The height of the water surface above the gage datum (zero point). Gage height is often used interchangeably with the more general term, stage, although gage height is more appropriate when used with a gage reading.

Groundwater

Liquid water stored underground, within cracks in rocks of all kinds and in the pore spaces of sediments and sedimentary rocks. The term “aquifer” refers to rocks that can hold substantial amounts of water. Groundwater can be fresh, saline, or brackish.

Groundwater discharge

Processes through which water leaves a groundwater system. Examples: water resurfaces naturally in springs, lakes, rivers and other water bodies, and from plants consuming water through roots. Human caused discharge occurs from withdrawals through wells.

Groundwater recharge

Processes through which water can enter a groundwater system. Examples: rain and snowmelt infiltration, seepage from water bodies such as lakes, rivers, etc.

I

Impoundments

A body of water formed by a dam.

Isotope

Isotopes are atoms of the same element with different numbers of neutrons. For example, carbon always has 6 protons, or else it wouldn't be carbon. Carbon 12 has 6 protons and 6 neutrons to equal carbon 12. An isotope of carbon - carbon 14 still has 6 protons but has 8 neutrons to equal 14.

M

Mesocosm

An outdoor environment that is designed to determine the effects that different changes have on an ecosystem.

P

Periphyton

A plant assemblage including microbial communities of algae and cyanobacteria living attached to submerged aquatic vegetation.

Permeability

Describes the ability of groundwater to flow through rocks or sediments.

Photosynthesis

Photosynthesis, the process by which green plants and certain other organisms transform light energy into chemical energy. During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds.

Phreatophytes

A deep-rooted plant that obtains its water from near the water table. Phreatophytes often have their roots in constant contact with groundwater.

Pumpage

The amount of liquid raised by pumping.

T

Turbidity

The measure of relative clarity of a liquid. Turbidity is an optical characteristic of water and is a measurement of the amount of light that is scattered by materials in the water.