River Glossary

Rivers are complex ecosystems. Their complexity is reflected in a rich and technical vocabulary, which can be daunting and confusing for anyone – those who aren’t fully immersed in a riverine way of life and also experienced river enthusiasts.

Thinking of it, we started a weekly River Glossary series in which we bring river-related words and explore their meanings. Keep an eye on our socials every Friday for new words, or come back here to see the full list.



Abrasion: process in which rocks and sediments wear down the riverbed and riverbanks, contributing to erosion.

Abstraction: the process of extracting water from a natural source (rivers, lakes, groundwater, etc.) for use in agriculture, industry or drinking water supply.

Affluent: a body of water which flows into the largest stream or river, also known as a tributary.

Aggradation: accumulation of sediment in the riverbed and riverbanks resulting in land elevation.

Alluvium: sediment – clay, gravel, silt and sand – deposited by flowing water in the riverbed, floodplain, delta, or at the base of a mountain slope.

Aquifer: underground layer or layers of porous rock, sediment, or soil that hold water and allow it to flow.



Backwater: a part of a river with little or no current.

Basin: an area of land drained by a river and its tributaries.

Bed: bottom of a channel.

Bog: freshwater wetlands with wet, spongy ground where peat accumulates.

Brackish water: water that’s more saline than freshwater, but not as salty as saltwater. It may result from the mixing of fresh and saltwater as in estuaries or man-made projects such as dikes.

Buffer strip: vegetation barrier between aquatic and terrestrial zones designed to filter out pollution before it reaches the water.



Canal: man-made waterways built for irrigation, shipping, travelling and other purposes.

Catchment: an area of land where water collects from the higher areas above it, usually surrounded by hills or mountains.

Channel: the deepest part of a waterway; or a narrow body of water that connects two larger bodies of water.

Channelisation: the artificial process of widening and deepening river channels to improve capacity and/or navigability.

Confluence: the meeting or junction of two or more streams; also the place where these meet.

Culvert: a buried water pipe or sewer that crosses under a road or railway.



Dam: a barrier or structure across a waterway built to control the flow of water.

Degradation: progressive lowering of the riverbed due to sediment removal.

Delta: an area of low, flat land, where a river splits and spreads out into several smaller streams before entering a larger body of water.

Deposition: the process through which the river deposits sediment in the river channel or in its floodplain.

Diversion: re-routing water from a watercourse, permanently or temporarily, for construction or irrigation purposes.

Drainage basin: an area of land drained by a river and its tributaries.



Effluent: stream fed directly by groundwater.

Embankment:  artificial deposit of material used to contain, divert, or store water, support roads and railways, or for other similar purposes.

Erosion: wearing away of rock and soil in the riverbed and banks by biological, chemical, or mechanical forces.

Estuary: an area where a river meets the sea.

Eutrophication:  overabundance of nutrients in a body of water leading to the excessive growth of algae and other aquatic plants. When these plants die and decompose, they deplete the water of oxygen.



Floodplain: an area of flat land near a river or stream naturally subject to flooding.

Flow: the volume of water moving past a particular point during a given time period.

Fluvial: a term used to describe anything related to rivers or streams.



Gravel: natural accumulation of rock fragments, mostly of particles larger than sand (over 2 mm).

Groundwater: water found underground in the cracks and spaces in soil, sand and rock.



Habitat: local environment where organisms live and grow.

Headwater: the source of a stream or river. These are located at the furthest point from where the water body empties or merges with another.

Hydrological cycle: the continuous circulation of water in the Earth-Atmosphere system – from the ground to the atmosphere and back again.



Inlet: a narrow body of water extending into the land from a larger water body such as a sea, lake, or river.

Infiltration: the process by which water enters the ground by seeping through pores in soil or any other surface.



Lake: an inland body of slowly moving or standing water, usually larger and/or deeper than a pond.

Levee: an embankment constructed to prevent a river from overflowing.



Meander: a sinuous curve or bend in the channel of a river or another watercourse.

Morphology: the form, shape, or structure of a stream or organism.

Mouth: where a river enters another river, lake, sea, or the ocean.



Outfall: the mouth or outlet of a river, stream, lake, drain or sewer.

Oxbow lake: a curved lake that was originally a bend in a river but became separated when the river took a new, straighter course.


Peat: spongy material formed by the partial decomposition of organic matter, primarily plants, found in wetlands.

Point source pollution: any single identifiable source of pollution, such as an outfall pipe, ditch, ship, or smokestack.

Pond: a small body of (usually fresh) water smaller than a lake.



Reservoir: an artificial or natural storage place for water, such as a lake, from which the water may be withdrawn for irrigation or water supply.

Riverbank: the land at either side of a river.