Glossary

Terms used and their description

Algae -simple plants, mostly microscopic without roots and leaves.

Anabranch -  a secondary channel of a river that leaves the main channel and re-joints it further downstream.

 Aquifer- an underground layer of soil, rock or gravel able to hold and transmit water.

Barrage – a construction across the mouth of a river that prevents the entry of seawater; behind a barrage’ the water is fresh.

Billabong – a river meander that has been cut off and become isolated from the main channel.

Biodiversity – biological diversity or the variety of life forms, comprising genetic diversity (within species), species diversity  and ecosystems diversity.

Blue-green algae – also known as cyanobacteria. Naturally occurring, microscopic, primitive photosynthetic bacteria. 

Catchment – Area of land from which all surface water drains to a common destination, such as a lake of a river.

Ecosystem – an interdependent biological system involving interaction between living organisms and their immediate physical, chemical and biological environment.

Environmental Flows – flows, or characteristics of the flow pattern, that are either protected or created to benefit the natural environment.

Extraction – water taken from rivers for off stream use or consumption

Fishway – a structure designed to enable fish to move over a physical barrier (dam or weir) in a waterway.

Floodplain – relatively flat land beside a river that is inundated when the river overflows its banks during a flood.

Floods – flows that are high enough at their peak to overrun river banks.

Flow regime -  the pattern of flow in a river which can be described in terms of the quantity and variability of water flows. 

Gigalitre (GL) – one thousand million litres

Groundwater- sub-surface water contained in a saturated zone of soil or rock.

Habitat – the type of environment in which a given animal or plant lives and grows, including physical and biological conditions.

Invertebrates – animals without backbones including zooplankton, shellfish, worms, insects, shrimp, crabs and snails.

Kilolitre – one thousand litres

Macroinvertebrates – Invertebrates with a body greater than 1 mm that is, that can be seen with the naked eye.

Macrophytes – literally ‘big plants. The term is usually used to describe water plants other than microscopic algae; they may be floating or rooted.

Megalitre (ML) - one million litres (an Olympic swimming pool is about 2 megalitres).

Micro-organism – any organism not visible to the naked eye, for example, bacteria.

Nutrients – substances, such as phosphorus and nitrogen, that are necessary for plants (including algae) to grow.

pH -  measure of acidity. The lower the pH, the more acidic and less alkaline a substance is.

Photosynthesis – manufacture of carbohydrates by plants using energy from light.

Recharge – Rainfall that drains past the root zone and reaches the groundwater.

Remnant vegetation – Native vegetation that remains after surrounding land has been cleared.

Regulated -  a river or creek where water is released from storage to meet diversions requirements downstream, or to reduce flooding.

Riparian zone – the area along the bank of a river or stream; often has water-dependent vegetation.

Riverine – relating to rivers and their floodplain

Runoff - water that runs off the soil surface. It largely determined by rain intensity and duration, slope, surface cover and soil infiltration rate. Runoff is rainfall that does not infiltrate or evaporate. 

Salinity – the concentration of salts in soil or water, usually sodium chloride.

Salinisation – the accumulation of salts in the soil to a level that causes degradation of the soil. 

Sediment load – the amount of sediment carried by a stream

Snag – fallen trees and dead branches in the river channel.

Stratification – when the water in a dam or weir pool forms layers that do not readily mix with each other.

Tributary – a river of creek that flows into a larger river.

Water table – The upper surface of the groundwater

Weir – a construction across a river that dams the water but may be removable during times of flood.

Weir pools – the water that is held back by the presence of a weir, forming a still body of water.

Wetland – land inundated wish temporary or permanent water that is usually slow moving or station, shallow, and either fresh, brackish or saline.

Zooplankton – floating microscopic animals.

Source: Rivers as Ecological Systems The Murray-Darling Basin
(Murray-Darling Basin Commission)