Abstraction – the act of pumping or removing water from the groundwater or a river

Aquifer – underground, permeable rock which can act as a store of water

Canalising – converting a river into a canal-like waterway, usually by installing artificial banks and/or bed and straightening the channel

Dredging – scooping or digging out of the river bed to deepen the channel

Groundwater – Underground water, held in saturated rock or soil

Invasive non-native species – animals or plants found outside their natural distribution, and which cause harm to the environment, people and/or the economy

Macrophytes - a non-microscopic aquatic plant growing in or near water

Meander – a bend in a river. Meanders add variety to a river’s flow, and can promote erosion and deposition of sediment

Morphology – the form and structure of the river channel, e.g. the straightness or depth of the channel

pH - a measure of how acidic a liquid is.  pH 7 is neutral - below this, the lower the pH value, the more acidic it is;  the higher the pH, the more alkaline it is.

Physical modifications – alterations which people have made to the form of the river. They include weirs, and straightening, widening, deepening, canalising or dredging the channel

Phytobenthos - Microscopic plants that live attached to the river bed, or to rocks, stones or large plants within the river channel

Pollution – contaminants which affect the river’s water quality. Examples would be from herbicides, pesticides, organic and artificial fertiliser, sediment, sewage or heavy metals.

Riffle – a stretch of relatively shallow, fast-flowing water

Winterbourne – a stream which flows only after prolonged heavy rainfall leading to high groundwater levels, usually in the winter months

Design by LTD Design Consultants and build by Garganey Consulting. From an original concept by the Herts and Middlesex Wildlife Trust.