Essex Rivers Hub

Glossary

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

Buffer Strip – a strip of land along the river bank that is left unmanaged and has abundant vegetation present. Usually this term refers to strips separating arable land from water courses.

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

Catchment – an area with several, often interconnected water bodies (rivers, lakes, groundwater and coastal waters).

Catchment Partnership – the bringing together of various organisation, stakeholders and other interested parties to work on a catchment based approach. To agree and deliver strategic priorities for the catchment.

Catchment Based Approach – to look at the catchment as a whole to solve problems and to work cooperatively with other interested parties. To balance environmental, economic and social demands and align funding and actions to being about long term improvements to the catchment.

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

Ecological Status – this measures the influence human impact has had on the river environment. Water Framework Directive's (see below for definition) classifications are high, good, moderate, poor and bad. High indicates the least human impact and bad the most.

Eutrophication – when fertilisers are washed off the land by rainwater into rivers and lakes it increases levels of nitrates or phosphates in the water. This encourages algae growth, which forms a bloom over the water surface, which prevents sunlight reaching other water plants, causing them to die back and reduce in number. Bacteria break down the dead plants and use up the oxygen in the water so the water environment can, in extreme cases, be left completely lifeless.

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.

Ochre – a red staining that occurs when iron rich soils or rock leach into the water from surrounding banks. This can be damaging to the river environment if the problem is severe.

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.

Phosphate/phosphorous – this is found in fertilisers and also in the human body. If high levels get into the water environment (through sewage and/or fertilisers washing off fields/gardens into rivers, etc.) this can result in eutrophication occurring (see above for definition).

Physical modifications – alterations which people have made to the form of the river. They include weirs, 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.

Poaching – trampling caused by cattle and other livestock.

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 usually over stones, pebbles or gravel creating a ripple effect on the surface of the water.

Sedimentation – a build-up of sediment (soil and other debris washed into the water from the banks) in the water course causing the water to become cloudy and usually brown – black in colour. Build of sediment can lead to sediment 'banks' developing which can alter the water flow. Sediment in the water course can be detrimental to fish as it can block their gills and can smother invertebrates that live on the river bed.

Sewage Fungus – a grey/brown substance that builds up on the river bed when sewage, high levels of phosphate from fertilisers or other organic materials (oils, fats, etc.) are present in the water. This is a mixture of fungus and bacteria.

Water Framework Directive – a European Directive that requires all rivers to be of good ecological status and to tackle river based problems on a catchment based approach (see above for definitions on ecological status and catchment based approach).

Woody Debris – when parts of trees and other woody plants are found within the water environment and usually having an impact on the flow. Branches, large limbs, root boles or entire trees that have fallen into rivers are commonly referred to as Large Woody Debris while accumulations of smaller branches, twigs and leaf litter are known as Coarse Woody Debris. These can be great habitats for many species and should not always be seen as a flood risk.

Side7 Glossary

Website key stakeholders:

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Design by LTD Design Consultants and build by Garganey Consulting based on an original concept by Herts and Middlesex Wildlife Trust