Glossary

A list of terms, acronyms and their definitions to help anybody who is interested in learning more about rivers, their environment and management.  

Abstraction - taking water from natural sources such as rivers or aquifers for human use such as in homes, farms and industry. 

Alluvium - rock particles (clay, silt, sand and gravel) deposited by a river. 

Aquifer - A layer of rock below the ground that is sufficiently porous and permeable to allow either a significant storage or flow of groundwater. 

Backwater - A small, generally shallow body of water attached to the main channel with little or no current of its own pushed back by a dam or current. 

Bar - An accumulation of alluvium (gravel or sand) in the river, caused by a decrease in water velocity. 

Beads on a String – A term used to describe the landscape surrounding Bury St Edmunds, named after the appearance of the river from satellite photos. The wetlands and meres dotted along the river appear like beads tied on a string.  

Biodiversity - the variety of living species including animals and plants in a habitat. 

Buffer zone - A strip of land adjacent to a watercourse that is protected, often with fencing, from impacts such as livestock grazing. 

CaBA –Catchment Based Approach (CaBA). This is an initiative to maximise the natural value of our river environments by working in collaboration with groups from across society, including local authorities, water companies, businesses and private individuals.   

CamEO –Cam and Ely Ouse Catchment Partnership. This is the larger area that encompasses 5 river catchments: the River Lark, Little Ouse and Thet, Cam, Wissey, and South Levels in the East of England. Since 2025, RLCP has been the host of CamEO.  

CaSTCo – Catchment Systems Thinking Cooperative (Requires a link). This is a collaborative Ofwat project to create a national framework focussed on citizen science and low-cost monitoring of river health.  

Catchment - The area of land from which rainfall flows into a specific river, via surface runoff and groundwater flows.  

Chalk Stream – A river that rises from groundwater in a landscape that sits on chalk bedrock. Chalk streams are globally rare habitats due to their traditionally high water quality, clean gravel beds and consistent annual flows.  

Confluence - the point at which two rivers meet. 

CSF – Catchment Sensitive Farming. This raises awareness of diffuse pollution from agriculture by giving free training and advice to farmers in order to improve the environmental impact of farms.  

CSO - Combined Sewer Overflow - a term used to describe what happens when combined sewer systems become overwhelmed by excess stormwater and overflow into nearby streams and rivers. 

Cut-Off Channel – A man-made waterway, built in the 1960s as a flood defence measure for the Fens. It carries water north from the River Lark, also draining the Little Ouse and Wissey before delivering it downstream to the Great Ouse.  

Culvert - A closed tunnel or pipe carrying a watercourse beneath and obstruction such as a road, railway or canal. 

Diffuse Pollution - Pollution from widespread activities with no one specific source, e.g. agricultural or urban run-off. Collectively significant but which source has which effect is difficult to work out.  

Dissolved Oxygen - A measure of the amount of oxygen in the water. Concentration is the measure of the amount of oxygen in a volume of water. Saturation is a measurement of the amount of oxygen in the water compared to the amount of oxygen the water can actually hold at full saturation. 

EA - The Environment Agency. The government agency with responsibility for protecting the environment and preventing its deterioration in England.  

EFI - Environmental Flow Indicator. This is a measurement used to indicate where an increase in abstraction would have a negative impact on river habitats and species. 

ELMs - Environmental Land Management. This is a set of government schemes that reward farmers for sustainable management of land for environmental benefits.  

Embankment - A bank of earth or stone that prevents the land behind from flooding. 

Emergent - Rooted plants that can tolerate flooded soil but not extended periods of being completely submerged. 

Ephemeral Stream - A stream that flows only in direct response to precipitation and whose channel is at all times above the water table. Ephemeral streams are short-lived, existing only after heavy rainfalls and drying up in between. 

Eutrophication - High nutrient levels in a waterbody leads to excessive plant and algae growth. This can cause a deteriorating process that results in loss of oxygen and the biological death of the river. 

Floodplain - Area of land bordering a river that is prone to flooding. 

Geomorphology – The study of the physical features of the Earth and how they vary over time. Particularly relevant to rivers which are constantly varying.  

Groundwater - Water stored underground in the pores of rock. In the River Lark Catchment, this is stored in the chalk aquifer, which feeds chalk streams. 

Headwater – The collection of small streams that start and join together near the source of a river.  

Lateral Connectivity - the connection between the river, its riparian margins and the flood plain. 

LNRS - Local Nature Recovery Strategies (Requires a link). Norfolk and Suffolk have a combined LNRS that forms a regional plan for nature to help plan and drive more coordinated action and investment. 

Longitudinal Connectivity - the connectedness along the linear length of the river, interrupted by artificial structures and barriers to fish migration, such as weirs. 

Macrophytes - Larger plants, typically including flowering plants, mosses and larger algae but not including single-celled phytoplankton or diatoms. 

Mere – A shallow lake and wetland habitat 

NbS - Nature-based solutions. This involves using and working with nature to solve a societal challenge, such as wetland construction to filter sewage, providing benefits for human well-being and biodiversity. 

NE – Natural England (requires a link).  Government body that aims to conserve and enhance the natural environment for the benefit of present and future generations. 

Perennial Stream - A stream that normally flows year-round because it lies at or below the ground water table, which constantly replenishes it. 

Permeability – The measure of a rock (or any other material)’s ability to allow fluids to pass through it via its pores and cracks.  

Point Source Pollution - Pollution arising from an identifiable and discrete source such as a sewage discharge pipe or a road bridge.  

Porosity – The measure of the ratio of empty spaces in a rock (or any other material), showing the storage capacity for water.  

RAM - Resource Assessment and Management. A technical framework for water-resource management including abstraction licensing. 

Reach - A section of river between two different points. 

Riffle - A reach of river that is characterized by shallow, fast moving water broken by the presence of rocks and boulders. 

Riparian - Along the banks of a watercourse. Riparian zones support riparian vegetation and are of environmental importance, providing diverse habitats and supporting a range of ecological communities. 

Run - A reach of river characterized by deep, low turbulence water 

Scour - The erosive action of running water in streams, which excavates and carries away material from the bed and banks. 

SFI - Sustainable Farming Incentive. A scheme that pays farmers to manage their land in an environmentally sustainable way. 

SO - Storm Overflow. Occurs when raw sewage is discharged directly into a watercourse by a water company, usually during high rainfall events. Anglian Water publish all their storm overflows and their activity here​(https://www.anglianwater.co.uk/environment/storm-overflows/storm-overflow-map/). 

STW - Sewage Treatment Works. Sites that clean wastewater to remove contaminants before returning water to the environment. Also referred to as Water Recycling Centres (WRC). 

Surface Waters - Water bodies above the ground including rivers, lakes, estuaries and coastal waters (i.e. not including groundwater). 

Turbidity - The amount of suspended particles in water, such as clay, silt, and algae. This can be measured as particles cause light to be scattered and absorbed, making it appear cloudy. This is a key measure of river health.  

Turbulent Flow – Irregular, chaotic flow in a river. This is usually caused by high velocity and an uneven bed, occurring most often in riffles.  

Watershed - The land area that catches and drains water to a particular stream or wetland. This is different from a basin, which is an area of land where all the water in an area drains into a large river. There can be many watersheds within an entire river basin. 

WFD - Water Framework Directive. A comprehensive river basin management planning system, originally EU-created but now in UK law, aiming to help improve the condition of our rivers, lakes, estuaries and coastal and groundwaters. This is underpinned by the use ofenvironmental standards to help assess their ecological and chemical health. 

WINEP - Water Industry National Environment Programme. The most significant way that water companies invest in environmental improvement, in order to meet their legal requirements for environmental standards.  

Winterbourne - the ephemeral part of the chalk stream that routinely and naturally dries for a short period each summer. 

WRMP - Water Resources Management Plans. Used by water companies to set out how they intend to achieve a secure supply of water for their customers and a protected environment.