Messing about with the River

Afforestation:
The establishment of a forest or stand of trees in an area where there was no forest. In the context of the River Sid, it is a catchment-wide issue affecting the river.

Alevins:
Young fish, especially salmon or trout, that have recently hatched from the egg and are still largely dependent on the yolk sac for nourishment. They remain in the gravel bed for protection.

Alluvium:
A deposit of clay, silt, sand, and gravel left by flowing floodwater in a river valley or delta, typically producing fertile soil. Found in the floodplain of the River Sid.

Anthropogenic Intervention:
Changes or impacts on the natural environment resulting from human activity. Examples include straightening the River Sid and building weirs.

Armored (Riverbank):
Refers to riverbanks that have been reinforced or protected with hard materials like concrete, rock, or other structures to prevent erosion. The west bank of The Ham on the River Sid is an example.

Catchment Area:
The area of land where all precipitation drains into a common outlet, such as a river, lake, or reservoir. The River Sid's catchment area is about 40 km².

Colluvium (Hillwash):
Loose, unconsolidated sediments that have been deposited at the base of hills or slopes due to gravity, often after deforestation.

Crayfish Plague:
A highly lethal fungal disease carried by Signal Crayfish that is deadly to native white-clawed crayfish, leading to their widespread decline.

Dippers (Cinclus cinclus):
A type of songbird uniquely adapted to fast-flowing streams and rivers, known for their ability to walk underwater to find food.

Erosion System:
Refers to a part of a river where the primary process is the wearing away and transportation of sediment, especially common in the upper, steeper reaches.

Exposed Riverine Sediments:
Dynamic shoals of bare sand and shingle found along rivers, providing microhabitats for specialist invertebrates and nesting sites for certain birds.

"Flashy" Catchment:
A term describing a river system where water levels can rise and fall very rapidly, often within a few hours, in response to rainfall. The River Sid has this characteristic.

Fulling Mills:
Historical mills that used water power to "full" or thicken woven wool cloth by beating and cleaning it. Mentioned as a historical land use demonstrating human interaction with river flow.

Gammarus:
A genus of freshwater shrimps, often used as an indicator species for clean water in river health assessments.

Green and Blue Solutions (SuDS):
Sustainable Urban Drainage Systems (SuDS) are a range of measures designed to manage surface water runoff in a more natural way, mimicking natural processes. "Green" solutions use vegetation, and "blue" solutions involve water features.

Groynes:
Low structures built out from the shore into the water to prevent beach erosion or to trap sand. Built at the River Sid's mouth for coastal protection.

Himalayan Balsam (Impatiens glandulifera):
A non-native invasive plant species common along riverbanks, known for forming dense stands that out-compete native plants and spreading rapidly via seeds.

Holocene:
The current geological epoch, which began approximately 11,700 years ago after the last major glacial period, characterized by a warmer climate and significant human impact.

Impermeable Surfaces:
Surfaces that do not allow water to infiltrate into the ground, such as concrete, asphalt, and roofs, leading to increased surface runoff.

Invasive Non-Native Species (INNS):
Species introduced to an ecosystem that are not native to it and cause environmental or economic harm. Examples in the River Sid include Himalayan balsam, Japanese knotweed, and Signal Crayfish.

Japanese Knotweed:
A highly aggressive and problematic invasive plant species known for its rapid growth, ability to damage infrastructure, and difficulty of eradication.

Longshore Drift:
The process by which sediments are transported along a coastline by wave action. This process led to the growth of the shingle ridge at the River Sid's mouth.

Macrophytes:
Aquatic plants that are large enough to be seen with the naked eye. Their presence and type can indicate water quality.

"Misfit Streams":
Streams or rivers that appear to be too small for the valleys they occupy, often suggesting the valleys were formed by larger flows in the past (e.g., Pleistocene meltwaters).

NTU (Nephelometric Turbidity Units):
A unit used to measure the turbidity (cloudiness) of water, which is caused by suspended solids.

Nutrient Enrichment:
The excessive input of nutrients (like nitrogen and phosphorus) into a freshwater habitat, often from agricultural or sewage runoff, leading to problems like algal blooms and oxygen depletion.

Odonata:
An order of insects that includes dragonflies and damselflies, whose nymphs spend their lives in water.

Oligotrophic:
A term describing a body of water that is low in nutrient content, generally clear, with sparse plant and plankton growth. Fast-flowing streams are often oligotrophic.

Otters (Lutra lutra):
Semi-aquatic carnivorous mammals that are apex predators in many freshwater ecosystems. Evidence of a population exists on the River Sid.

Phytoplankton:
Microscopic photosynthetic organisms that live in aquatic environments; not a key part of the flora in fast-flowing rivers as they are washed away.

Pleistocene:
A geological epoch that lasted from about 2.6 million to 11,700 years ago, characterized by cycles of glaciation. Valleys like the Sid's may have been formed by Pleistocene meltwaters.

ppm (Parts Per Million):
A unit of concentration, often used for dissolved solids in water.

Redds:
Carefully constructed depressions or nests on the riverbed, typically made by salmonid fish (like salmon and trout) for laying their eggs.

Riparian Habitats:
The areas of land adjacent to rivers and streams, crucial for supporting diverse plant and animal life and influencing water quality.

River Fly Species:
Common name for aquatic insect larvae and nymphs (like mayflies, stoneflies, and caddisflies) whose presence and diversity are used as indicators of river health and water quality.

Scour:
The erosion of the riverbed or banks by the abrasive action of flowing water and sediment. The "flashy" nature of the Sid can cause it to scour tributaries.

Sediment Beds:
Areas on the riverbed where loose materials like sand, gravel, and silt accumulate. These can be important habitats but are vulnerable to disturbance.

Signal Crayfish (Pacifastacus leniusculus):
A large, aggressive, invasive freshwater crayfish from North America, known for outcompeting native crayfish and causing ecological damage.

Spate:
A sudden flood or rush of water in a stream or river, often after heavy rainfall.

Spraint:
The faeces of an otter, often distinctive in appearance and used as a sign of otter presence.

Substrate:
The material that forms the bottom of a river or stream, such as rock, gravel, sand, or silt.

TDS (Total Dissolved Solids):
The total amount of solid matter that is dissolved in water, measured in ppm. High levels can indicate pollution.

Training Wall:
A structure built along a river or channel, often near its mouth, to guide the flow of water and prevent erosion or sediment build-up.

Tributaries:
Smaller streams or rivers that flow into a larger river. The Snod Brook, Roncombe Stream, Wool Brook, and Snail Breck are tributaries of the River Sid.

Turbidity:
The cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air.

Weirs:
Small dams built across a river or stream to raise the water level upstream or to control flow. The School Weir on the River Sid is a notable example.

Woody
Debris/Log Jams: Fallen trees, branches, and other wood in a river. When left in place, they create important microhabitats, modify flows, and support diverse aquatic life.