Hughenden Stream is an example of a winterbourne, being fed by ground water held in the chalk that bubbles up in springs. Chalk is an aquifer, which means that it is able to soak up and hold water, which then moves through the chalk in cracks called fissures. Since groundwater levels in the chalk vary according to rainfall and season, chalk streams are naturally intermittent in their flow and often only flow in late winter and early spring. During the winter, when rainfall is heavy and able to percolate through the chalk, the aquifer will be well topped up. The head of the stream moves up the valley as the water table rises.
In summer, little rainfall percolates into the chalk as it is mostly taken up by
plants and lost through evaporation. The water table drops and the head of the stream moves down the valley, leaving the top section of the stream dry. Winterbourne streams in good condition can support wildlife species that are specially adapted to cope with these intermittent flows.
Chalk streams have clear, base rich water, which stays at a fairly consistent temperature and stable flow because it is filtered through the chalk. This, alongside the extreme seasonal flow patterns of a chalk stream makes then a rare and unusual habitat for wildlife. In conjunction with a gravel substrate, the stable temperatures support an abundant and diverse invertebrate community.
Insect and Plant Life
Some invertebrates which are commonplace in winterbourne streams include the larvae of caddis flies, mayflies, stoneflies, and crustaceans including the freshwater shrimp and water hog louse. Key indicator species of a quality winterbourne steam include a rare mayfly (Paraleptophlebia werneri), which has adapted its life cycle to the winterbourne streams annual flow cycle. Mayflies require clean water and lots of emergent and marginal plants, therefore they are a very good indicator of when a chalk stream habitat is thriving. Also the diving beetle (Agabus biguttaltus), which retreats into the stream bed when the water stops flowing. Southern damselfly may also be present.
Chalk streams have characteristic plant communities, often dominated mid-channel by river water crowfoot (Ranunculus penicillatus var pseudofluitans) and starworts (Callitriche obtusangula) and along the margins by watercress (Rorippa nasturtium-aquaticum) and lesser water parsnip (Berula erecta).Specific to winterbourne streams is brook water crowfoot (Ranunculus peltatus), which has adapted to the ephemeral flow regime. Plants provide shelter for water snails and other invertebrates, which provide food for many other species.
The Stream through Hughenden Park
Until the early 19th century the stream was a minor winterbourne feeding the River Wye. There is some evidence of Roman period occupation. The stream apparently had one or more mills associated with it, which are likely to have had related pools to provide a head of water. The site of the medieval mill in the park is unclear, but by the early 19th century a mill called the Flint Mill was located in what became the south park, south of Ford Lane.
During the 19th century, a number of changes affecting the stream were made as the landscape of the park developed. Small fields south of the church were amalgamated, and more land to the east included in the park. The stream was moved westwards, bridges built, an island created and the ponds developed for holding fish, with picturesque rocky weirs. During Disraeli’s tenure, the stream was actively stocked with trout and swans were encouraged as residents.
The Stream North of the Park
The Hughenden Stream is seen at its best running through the park and indeed flows there more often than in its upper reaches. Northwards from the park, it flows through National Trust farmland into Hughenden Valley. At the Spring Rising pumping station, it crosses the road and is culverted through the small industrial estate.
From there it runs broadly parallel with Valley Road through back gardens and a further section of culverting before emerging into the Hopkins farm field. It then runs through a further series of back gardens before being piped under Valley Road as far as the Harrow pub. At the Harrow, it crosses Warrendene Road and runs in a ditch at the side of the road through to the top of Warrendene Road.
Although only flowing occasionally, this section of the stream has a past history of usage including the growing of watercress at Boss Lane, the keeping of ducks, and the watering of livestock.
Organisations Conserving the Stream
Several voluntary organisations take an active interest in conserving the stream. Where the stream runs through Hughenden Park, it is taken care of by the National Trust. Other organisations involved are:
Chilterns Chalk Streams Project
Representing the Chiltern Society on the Chilterns Chalk Streams Project, this partnership of local government, Environment Agency, Countryside Agency, Natural England, water companies and other groups interested in the environment, aims to conserve and enhance all major chalk streams in the Chilterns AONB by:* Raising awareness of the value of chalk streams as a globally rare habitat
* Giving advice to landowners on riverside management
* Undertaking conservation exercises to improve the streams for wildlife
* Doing surveys to assess habitat quality and populations of rare species
* Creating educational material for schools.
Meetings of the Group are held twice a year, usually in October and March. Each meeting will normally have a guest speaker. Subjects addressed are truly catholic and have included the geology of the Chilterns and its impact on the rivers, the history of watercress production, water voles and their habitat, chlorine and its use in water treatment.For more information:
The Chiltern Society: http://www.chilternsociety.org.uk
Chalkstreams Project: http://www.chilternsaonb.org/about-chilterns/chalk-streams/chalk-streams-project.html
Revive the Wye
The Revive the Wye Partnership was formed in 2007 with an aim to protect and improve the natural environment of the River Wye and to make it a special place that people can enjoy and in which wildlife can flourish. The group have launched Friends of the Wye, where those interested in learning about and caring for the Wye can participate. Its aims are to promote and support the protection and improvement of the natural environment of the River Wye, its adjacent corridor back streams and tributaries, for the benefit of the public and wildlife.
For more information go to the Revive the Wye Partnership web site at http://www.revivethewye.org.uk/support-us/friends-of-the-wye.
Chiltern Society www.chilternsociety.org.uk
Chiltern Society AONB www.chilternsaonb.org
Revive the Wye www.revivethewye.org.uk
The Chalk Aquifer Alliance https://chalkaquiferalliance.wordpress.com/about/