River Misbourne

The River Misbourne rises in a field on the outskirts of Great Missenden in Buckinghamshire, passing through Little Missenden, Old Amersham, Chalfont St Giles, Chalfont St Peter and under the Chiltern railway line and the M25 motorway to its confluence with the River Colne just north of where the Colne is crossed by Western Avenue, the A40 road. It falls by around 94 m (310 ft) in the course of its 27 km (17 mi) length.

River Misbourne
River Misbourne near Chalfont St Giles
Location
CountryEngland
Physical characteristics
Source 
 • locationGreat Missenden
Buckinghamshire
 • coordinates51°42′36″N 0°42′44″W
 • elevation129m
Mouth 
 • location
River Colne near Denham
 • coordinates
51°33′43″N 0°29′01″W
 • elevation
34m
Length27km (16.8 miles)
Basin features
River systemThames

Etymology

The name Misbourne is first attested, in the form Misseburne, in 1407.[1]: 73  The -bourne element is agreed to derive from Old English burna ('stream, river'), but the etymology of the first element is uncertain. It is thought to occur in the names of both Great and Little Missenden, and also in the Tring place-name Miswell. Frank Stenton and Allen Mawer guessed that it came from a hypothetical Anglo-Saxon personal name Myrsa, which they also supposed to be found in the name of Mursley.[2] Eilert Ekwall suggested that it came from a lost Old English word related to English moss, and to Danish mysse and Swedish missne (which denote plants of the genus Calla, such as water arum).[3] Recent researchers have tentatively preferred Ekwall's guess, in which case the name Misbourne would once have meant something like 'river where water-plants/marsh-plants grow'.[4][5]: 54–55, 73 

History
River Misbourne was diverted via culverts under M25 motorway. This is the downstream portal of the culvert. The railway viaduct is visible over the trees in the background.

In 1906 the Great Western Railway (GWR) constructed the Chalfont Viaduct to carry trains between London and High Wycombe across the river. In the mid-1980s, when the M25 was being constructed, the Misbourne was diverted under the motorway via underground concrete culverts. The route of the motorway was then aligned to pass through the arches of the Chalfont Viaduct.[6][7]

Flow

The river flows over a bed of impermeable material on top of a porous substrate. This state is only quasi-stable since in periods of low rainfall the water table drops below the level of the impermeable layer. If groundworks are then carried out which damage this layer, the river can sink into the porous substrate and disappear.

The Misbourne has had intermittently reduced or stopped-flow due to abstraction for domestic supply from the aquifers feeding it. This has caused its course to be neglected to lead to partial obstruction. When the water company undertook remedial measures to restore the flow, there were episodes of flooding in both Chalfont St Peter and Chalfont St Giles. Subsequent work has restored the integrity of the course. The upper part of the river was dry for over 3 years starting in November 2003 but re-appeared in February 2007 following several months of above-average rainfall which raised the water table.[8]

References
  1. Hough, Carole, 'Place-Name Evidence for Anglo-Saxon Plant-Names', in From Earth to Art, the Many Aspects of the Plant-world in Anglo-Saxon England: Proceedings of the First ASPNS Symposium, University of Glasgow, 5–7 April 2000, ed. by Carole Hough, Costerus New Series, 148 (Amsterdam and New York: Rodopi, 2003), pp. 41-78.
  2. A. Mawer and F. M. Stenton, The Place-Names of Buckinghamshire, English Place-Name Society, 2 (Cambridge: Cambridge University Press, 1925).
  3. Eilert Ekwall, The Concise Oxford Dictionary of English Place-Names, 4th edn (Oxford: Oxford University Press, 1960), p. 328 (s.v. Misbourne).
  4. A. D. Mills, A Dictionary of English Place Names (Oxford: Oxford University Press, 1991), p. 330.
  5. Hough, Carole, 'Place-Name Evidence for Anglo-Saxon Plant-Names', in From Earth to Art, the Many Aspects of the Plant-world in Anglo-Saxon England: Proceedings of the First ASPNS Symposium, University of Glasgow, 5–7 April 2000, ed. by Carole Hough, Costerus New Series, 148 (Amsterdam and New York: Rodopi, 2003), pp. 41-78.
  6. Kelly, Alison (2009). "Chalfont Viaduct Buckinghamshire - Historic Building Recording" (PDF). Oxford Archaeology. Archived (PDF) from the original on 20 September 2018. Retrieved 20 September 2018.
  7. Hamilton, Ray (2015). M25: A Circular Tour of the London Orbital. Summersdale Publishers Limited. ISBN 9781783726561. Retrieved 20 September 2018.
  8. Misbourne starts flowing again (Bucks Free Press article)

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