| River Misbourne | |
|---|---|
 River Misbourne near Chalfont St Giles | |
 | |
| Location | |
| Country | England |
| Physical characteristics | |
| Source | |
| • location | Great Missenden Buckinghamshire |
| • coordinates | 51°42′36″N0°42′44″W / 51.71000°N 0.71222°W /51.71000; -0.71222 |
| • elevation | 129 m (423 ft) |
| Mouth | |
• location | River Colne nearDenham |
• coordinates | 51°33′43″N0°29′01″W / 51.56194°N 0.48361°W /51.56194; -0.48361 |
• elevation | 34 m (112 ft) |
| Length | 27km (16.8 miles) |
| Basin features | |
| River system | Thames |
TheRiver Misbourne rises in a field on the outskirts ofGreat Missenden inBuckinghamshire, passing throughLittle Missenden, OldAmersham,Chalfont St Giles,Chalfont St Peter and under theChiltern railway line and theM25 motorway to itsconfluence with theRiver Colne just north of where the Colne is crossed byWestern Avenue, theA40 road. It falls by around 94 m (310 ft) in the course of its 27 km (17 miles) length.
The nameMisbourne is first attested, in the formMisseburne, in 1407.[1]: 73 The-bourne element is agreed to derive fromOld Englishburna ('stream, river'), but the etymology of the first element is uncertain. It is thought to occur in the names of bothGreat andLittle Missenden, and also in theTring place-nameMiswell.Frank Stenton andAllen Mawer guessed that it came from a hypothetical Anglo-Saxon personal nameMyrsa, which they also supposed to be found in the name ofMursley.[2]Eilert Ekwall suggested that it came from a lost Old English word related to Englishmoss, and to Danishmysse and Swedishmissne (which denote plants of the genusCalla, such as water arum).[3] Recent researchers have tentatively preferred Ekwall's guess, in which case the nameMisbourne would once have meant something like 'river where water-plants/marsh-plants grow'.[4][5]: 54–55, 73
In 1906 theGreat Western Railway (GWR) constructed theChalfont Viaduct to carry trains between London andHigh Wycombe across the river. In the mid-1980s, when the M25 was being constructed, the Misbourne was diverted under the motorway via underground concreteculverts. The route of the motorway was then aligned to pass through the arches of the Chalfont Viaduct.[6][7]
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 theaquifers 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]
Media related toRiver Misbourne at Wikimedia Commons
