"Walks in the Misbourne Valley" Notice

Image: © David Hillas Taken: 27 Apr 2016

This notice is located at the entrance to the Link Road car park in Great Missenden. It says the following: The River Misbourne - a "winterbourne" Running alongside this car park is the course of the River Misbourne. Its source lies about 1km north of here, near Mobwell Pond, and it meanders down to Denham where it joins the River Colne 17miles/27km away. The Misbourne is special because it is a chalk stream - an internationally rare wildlife habitat. Chalk streams are mostly fed from groundwater rather than surface run-off. The underlying chalk soaks up water like a sponge. This water bearing rock is called an "aquifer". Groundwater emerges from it as springs to feed the streams. Since groundwater levels in the aquifer fluctuate according to rainfall, chalk streams are naturally intermittent in their flow. The upper section of the Misbourne is especially prone to drying up and is called a winterbourne. This section of the river only flows after heavy winter rain has recharged the chalk aquifer, causing groundwater levels to rise. Seasonal changes in a winterbourne stream. In winter The water table will be at its highest after winter rainfall. In summer The water table drops through the summer as there is less rainfall and increased uptake by plants. Rescuing the River The River Misbourne is a valuable local resource for many reasons including wildlife, water and recreation. The chalk acts as a superb filter for rainwater and produces very pure and healthy drinking water. As the local population grew over the 20th century, so water abstraction from the aquifer increased. This lowered the water table and caused the flow of the river between here and Chalfont St Peter to become highly intermittent. In drought years the river virtually dried up. A River Rescue Scheme began in 1997. Abstraction of groundwater from pumping stations along the valley was reduced, allowing groundwater levels to recover naturally. Three Circular Walks Three circular walks have been created to celebrate the river's recovery. Walk 1 starts from here and loops around Great Missenden. You can pick up the "Walks in the Misbourne Valley" leaflet from local public information points, including the Library and Parish Council Office in Great Missenden. Images of Mobwell Pond, Church of St Peter and Paul and Missenden Abbey can be seen on the noticeboard together with a plan of the River Misbourne with its three walks indicated on it.

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