The lovely photograph above has been kindly supplied by Carol Walker of the Isle of Wight Photographic Society who are helping us with this project. You can see more pictures of her walk along the Caul Bourne by looking at our Flickr Gallery.
The River Caul Bourne and its tributaries rise from a series of springs emerging on the northern flanks of the Isle of Wight’s central chalk ridge. The spring-fed pond in Westover Manor on the edge of Calbourne village is the source of the main river and it makes it’s public appearance at Winkle Street and then flows for less than four miles across Tertiary sands and clays before entering Shalfleet Lake, part of the Newtown Estuary, and then entering the Solent. The Caul Bourne drains a catchment of approximately 16 km2
Our brilliant local field studies establishment, Medina Valley Centre regularly visit and monitor the Caul Bourne. They have recorded how the discharge from Westover Pond can increase dramatically when the water-table is high following a period of prolonged rain. This video clip shows the river in spate in front of the beautiful chalk cottages in Winkle Street in Calbourne Village. When the water-table rises as the chalk aquifer fills, new springs emerge, pouring out onto the road and into channels which remain dry for most of the year.
On 30th December 1993 there was flooding at Shalfleet when 4 properties suffered. At Shalfleet the river divides upstream of the road bridge. The main watercourse falls some 2m and passes beneath the road bridge. A mill race continues at a higher level for approximately 400 m before falling 3.5 m at Shalfleet Mill at a downstream limit of the river.
The event of 30th December 1993 followed a period of 8-hour duration rainfall with a return period of approximately 7 years. Flood water rose to 0.5m above road level and inundated 4 properties to depths of up to 1.5 m. The combined capacity of the road and mill race culverts were estimated as 10.8 cumec before the threshold of property flooding is reached. Blockage of the main culvert during the flooding substantially reduced this capacity.
In 2014 we mapped all the issues we were aware of with regards to the Newtown Rivers. This map can be viewed here. Please let us know if you know of other issues.
The Technical bits
The Catchment Data Explorer is an Environment Agency tool which helps you explore and download information about the water environment. It supports and builds upon the data in their river basin management plans. Read about the Caul Bourne here. The Caul Bourne is classed as ‘’Moderate’ quality within the Water Framework Directive. It is not expected to improve because of the heavy modifications caused by historic mill infrastructures.
Three IW Steams – Caul Bourne, Lukely, Rodge Brook Observation on Fauna and Water Quality 1987 – 1989