Start Date
June, 2012
End Date
December, 2014
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River Nar, Sediment Trapping

This project has now been completed. Over the last 2 and half years this project has achieved so much and engaged many local communities in the River Nar catchment. Many farmers within the catchment participated in the project by installing silt traps on their land, planting hedgerows, moving gateways and installing track drains. All these options that have been chosen will help reduce soil loss in fields and capture silt before it enters the river.

What is The River Nar Project?

The Norfolk Rivers Trust is working with WWF-UK and Coca-Cola collaborating on a UK Freshwater Partnership, which will work on vulnerable UK chalk streams. The partnership will ensure the River Basin Management Plans support the achievement of Good Ecological Status by 2015, by addressing key issues such as water quantity, water quality (pollution) and habitat improvements.

What is the problem?

In Norfolk many river catchments are threatened by over-abstraction of water, extensive habitat loss and water pollution. Agriculture is one contributor to water pollution, which can occur when soils are managed in certain ways. For example when soils are cultivated in very wet conditions it could cause structural damage in soils, which can lead to compaction, promoting water runoff and soil erosion. Sediment travelling into the river from point and diffuse sources is a big problem in the river catchment. This affects certain species such as brown trout because they need sediment free gravel to lay their eggs into; allowing the eggs to be well oxygenated.

What is the Solution

Norfolk Rivers Trust has promoted changes to the environment to help reduce pollution such as sediment from entering the River Nar. The money from the WWF-UK & Coca-Cola Partnership and Catchment Restoration Fund would support ‘in-ditch’ restoration options such as reedbeds, wet-willow woodlands, sediment ponds and traps and marshy areas. These options will give sediment time to settle and filter out before the water continues to flow down into the river.

The River Nar Project and you

Do you live along the River Nar, or have a connecting ditch on the map above, walk the river and its tributaries regularly or know it well for some other reason? If so, please get involved in our project. We would like as many local people as possible to share their knowledge of the river and participate in the enhancement and protection of this quiet waterway. We would like to encourage those living and working in the river catchment to participate in its care beyond the end of the project, binding communities into the management of their own precious natural resources.

What action should we take?

The Norfolk Rivers Trust are using the funds from the WWF-UK & Coca-Cola Partnership and the Catchment Restoration Fund to offer 60% funding for each project that could put these restoration options into place. If you know of any areas where these options could be installed, please contact me.

Sediment Trapping

West Acre Road Silt trap Swale

20th June 2014

This swale silt trap has been completed and is working very well. The site where we planned to put the silt trap swale is a Scheduled Ancient Monument, it has been designated because of the West Acre Priory within the meadow, this meant that before the work started we had an archeological dig to see whether anything was present. After one day the archeologists concluded that there was nothing there and we could carry on with the swale construction.

South Acre Road Silt trap

9th December 2013 Norfolk Rivers IDB finished the silt trapping work in Castle Acre on South Acre Road near the ford. The Highways have installed the road to camber to direct the water flow from the road into the ditch sediment trap.

Castle Acre Silt Trap, Common Road

07 November 2013 This is the second silt trap that has been put in near Castle Acre Common. It isn’t like the other silt traps that I have put in because it doesn’t hold water. There is a line of flint which covers a perforated pipe at the back of the silt trap to allow drainage of water from the track. In the spring this area will look more appealing when the vegetation grows up on this site.

Castle Acre Common Silt Trap

04 September 2013 The Norfolk Rivers Drainage Board started work at Castle Acre yesterday to install a sediment pond to capture water running down the tracks near Castle Acre Common. Heather Wallis the Archaeologist on site was watching the diggers as they dug the pond just in case they revealed anything of interest.

Lexham Silt Trap 1 and 2

03 May 2013 Two sediment traps have been constructed at Lexham Hall Estate. Both of these silt traps filter sediment out of the water that flows through ditches before entering the River Nar.

Norfolk Farm Produce in-ditch sediment trap

26 March 2013 This is our third sediment trap, it is located on a tributary of the River Nar. It is a ditch that flows regularly during the winter on Norfolk Farm Produce land. The ditch has been transformed into sediment trap by digging a deep section before the first riffle, then in the second area the ditch has been deepened with two excavated levels on the side of the ditch to allow the water to slow and drop any sediment.

The pond and swale system on the River Nar

29 October 2012 To reduce the amount of sediment from getting into the River Nar a pond which the river flows through was dredged so the water flowing into it could settle out the suspended sediment before continuing down stream. STAGE1 – The pond The pond was constructed over 40 years ago and since then it has gradually filled up with silt deposited from the water. The diggers dug down to just over a meter deep and used some of the silt to create a jetty. This jetty will enable the diggers to access the site again to remove the deposited silt at a later date (est. 5-10 years time). A conservation area was also made with a barrier to allow clean water to flow over the top and into an area where the pond bed shallows. When water levels are low the conservation area will hold water throughout the year. STAGE 2 – Swale The River Nar flows into the pond and to give the flowing water more chance to deposit sediment a short section of the river was made into a swale. This means creating a shallow scrape for the water to flow onto reduce flow speed and drop the sediment into the grass.