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www.managingwater.co.uk Managing & Maintaining our water channels


flows from inundating the floodplain, as would naturally occur, and force flow downstream carrying with it large amounts of sediment. As part of the scheme we have removed sections of embankment to encourage floodplain wetting during periods of high flow. This should have the combined benefits of increasing floodplain biodiversity and providing a sink for suspended sediment, as well as reducing flood risk to people and property in the downstream catchment. The level at which water will spill on to the floodplain has been set so that there is a low probability of summer flooding and therefore minimal impact on the agricultural use of grazing marshes.


Having a flow gauging station immediately upstream of the scheme has provided valuable data for the restoration design process, but has also imposed a restraint in that any physical changes to the river must not impact on the accuracy of the gauging station. Situated within the floodplain is an Internal Drainage Board main drain and the floodplain connection works have needed to ensure that the drain does not become surcharged with flood water which could have adverse impacts on downstream landowners. This has been overcome by working with the existing topography and using spoil to locally raise sections of the floodplain to create an isolated area which will wet up during high flows. The other important element of floodplain connection has been to provide a route for water to drain back to the river once river levels have receded.


left: Meander loop pre-works.


below: Downstream section of reinstated meander loop with brush wood berm created using locally won material


felled to enable access for machinery.


above: Over wide river channel pre-works


right: Composite filled berms have been designed to influence water at levels up to Mean Daily Flow. Above this they drown out, creating a two-stage channel.


LATTENBURY SERVICES ‘Caring for the


Countryside’


Watercourse Management


Channel maintenance Dredging Silt Traps Vegetation Maintenance Weedscreens Bank retention Culverts


Water Storage


Bridges & Footbridges


Civil Works


Reservoir Construction Lake & Pond construction


Bridges Walkways


Dipping platforms


(English Oak, Softwoods, Steel or recycled plastic)


Street Works Fencing Footpaths Carparks


Tel: 01480 830224 lattenbury@aol.com


www.lattenburys ervices.co.uk Lattenbury Farm, Godmanchester, Huntingdon, Cambs, PE28 9PA


www.fadsdirectory.com


above: Bed raising using gravel to create glide. In total 6 glides have been installed along the 800m length of river being restored.


below: Berm during construction showing how reject gravel is used to create the shape of the feature. Spoil from historic dredging is locally won as backfill material, then bankside vegetation is replanted along the margin to prevent erosion during high flows.


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