Week Commencing 8th August 2016 - Saltmarsh
The saltings restoration work is now in its 3rd phase following delivery of the materials earlier this month. The final phase will be completed following the last delivery of materials at the end of August.
The initial works to the toe of the section either side of the sluice were completed first and this work is settling in well. This fencing was designed to create a low ‘wall’ in front of the remaining fringe of saltmarsh with a view to slow erosion to the remaining marsh and hopefully promote accretion behind the fence. We have created some ‘groynes’ coming off the main fence line to slow flows as the water ebbs out of the large man-made channel area.
We have created a large bay from Crystal Creek quay in front of Swan's Nest as this area had no marsh left at the toe of the wall, leaving the defence vulnerable for the future.
The work at the northern end, where we have the worst ‘fragmentation’ of marshes, has been completed and this takes the form of an additional row of fencing parallel to the 2015 works as well as some cross walls to try and reduce flows. In this area we have tried to create a couple of ‘raised beds ’ where there is a watershed between creeks with a view that if we can build up the sediment into a hump the flows can no longer meet in the middle and this reduces erosion.
The next phase is to move south and undertake localised protection within the marshes just offshore from the sluice. This will involve closing off bays to create ‘stilling ponds’ which will hopefully accrete and generate new marsh.
The last delivery of materials is planned for late August and so we hope to have works completed in September, well ahead of our October deadline.
The whole site has now been flown with a GPS drone so we have a good baseline survey for future years' monitoring. The initial 6 month monitoring results from the 2015 polderwork has shown 7-10mm siltation behind the fencing with no change on the marsh outside. This is a significant result, especially over a winter monitoring period and gives an indication of what we might expect elsewhere on the marsh where polders are in place.
Report and images courtesy of Karen Thomas, Project Manager for Broads, East Suffolk & Norfolk Rivers Internal Drainage Boards