Recent information from the Alde and Ore Community Partnership has found the remaining walls at Hazelwood marshes could be at new risk of erosion. This is due large volumes of tidal water forming waves, which when driven by northerly winds risk weakening the rear inland side of the walls.
It is thought that there is a dual relationship between the walls being subject to increased erosion and the presence of increased amounts of tidal water at Hazelwood marshes. As the walls weaken, tidal volumes increase in the marsh, which can then lead to increased wave activity impacting the walls at Hazelwood marshes.
Brian Upson owns a boatyard at Slaughden Quay, Aldeburgh, on the bend of the Alde Ore estuary, on a narrow strip of land and shingle, bordered by the open sea on one side and the estuary on the other. Mr Upson believes the tide prism increased once the walls at Hazelwood marshes were breached and was allowed to become intertidal without further intervention.
Following the breach at Hazelwood, the boatyard had to go up a buoy size, to keep the boats tethered. The tide could be 8ft at Aldeburgh, in the open sea, 10 ft at Shingle Street, at the mouth of the Alde Ore Estuary, and at Slaughden, the tide could be 9ft. Mr Upson has observed that 3 or 4 ft has been taken off the mud flats, with the disappearance of mud from the bottom of the estuary.
However, the increase in tidal flow at Slaughden is not quantified. A report by Kenneth Pye, on the 2nd May 2014, 5 months after Hazelwood marshes was breached, concluded that there would only be an increase of the tidal prism of around 6-7%, should Hazelwood marshes be left to become intertidal, with no work done to repair breached estuary walls. The tidal prism is the volume of water that comes in and out of an estuary with the rise and fall of a tide.
A cursory look at the tide levels on tidetimes.org.uk and https://www.thebeachguide.co.uk/south-east-england/suffolk/shingle-street-weather.htm, shows that on Sunday 3rd October, for the years, 2021 back to 2019, the height of the tide at Slaughden, either slightly exceeded the height of the open sea at Aldeburgh, or was slightly below it, with the height of the tide at Shingle Street exceeding both of the height of the open sea at Aldeburgh and the tide height at Slaughden.
The height of the tide is in metres and as can be seen, there is a difference of around 2 hours between high tide at Aldeburgh in the open sea and high tide and Slaughden Quay in the Alde Ore estuary.
Regardless of whether an increase in the tidal prism has occurred and the extent to which it is intensifying, what is noticeable is the small signs of increased erosion around the edges of Hazelwood marshes, away from the breached walls at the sea ward entrance to the marshes.
As has been discussed previously on this blog, scouring continues, into the path on the way to the bird hide.
Scouring is also occurring into the grass bank at the back of Hazelwood marshes, near a small number of houses.
These dwellings are also adjacent to the river part of Aldeburgh golf course, and not far from the main Saxmundham road into Aldeburgh. This could indicate that a question of how to manage sea water volumes in intertidal areas, is something that will need to be considered in the near future.
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