Sudbourne Beach

Mark of The Storm

Erosion of cliffs below North End Avenue, next to Rock Revetment Flood Defence. Thorpeness Beach 5th November 2023.

As storms continue to batter the East Anglian coast, this discussion will consider marks left by storms Babet & Ciaran on two beaches in Suffolk and ask how useful it is to examine erosion through the lens of the Palimpsest. The term refers to how a surface or feature, when something new is added, continues to display residues of what was there before.

Firstly, data for Significant Wave Height (SWH) at Lowestoft recorded the highest values to date for 2023 during Storm Babet and Storm Ciaran. The SWH Storm Alert Threshold for Lowestoft is 3.11 metres. During Storm Babet, SWH was slightly below this and for Storm Ciaran it was noticeably above it.

*Data provided by* *https://coastalmonitoring.org/, The National Network of Regional Coastal Monitoring Programmes, funded in five-year cycles from DEFRA and administrated through the Environment Agency.*

The Tpeak(s) or Dominant Wave Period, (DWP) is the period where the highest wave energy is centred. It is interesting that the DWP is the same for both wave heights. Particularly as the same DWP was also recorded for the highest SWH in 2022, during a storm on 31^st March, when a SWH value of 4.10 metres was registered.

It is also worth noting that the highest value for Significant Wave Height was also recorded at Happisburgh, during Storm Babet on the 20th October. A SWH of 3 metres was registered, with a Dominant Wave Period of 6.2. The Storm Alert Threshold at Happisburgh is 2.74 metres.

Data for SWH has been considered because it enables an insight into the turbulence of the sea. It also provides the first noticeable signs of repetitions or noticeable exceptions. Patterns of wave behaviour that indicate continuity or require a new understanding, that learns from and develops, what has gone before. The first consideration of the usefulness of Palimpsest.

This term is discussed in a doctoral dissertation by Alison Stoneman, titled Holding The Line: contemporary poetry of British coastal change. PhD, Nottingham Trent University. Stoneman critically analyses Coastal Erosion poetry, and refers to storm damage on beaches, as sheets of features, that add to and alter marks left by storms before. Following storms Babet and Ciaran, erosion features of Thorpeness Beach and Sudbourne Beach in Suffolk were observed and will be considered through the lens of Palimpsest.

To start with Thorpeness, it might be quite straightforward to consider the framework of Palimpsest as a useful approach to analyse erosion at this location. As observations of erosion on the cliffs, show recent changes set in the context of the geology of the Pleistocene. Even though the beach changes quite dramatically, remnants of what has been laid down previously still show through. This is particularly relevant when considering the Pleistocene and the Palimpsest. As a couple of the poems analysed by Stoneman refer to Doggerland, a stretch of marshland that stretched between England and Europe, that was inundated by the sea at the end of the last ice age.

Observing current erosion through the lens of Palimpsest, is also useful as it enables a consideration of recent erosion and how this has affected the cliffs differently. Elevated wave action can scour the base and lower portion of cliff surfaces, stripping the surface and causing sediment to slump onto the beach.

At Thorpeness erosion of the cliff frontage, in the last 5 or 6 months has shifted further up the towards the Ness, at Thorpeness. The surface has been partially stripped of the vegetation and glacial til and fossilised remains and this has left bare sand which has been sculpted by wave action. However, the area of beach that has been spared recent erosion has been freshly eroded by Storms Babet and Ciaran. But because it had been stable for a few months prior to this, the glacial till/fossil sediment is still visible on the surface of the cliff and slumped sediment.

Cliffs showing different stages of erosion. Thorpeness Beach 5th November 2023

The next location, Sudbourne Beach provides a different setting in which to consider the Palimpsest. It is a high-energy shifting shingle beach, and in such a dynamic area, it is hard to identify threads of current and past coastal change. Recently, the ridge at the back of the beach has flattened with an extensive wide area of shingle showing signs of overtopping with shingle washed by waves into two tongues down to the marshes. The shingle fan stops short of the waterway behind the earthen flood defence that protects the River Alde.

Flattened shingle showing signs of overtopping by the North Sea to marshes behind a previously protective shingle ridge. Remnants of ridge are visible in immediate foreground of photo. 5th November 2023.

On Sudbourne Beach, it could be hard to see the accumulation of coastal features, intrinsically linked over time, it is only possible to see the effects of what Gillian Clarke’s poem, Cantre’r Gwaelod’, describes as the ‘indifferent hunger of the sea’. Whilst it is possible to see the remains of the Shingle Ridge as it was and the smaller shingle ridge that runs the length of the back of the beach, it would seem to be a coastal location that is very much ‘coming into being’. It would be difficult to identify landmarks that provide clues to the trajectory of the coastline.

Long view of remains of shingle ridge with Alde Ore estuary and North Sea. Sudbourne Beach. 5th November 2023.

But perhaps, such locations should be seen as wild places, seascapes governed by natural forces, especially at a time of storms of increasing severity. Use of the approach of the Palimpsest, could provide tools to look through the local, forceful, intense action of Wind-Wave Storms. According to Stoneman, each erosion feature is distinct, but through its characteristics, relates either by its location or by its form to earlier examples. Use of the Palimpsest as a vehicle to see through erosion and sea state to create methods to interpret future marks of the storm.

Perceptions of Erosion

Erosion into shingle ridge, at top of concrete block flood defences, Sudbourne Beach, near Aldeburgh

This discussion is the second of a series, to debate whether big events, such as surges or high waves, or smaller gradual processes, cause the most erosion. This second conversation will look at erosion at Hazelwood Marshes in the Alde and Ore Estuary and Sudbourne Beach on the open coast. These areas have been selected because they provide examples of both small- and large-scale erosion. To frame this discussion, an initial definition of erosion will be used that describes it as a process that takes away physical substances, from the earth’s surface, mainly earth, sand or shingle and conveys this sediment by weather driven process’s such as wind or water from the focal point being eroded.

To begin with a consideration of Hazelwood marshes, it is necessary to acknowledge an immediate contradiction in the context of a discussion of whether erosion is caused by large- or small-scale events. As anyone who knows the history of Hazelwood, knows the reserve used to be a freshwater marsh, but was made intertidal on 5^th/6^th December 2013, when a large storm surge, caused the embankment flood defences to breach, leading to a permanent inundation of sea water into Hazelwood marshes. Therefore, it could be said that it is case closed, it is the large-scale flood events that cause severe erosion.

But in the case of Hazelwood, since the storm surge breach in 2013, it could also be said it is the gradual, small actions of waves, that could be significant. When you walk along the raised path to the bird hide at Hazelwood, when the tide is coming in, there is a noticeable change as the tide water which has been silently creeping in begins lapping at the side of the bank below the path. It is this constant movement, the tiny incremental expressions of energy, that could be said to be nibbling away at the banks on the reserve.

Erosion on the side of path facing the estuary, on the way to bird hide at Hazelwood Marshes

In the last few months, Suffolk Wildlife Trust who manage the reserve have removed a line of dead blackthorn trees and scrub scoured by intertidal salt poisoning. The materials were removed so they could be used to help support the structure of the path to the bird hide and infill some eroded sections. Erosion of the grass banks at the back of the reserve, below the holiday property, Marsh View is also visible.

Scouring into grass bank at back of reserve at Hazelwood Marshes

It is also noticeable how high the tide line appears to be, continuing the discussion of whether it is significant high water or the gradual actions of waves, that is causing the most erosion at Hazelwood.

High Tide line at the top of eroded grass bank, at back of reserve at Hazelwood Marshes

At the open coast at Sudbourne Beach, it is a more complicated picture. The coast is currently separated by a narrow shingle ridge from the Alde & Ore estuary. On the first section of shingle ridge from the Martello Tower towards Orfordness, various flood defences are deployed, such as concrete mattresses, concrete blocks, and large boulders. However, beyond a certain point, the flood defences stop, and the shingle continues without further defences.

The processes of erosion are two-fold. Above the various flood defences, there is significant scouring into the top of the shingle path, making it quite narrow to walk on. Proof, if it were needed, that the North Sea has never had much respect for flood defences.

Erosion at top of Concrete Blocks deployed as Flood Defences on Sudbourne Beach, near Aldeburgh

However, on the section of shingle not protected by flood defences, the shingle ridge has been pushed quite far back and there is evidence of a recent breach at the top of the ridge that separates the beach from the Alde & Ore estuary. It is likely this breach occurred during the high tides in January and February 2022.

Breach in Shingle Ridge, separating open North Sea from Alde Ore Estuary, Sudbourne Beach

To consider the erosion at Hazelwood Marshes and Sudbourne Beach, it is useful to further develop the definition of erosion discussed above. Whilst it is clear that sediment is being removed from the specific areas discussed, it could be said there is also a process of altering, noticeable losses of solid structures.

Therefore, to conclude the second debate in this series, to consider whether erosion is caused by large scale or small processes, the conversation could simply be a discussion about stages of damage. The incremental continuous damage to coastal features or the sudden forceful visibly recognisable events that create a hole or a channel through a seemingly firm feature. Assessment of this damage, as a one-off specific occurrence, or the culmination of damaging processes, could frame an evaluation of the significance of erosion in vulnerable coastal areas.

Sudbourne Beach – an update

This piece seeks to provide a brief update to a previous piece on Sudbourne Beach, which is a shingle spit south of Aldeburgh on the Suffolk coast.

A public consultation was held between 1 October – 30 November 2019 regarding the policy of the Coastal Partnerships East and East Suffolk Council Shoreline Management Plan (SMP) in regards to Sudbourne beach. The consultation sought views on whether the policy of the SMP should maintain an interim position of No Active Intervention, after the current policy to Hold the Line expires in 2025. The alternative up for consultation, was a change of policy to Managed Retreat, which would seek to actively manage the rapidly eroding shoreline at Sudbourne Beach.

As the result of the public consultation the East Coast Council has now formally adopted a permanent policy of Managed Retreat, which will mean Managed Resilience of the Shingle shore, extended to 2100.

Recent reports from the Environment Agency state that as a result of winter storms, the ridge on Sudbourne Beach is changing daily. A reminder that the future of this fragile spit is bound up in the actions of the shifting ferocious tides and the authorities and concerned residents attempting to prevent the spit submitting to the erosive forces that threaten its future.

Sudbourne Beach situated south of the Martello Tower near Aldeburgh on the Suffolk coast is a shingle spit that separates the open coast from the Alde/Ore estuary. Recently, the sea has eroded the shingle spit at a greater rate than has previously been experienced.

Coastal Partnerships East and East Suffolk Council have a Shoreline Management Plan (SMP) which maintains a policy to Hold the Line up to 2025. This approach seeks to uphold or if necessary, add to and improve existing sea defences. These bodies also hold an interim position of No Active Intervention in the medium to long term, which would see no active investment in sea defences. However, concern about increased erosion has prompted these bodies to launch a public consultation to change the SMP position from No Active Intervention to Managed Realignment. A policy of Managed Realignment as defined by the Department for Environment, Food and Rural Affairs (DEFRA) means ‘allowing the shoreline to move backwards or forwards, with management to control or limit movement’. It is hoped this policy will enable maintenance of the ridge to prevent a permanent breach.

A Draft report, the SCF-130619-SMP7-Policy-Review-Slaughden undertaken by Jacobs Consultancy commissioned by East Suffolk council in partnership with a Client Steering Group, identifies the area of Sudbourne beach and Slaughden ridge as ORF15.1. This area begins at the termination of the concrete walls at the Martello Tower and extends southwards to Lantern Marshes. The open sea and the Alde/Ore Estuary exist as two distinct but linked elements, but the ORF15.1 shingle spit is very narrow, prompting fears of a breach at a future date.

As an indication of just how the state of ORF15.1 is constantly shifting, three photos show how quickly the sea can alter the beach and shingle bank. The first two photos are from the Draft SCF-130619-SMP7-Policy-Review-Slaughden. The first photo taken in July 2017 shows a substantial wide shingle mass on top of Slaughden Ridge.

The second photo taken in December 2018 shows a big reduction in the mass of shingle with a cliff formed of shingle on top of Slaughden ridge.

This later photo is similar to photos used again as a comparison by the Alde and Ore Association in their Spring 2019 newsletter. The first photo they use taken from above in December 2018 shows the steep shingle cliff with a wide section of shingle on the beach.

The second photo taken in January 2019, shows the sea has moved the shingle to the back of the beach raising it up to a much higher level. The shingle cliff looks much diminished from the December 2018 photo.

It is also worth considering from the point of view of wider consideration of coastal erosion in the Alde Ore Estuary that each feature involves distinct but connected alteration processes. Hazelwood marshes became an intertidal marshland following a storm surge that breached sea walls protecting the freshwater marsh.

Sudbourne beach and Slaughden ridge whilst processes are clearly not helped by storm surges, are subject to erosion caused by the regular attrition of changes in wave behaviour.

The next feature, Havergate Island could be said to be subject to both these processes, it has been struck by storm surges and regularly manages changing, escalating sea activity.

Alde/Ore Estuary

The Alde-Ore Estuary, of which Hazelwood marshes is an intertidal component, is long and thin with two main sections. The upper estuary, the Alde refers to the area between Snape and Halfway Reach, an area south of Slaughden next to the radio station below Lantern Marshes. The area of the estuary from Halfway Reach to the sea is referred to as the Ore.

Regarding the two sections of the Alde/Ore Estuary, there are features in each that are worth looking at closely regarding dynamic coastal changes with potential to alter nature reserves and landscapes. The first facing out to the sea, just up from Halfway Reach, is Sudbourne Beach. A rapidly eroding shingle spit, with concerns the sea could forge a permanent breach and enter the estuary landscape.

The second area is Havergate island, opposite the village of Orford. In 2018, the RSPB lowered the sea wall to manage storm surges to channel water into certain lagoons.

Each feature like Hazelwood Marshes is in a process of evolution with the sea shaping and remaking each area, with a constant risk forces could impose a permanent detrimental change. At the same time those keen on preserving each area wish to implement plans to retain the features long term physical presence in the estuary. To consider these processes in more detail each area will be discussed in detail starting with Sudbourne Beach.