Pagham coastal protection

The coast around England is typically managed by either the Environment Agency (EA) or the Local Authority. At Pagham, we manage the open coastline in front of the properties, whilst the EA maintains the defences inside and fronting the harbour. 

The EA has two main roles at Pagham:

• to be the Coastal Overview body. This role requires the EA to assess projects for their viability and to distribute the funding put aside by central government for flooding and erosion projects
• a a "permissive" maintainer of the inner harbour bunds. Under this role, a project was completed to improve the defences along the eastern part of the harbour to reduce flood risk to 88 properties at Pagham

Neither us nor the EA have a duty to protect the coast from erosion or flooding. The various Acts of Parliament under which we work provides powers to reduce the risk of erosion and similarly the EA to reduce the risk of flooding.

Natural England is the government's statutory adviser on the natural environment. They advise regulators such as us and the EA on issues related to wildlife and designated nature conservation sites. Natural England does not make decisions on coast protection or flood defence issues and is not responsible for undertaking coastal defence works. Their advice is sought when environmental interests might be affected, and this advice is taken into account when decisions are made.

The management of such a dynamic coastline as Pagham Beach has become increasingly difficult as conflicting interests such as socio-economic and environmental factors have become more influential.

We have followed the ‘Hold the Line’ Shoreline Management Plan policy however due to the dynamic nature, the Coastal Defence Strategy for Pagham beach has recommended an ‘Adaptive Management’ approach. Funding this option can only continue if future schemes remain economically viable.

Pagham Beach is made up of a dynamic shingle frontage and sandy clay lower foreshore that is unpredictable. West of the beach is the designated site of Pagham Harbour which has an impact on the natural development of the frontage. The upper foreshore is vegetated shingle and is a designated Site of Special Scientific Interest (SSSI). In addition, there are other environmental designations including a Special Protection Area (SPA), Ramsar and a Nature Reserve.

The history of flooding and erosion stretches back several decades. As of 2009, the frontage became increasingly subjected to erosion and scouring as the harbour realigned through the growth of Church Norton shingle spit. The alignment forced the harbour channel back towards the beach eroding tens of thousands of cubic metres of shingle.

The storms of 2013, 2014 and 2015 triggered losses of beach volume at West Front Road, placing properties at an increased risk of coastal erosion. The spit continued to grow and the focus of erosion moved.

Occasionally the crest width between properties and face of the beach was reduced in places to less than 10m and we carried out several emergency schemes in rapid response to the situation, including bolstering the beach to protect against coastal erosion. The 15 properties most at risk (to the west) are now protected by a rock revetment (see below).

The beach in front of a few properties immediately east of the most westerly groyne (Groyne 4) had been scoured following the growth of the spit and the partial collapse of that groyne.

In the winter of 2015/2016, the shingle spit was subjected to persistent overtopping followed by a full breach of the spit in April 2016 with the dominant channel migrating in a south westerly direction. This allowed the eastern end of the severed spit to weld onto the mainland, easing the scour current that had been persistently eroding the beach. The welded material now offers increased protection for properties on West Front Road.

Since 2016 the beach in front of East Front Road has been subjected to erosion. Crest widths have at times been reduced locally to less than 10m and we have carried out emergency shingle recycling schemes to protect properties there. 

It is impossible to predict future developments at Pagham Beach due to the changeable nature of the system. However, some very broad assessments have been made:

• developments may either close the harbour, potentially affecting the adjoining surface water drainage network
• open more fully, exposing the inner harbour to increased wave action, or;
• the Church Norton spit and associated delta and shingle bars may redevelop with similar or different effects to that which we have seen previously

Pagham Flood Defence Trust received planning approval to create a temporary outflow channel to reduce or avoid flood and erosion risk to properties and businesses in October 2021. This was possible after meeting the Imperative Reasons of Overriding Public Interest (IROPI) criteria and the ministerial decision from the Department for Levelling Up Housing and Communities (DLUHC). The scheme involved cutting a new outflow channel through the Church Norton Spit and providing compensatory habitat, forming a new tern island inside of the harbour.

The scheme sought to reset the position of the harbour mouth to a more hydraulically efficient position. The effectiveness and full outcomes of the scheme will only become apparent over time. The main benefit of the scheme is that it has reduced the short-term likelihood of flood and erosion risk and has enabled an extension of time for the site management decision makers. It is also expected that the severed section of spit will eventually join together with the beach face as was witnessed during the natural breach and re-distribution in 2016 to 2018.The reworking process from that breach is still ongoing and the volume of shingle released by the 2016 spit was far larger. We expect the nourishment benefit from the newly severed spit to be significantly smaller.

It is difficult to predict how long the harbour mouth will remain in the cut position as there numerous factors that contribute to the spit and channel evolution. Equally, the configuration of the spit and channel plays an important role on the likely impacts. This is well documented in recent history, where the spit grew naturally between 2003 to 2012 and had little to no effect on the properties at Pagham Beach. In contrast, following the natural reset in 2016, it was identified that the new course of the split had a higher likelihood of impacting properties, within a shorter timescale. The result of monitoring and discussion amongst the Pagham Coastal Issues Advisory Group was the 2021 managed breach scheme. It should therefore be understood that we have a limited dataset that documents a growth-to-impact period of 9 years and 5 years respectively.

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Following the breach of the Church Norton spit in 2016, the shingle mass migrated shoreward and eventually connected to the foreshore. Over time, erosion and scour followed its path east. As a result, restoration and emergency works were then necessary at East Front Road and in front of the Yacht Club. Since 2016, multiple shingle recycling schemes (of varying scales) have been completed in this area.

All beaches are monitored but, in line with the recommendations of the Pagham to East Head Coastal Defence Strategy in 2010, a further study was undertaken. This presented a number of ‘triggers’ which set out courses of action for various beach crest widths:

• 20 metres is a warning width when we would start monitoring the beach more frequently and begin discussing with the EA and Natural England ways forward.
• at 15 metres, we would take action by designing, seeking approval for, and putting in place, a flood and erosion risk management project
• if the beach crest reduced to 10 metres, we would begin emergency works to rebuild the beach width 

Before the natural breach of the Church Norton spit in 2016, some members of the community believed we should endeavour to ‘cut the spit’, to realign the harbour mouth and reduce the erosion at West Front Road. We were unable to progress this option due to time constraints, high costs and immature data to support the option. There was uncertainty that it would solve the problem in the longer term as we had not witnessed a natural breach and redistribution.

There were concerns that cutting a new channel through the spit was also likely to effect the harbour and the habitats which it supports. In turn these would require careful assessments as Pagham Harbour is of national and international environmental importance. The current central government framework of approvals and funding has therefore led us to follow the Adaptive Management recommendation as set out in the Pagham to East Head coastal defence strategy.

Pagham Parish Council submitted a planning application to ‘cut the spit’ in December 2015.  Following an 18 month process, planning permission was granted for the works in June 2017. However, following the 2016 breach and subsequent developments, the volumes and beach configurations at the time were such that the scheme was not viable within the conditions of the permission. The project is now being administered by Pagham Flood Defence Community Interest Company (PFDCIC). 

Whilst blocking the harbour mouth may have been technically more feasible and potentially cheaper than cutting the spit, actively closing Pagham Harbour presents several technical and environmental challenges. The harbour would cease to be tidal which presents a number of issues including that water would permanently cover most of the mudflats and saltmarsh. The scheme would alter the habitat as saltwater conditions would change to freshwater over time. There is also a risk that the barrier beach may breach, making it likely to reopen and therefore require further action. It is therefore believed that actively closing the harbour is not the right solution.

A revetment was installed in 2013 to protect the properties at highest risk of erosion (at the time) at West Front Road. When the construction took place there was an increase in scour to the area and we, along with the EA, believe that the revetment was key to the Pagham residents’ protection during the successive storms of winter 2013-2014 . Had the revetment not been in place, we would have lost many more metres of beach crest and probably several properties too.

We chose a rock revetment because the appraisal identified it as the ‘preferred option’ in accordance with the national flood and coastal erosion risk management grant in aid guidance. The option met the criteria set out by the project board, including;

• being cost effective
• being quick to put in place
• having minimal environmental impacts

Another benefit is that the structure can be dismantled and re-used elsewhere if conditions change to the point where it is no longer needed in Pagham.

Although the revetment was not specifically designed to combat the scour current that came after the erosion of the foreshore, the storms of 2013-2014 are thought to have contributed to the accelerated growth of the Church Norton spit which, in turn, changed the patterns of the currents in the harbour mouth. The structure proved effective during the severe weather of 2013 and 2014 winters. 

The cost of the initial construction of the revetment was approximately £500,000. Additional works included stabilisation of some of the rock and recycling shingle. The revetment is currently providing a 20 metre wide beach in front of the properties, which is typically sufficient to absorb wave energy and reduce overtopping to a 1 in 200 year standard of protection (0.5% chance of flooding in any year).

During 2014 and 2015, 6 schemes of shingle recycling were undertaken to increase protection to relevant areas of West Front Road. In addition, rock armour and shingle geobags were positioned to shore up two nearby groynes and sections of the revetment.

Historically, shingle was recycled from the near-shore shingle banks and placed along the Church Norton frontage, to help strengthen the southern spit. In 2003, the spit on the Church Norton side of the harbour started to accrete (grow) naturally. There was therefore no need to continue bolstering the spit and these activities were stopped. It is important to note that Pagham Harbour was not dredged.