Farlington Marshes Project information page

Farlington marshes is protected by a 3.5km long coastal defence, which takes the form of an embankment with an armoured exposed face. The defence is split into four sections which represent a change in construction and material type. The defence sections are defined as follows:

• Section A: An embankment with concrete exposed face, natural crest and vegetated landward face.

• Section B: An embankment with concrete exposed face, concrete and sheet pile toe protection, concrete parapet wall, natural crest and vegetated landward face.

• Section C: An embankment with a concrete and gabion cage exposed face, natural crest and vegetated landward face.

• Section D: A natural vegetated embankment with gabions and informal rock armour protection on the exposed face.

The sea wall is in a poor condition and sections have been assessed as having a limited useful remaining life span. A significant breach of the sea wall could result in inundation of the Marshes and its terrestrial, freshwater and saline lagoon habitats, resulting in damage to and loss of the designated interest features of the site with subsequent knock-on impacts to important species and habitats in the wider Natural Sites Network.

Although there are low-lying homes within the wider coastal floodplain of which Farlington Marshes are a part, the existing sea wall does not directly provide protection to these.

(Image above) Condition survey sections

(Image above) Example of damage to existing revetment, 2019

With expert support from JBA Consulting & Volker Stevin, the project team are investigating options for the future flood risk management of Farlington Marshes.

Since spring 2019, engagement with key stakeholders including Portsmouth City Council, Natural England, Coastal Partners and the Hampshire and Isle of Wight Wildlife Trust has resulted in broad agreement that a Hold the Line (keep the current defence) strategy is the preferred management strategy for Farlington Marshes, at least until 2060. This is primarily due to the strategic importance of the site for its nature conservation interest and for public green space.

However it is accepted that, due to sea level rise projections, sea defence raising is not a permanent solution for the protection of habitats at this site and that therefore an opportunity exists under this scheme to start planning for transition to a more sustainable solution

Option selection for a solution at Farlington Marshes has focused on embodied and operational carbon dioxide emissions, with the aim of providing a solution that approximates net zero over its design life. When considering the net effect on greenhouse gas emissions of options, we are also considering the Marshes in their current state as a carbon sink.

Ground investigations were undertaken in 2022 and throughout 2023 we have been undertaking environmental surveys and modelling of the impact of different flood events as well as further research to help to inform the possible designs for improving the sea defence at Farlington Marshes.

In early 2024 we will be seeking planning permission from the local council to carry out our preffered option. Work is proposed to refurbish and strengthen the existing wall in order to safeguard the designated site and its ecological functions along with its current recreational and amenity value. 

This project aligns with Defra and Environment Agency policy on flood risk management as set out in the National Flood and Coastal Erosion Risk Management Strategy for England (2011), in particular in the strategy’s reference to the powers provided in the Flood and Water Management Act (2010) to manage flooding or coastal erosion in the interests of nature conservation.

Funding More Information

Any scheme must meet strict funding rules. This means there is no guarantee a future scheme here would secure funding from the UK Government. Funding from other organisations, along with potential funding from the Government, is likely to be required. It is also possible that no scheme goes ahead if the costs cannot be justified against how much benefit a scheme would bring.