Erosion to the Haslar sea wall in Gosport could lead to rapid silting – making Portsmouth Harbour inaccessible to large vessels like cruise ships and the navy’s two aircraft carriers.
The sea wall stretches along the south coast of the Gosport peninsula covering the former HMP Haslar and the southern flank of Fort Blockhouse – the sea wall makes up the western side of the harbour entrance.
Chris Donnithorne, a retired naval officer, has delved into the state of the wall and produced a detailed report in which he said Portsmouth Harbour was under greater threat than ever.
‘A breach of the seawall, leading to flooding in Gosport, and subsequent harbour silting remains a possibility, repairable at a cost,’ he said.
‘Potentially more dangerous, and a situation never before reached, is the undermining of the old fort itself, sitting as it is on a bank of sand and shingle.
‘Erosion and reduced tidal scour would potentially cause rapid silting, and hence loss of the deep water harbour.
‘The undermining process has started and could be catastrophic; the cost of re-establishing the harbour entrance would be eye-watering.
‘If we do not stop abusing Portsmouth Harbour, we will lose it.’
The Haslar sea wall is supervised by the Ministry of Defence – which says it is aware of the potential threat to naval operations.
An MoD spokesman told The News: ‘We are aware of the potential issue posed by storm damage and coastal erosion to the Haslar sea wall and are working with partner agencies to ensure there is no threat to the use of Portsmouth Harbour’
Wider government investment will see some £5.2bn spent on flood and coastal defences with £55m allocated to the Solent and South Downs.
Caroline Dinenage, Gosport MP, has spoken with minister for nature recovery and the domestic environment, Rebecca Pow and the Environment Agency about the state of the sea defence.
Ms Dinenage said: ‘The Gosport sea wall is the vital barrier which helps protect the integrity of Portsmouth Harbour.
‘Portsmouth Naval Base, the commercial port and hundreds of homes and businesses which surround the harbour depend upon it being kept in good condition.’
Ms Dinenage said the minister had taken her concerns ‘seriously’, asking officials at Defra and the Environment Agency to look into the situation,
She added: ‘I will be hosting a meeting with other agencies later this month to ensure there is a strong plan in place to see if the sea wall is properly maintained.’
Council leaders on either side of the harbour have expressed the importance of sea defences for safeguarding communities and maritime traffic.
Gerald Vernon-Jackson, leader of Portsmouth City Council said he was unaware of the potential threat Haslar has to the harbour.
‘We know that sea levels are rising, we know that the power of the waves in the Solent are getting stronger so they are able to punch holes in the sea defences where there are weaknesses in ways they couldn’t in the past,’ he said.
‘This will only get worse over the next 100 years so there is a need for investments in sea defences - most of them are very old.’
Councillor Graham Burgess, leader of Gosport Borough Council, said the sooner work is done to Haslar the better.
‘The latest gale took out a section of the large stone blocks and exposed voids underneath’; he added.