WALK along beach towards the seal colony at Horsey and you will encounter a series of huge stone structures stretching out towards the sea.

Visitors often ask us what they are and what they do. They have been built using  24,000 tonnes of rock imported from Norway for a £2m Environment Agency project to improve the sea defences between Winterton and Sea Palling.

Much of the work had to be done during a six-week window of opportunity when rare the Little Terns, who nest on the beach, were wintering in Africa. But it happened too be during the pupping season, so measures were put in place to minimise the disturbance to the hundreds of grey seals who come ashore there to give birth.

Peter Ansell from Friends of Horsey Seals said: “Currently the seals prefer to rest in the areas around the rock groynes already built, where sand levels are high. We hope that the new groynes will provide additional shelter and attract many more seals and tourists alike.”

Over a dozen new groynes have been constructed. According to the Environment Agency they are needed to replace the old timber and steel ones that have come to the end of their useful life.

The defences are vital to protect thousands of acres of agricultural land, businesses and homes from flooding. 

In 1953 a storm surge burst through the defences at Sea Palling, leading to the deaths of seven people. Much of the East Coast was devastated by flooding that night. The following year work started on a sea wall and you can still see section of this as you walk up the beach towards Horsey.

The low-lying broads near to Winterton and the dunes - a nature reserve and a site of special scientific interest - are protected also by the wall, which is itself protected by groynes. 

Ironically, an Environment Agency Coastal Trends Report  explains that defences further north at Cromer and Happisburgh have prevented sediment that would have been eroded from the cliffs there being washed down the coast and replenishing the beaches around Winterton.

Local geographer Pat Clarke explained how the groynes work.

“If waves are driven by the prevailing winds to approach the shore obliquely, sand is washed up the beach obliquely, but it returns straight down the beach. This causes the sand to follow a zigzag course moving it south along the coast,” she said. “The beach is the first  of delinefence and needs to be retained to protect the dunes.”

“Wooden groynes are sometimes used to keep the sand drifting south, but rock groynes are more common today. These may gradually be covered by the sand, but this means they are doing their job. The dunes are therefore protected by accumulated sand and are anchored by the long rooted marram grass.”

But she has a warning: “If paths over the dunes are over used then the dunes themselves will be lowered. Where possible try to follow designated routes on to the beach.”