Chichester District Council has advised residents and visitors to Selsey that a section of the sea wall will be closed will repairs take place.
A 'surface water outfall', which was installed by CDC in 1948, is set to be upgraded as a 'number of blockages' over the past five years which have resulted in surface water flooding of the car park.
The stretch between the public slipway and Honest Bills will be closed. Work will star in late October and will last for up to seven weeks.
Councillor John Connor, cabinet member for environment said: "Although we have made every attempt to minimise the impact of this work on the public, this section does need to be closed while the work takes place.
"The outfall desperately needs to be replaced in order to help protect properties for the future.
"We want to give people mas much warning of this work as possible and we would like to thanks the public in advance for their patience while this important work takes place."
Members of the public will be able to pass the closed section by walking behind the sea wall.
Engineers have said that flows from the outfall will be maintained throughout the works so there will be no impact on the existing drainage network.