Coastal Partners is a team of engineers, surveyors, project managers, environment and finance experts which manages the coastal flood and erosion risk across 162km of coastline.
And it comes as the coastal defences at Selsey are reviewed to see what work will be needed in the future to protect the area against flooding.
A spokesperson from Chichester District Council said: “We are currently reviewing our coastal defences in Selsey to identify the requirements for the years ahead and the costs associated with this.
"Once we have completed this work we will develop a detailed implementation plan and consult with our local communities in Selsey on any proposals.”
CDC’s cabinet member for the environment and Chichester contract services Penny Plant said the council’s new partnership came at a key time for the area.
She said: "The delivery of a resilient, professional, and cost-effective flood and erosion management service is becoming increasingly challenging in response to ageing defences, more extreme weather events and future sea level rise and the loss of experienced officers from the sector.
"By joining together with the other councils along our coastline we can combine expertise, local knowledge and access the most cost-effective solutions to protect our coastline and improve our local landscape. We can also continue to offer a robust and resilient service by sharing expertise and collaborating with other local authorities.
"One of the significant projects due to be delivered over the next few years will involve the coastal defences in Selsey, and so this is a great time to join the partnership. Projects such as this one will benefit from the involvement of a wide range of experts, enabling us to deliver the very best outcomes for our communities."
Lyall Cairns, executive head for Coastal Partnership, added: "We are looking forward to sharing knowledge and expertise to reduce flood and erosion risk to our shared community, while enhancing the environment for future generations to enjoy. We have a shared passion for our coastline and believe working together across five local authorities will deliver a high quality, resilient, and cost-effective service for our residents."