Vulnerable parts of Ireland's most flood-prone city are to have their defences fast-tracked under an €80m tidal-defence scheme.

The Cork flood-relief project, whose cost is expected to spiral from €50m to around €80m, will begin construction next year but won't be fully completed until 2022.

It ranks as the single most ambitious flood-defence programme in Irish history.

However, in a major concession, the Office of Public Works (OPW) and Cork business chiefs are set to agree a deal whereby vulnerable parts of the city centre will have their defences prioritised as part of the overall scheme.

The OPW and Cork City Council have agreed that the Morrison's Island area - which has been subjected to five major bouts of flooding since 2009 - should have its relief works fast-tracked.

That is expected to offer greater protection for vulnerable parts of the city centre, including key trading areas, such as Oliver Plunkett Street, the South Mall, Winthrop Street and Pembroke Street.

It is now hoped that these flood-prone areas will have new defences in place within two years.

However, the full benefits of the OPW scheme won't be coming onstream until 2022 given the five-year construction period.

OPW Minister Seán Canney said he was confident that the scheme would deliver the protection that Cork requires.

He said: "The works will significantly reduce the frequency of tidal flooding."

Irish Independent