To protect an estimated $1 billion worth of assets in Thames from flooding and rising sea level in the future, work on design concepts for a seawall is under way.
A seawall is a structure made of concrete, masonry or sheet piles which separate land and water areas, and protect land and property from storms, slips, rising tides and coastal erosion.
A governance group, chaired by Thames-Coromandel Mayor Len Salt, is progressing this coastal protection work as a priority with representatives from Ngāti Maru, Waikato Regional Council and Thames-Coromandel District Council.
A report received by the governance group stated coastal inundation and fluvial flooding had presented an extreme risk in the short to long term, “that need to be addressed to move forward”.
The first steps were the design for stopbank enhancement, combined flood modelling and financing while associated concerns include water supply storage, wastewater processing capacity and drainage systems, all needing to be enhanced.
Significant road improvements would also be required.
The community was consulted on the issues as part of the Shoreline Management project, which examined the risks to the entire Coromandel coastline from the effects of sea level rise.
A map from the Thames Spatial Plan indicates inundation risk in Thames.
Specific actions to manage those risks had been assessed and ranked, with work to protect Thames among the top priorities.
A public meeting where Royal HaskoningDHV will share the design concepts for the sea wall with residents and ratepayers in detail has been set up for later this month.
The design approach was to use barriers to prevent coastal flooding over the next 100-plus years, adapting in stages to a potential sea level rise of one metre.
The area of foreshore designated for protection runs from Hape Stream near the Toyota Factory to the Victoria Park/Croquet Club, with protection options including a mix of bunds, rock walls, and concrete vertical walls.
The default option was to build bunds with mild slopes and a wide crest, as they could be easily raised in the future.
In other sections of the foreshore, such as locations with space constraints, concrete walls could be needed.
Thames is facing a hefty bill to keep it dry from flooding.
Public feedback would be sought on the information presented at the public meeting, which included:
• Design options for each section of foreshore from Hape Stream and the Croquet Club
• Potential alignment options in each section.
• How the structures might tie in with the recreational facilities and environmental features that already exist along the foreshore.
Funding for the design work, and ensuing community consultation on design options, has been allocated through the 2023-2024 Long-Term Plan.
Funding for the construction of protection is yet to be determined but would likely require a mix of targeted rates and central agency contributions; any decisions on this would also require further community feedback.
The public meeting will take place on Monday, June 24 from 5pm in the Thames War Memorial Civic Centre.
