COASTAL EROSION – MANAGEMENT AND MAINTENANCE – BEACH NOURISHMENT AND SEAWALL RECOMMENDATIONS

The primary objective of this Long-term Concept Design was to enable the City of Onkaparinga to proactively plan for erosion management of this popular beach between Witton Bluff North and the O’Sullivan Beach Boat Ramp.

Coastal Engineering Solutions developed a long-term strategy to achieve the joint objectives of protecting essential coastal infrastructure and maintaining the amenity of the beach.

These outcomes were successfully achieved by:

• investigating and addressing the underlying causes of shoreline erosion and its likely future progression at the local scale. It is only with this understanding that strategies can be applied with the confidence that they will not inadvertently exacerbate existing erosion problems;
• identify cost effective and sustainable erosion management strategies that maintain natural coastal processes and resources; and
• considering community needs in both the short- and long-term.

The recommended future management of the Christies Beach shoreline consisted of:

• upgrading existing seawalls – to provide robust protection to foreshore infrastructure during severe storm events.
• initial beach nourishment – placing additional sand on the existing foreshore to provide an appropriate beach amenity.
• sand management – maintaining the initially created beach amenity by on-going regular sand placement; transitioning in future years to sand retention measures in conjunction with back-passing.
• beach monitoring surveys – instigating a regular program of foreshore surveys to monitor future shoreline response as climate change influences emerge; and to guide future action.

Project by Coastal Engineering Solutions, now a part of Water Technology.