Photo: © Barry Culligan

The purpose of the groynes in St Francis Bay is to combat severe coastal erosion, to stabilise the shoreline and to safeguard properties and municipal infrastructure from ongoing storm damage. Spearheaded by the St Francis Property Owners Association (SFPO NPC), the project is part of the Long-Term Coastal Protection Scheme (LTCPS) to rebuild the area’s vanishing beaches.

The dunefields played an important role in maintaining sand levels at either end of the bypass. The westerly wind which is our prevailing wind, blew sand from the Oysterbay beach across the headland into St Francis Bay. This sand would replenish the beaches of St Francis. 

Human activity, such as building along the coastline, has led to the reduction of the dunefields and less sand reaches the bay. Compare the photo made in 1961 to the one below.

How will the Groynes work?

The groynes work through a combination of engineering design and environmental management:

• Trapping Sand and Interrupting Drift: The rock structures are built perpendicular or angled to the coast to intercept the relentless longshore drift. They slow down side currents, allowing sand to accumulate and settle on the up-drift side rather than being stripped away.

• Sand Nourishment: The groynes are designed to retain sand that is actively pumped and dredged via pipelines from the heavily silted Kromme River estuary. This dual action restores beach levels and protects the critical estuarine spit.

         Photo courtesy: SFPO

Beyond coastal protection, the trapped sand reshapes underwater sandbanks, creating new channels and wave lineups for swimming and surfing. Local surf trackers have noted that the structures help restore the beach breaks to historical conditions without negatively impacting the iconic nearby Bruces Beauties surf spot. 

Watch this Youtube video to see how the rock structures and dredging operations work together to restore the shoreline:

Dunefields now

What remains of the dunefields of St Francis is a 16 km stretch of magnificent beauty.