Inverloch inundation risk 'low' but not so erosion

THE first of the key reports on how to protect the beach, dunes, roads and houses at Inverloch from the march of erosion, and temporary or permanent inundation by the sea, came out last Wednesday, October 12.

A new, 1km-long seawall, stretching from the end of the existing rock wall at the Inverloch Surf Beach to Flat Rocks and a 145-metre breakwater, located 150m to 200m off the main surf beach at Inverloch are among the hard engineering solutions proposed.

Where the breakwater is concerned, the report authors acknowledge that it may not be popular with beachgoers because: “Surfing and beach use would be impacted by reduced wave energy.”

Relocating Cape Paterson-Inverloch Road (Bunurong Road) and a “planned retreat” from impacted areas are also canvassed.

However, notwithstanding the level of urgency in the Bass Coast ‘Mayor’s Message’ this week, where he calls on the State Government to fund research into a coastal erosion and inundation overlay, there’s no need to press the panic button just yet.

According to the reports, the risk of permanent inundation by the sea at Inverloch remains “low” out until 2100 in five of the six specific study areas in the town, the exception being the “Inverloch Foreshore Holiday Park to Screw Creek” area where “permanent inundation risks are low at present day, increasing to medium from 2040 to 2070, then significant after 2100”.

At the following locations, the risk of permanent inundation remains “low” to 2100:

* Flat Rocks to Wreck Creek (Bunurong Road)

* Inverloch Surf Beach

* Coastal Reserve (inlet entrance to The Glade)

* Inverloch Boat Ramp

* Inverloch Foreshore Dog Beach

However, the report finds that the dominant threat to Inverloch comes from erosion of the surf beach and dunes system, especially in the Wreck Creek to Flat Rocks area and along parts of Surf Parade. It reports the following:

* Inverloch Surf Beach: Erosion risks medium to 2040, then increasing to significant in 2070 and high at 2100. Temporary inundation risks are low at present day increasing to medium at 2040 to 2100.

* Flat Rocks to Wreck Creek (Bunurong Road): Erosion risks medium to 2040, then increasing to significant in 2070 and 2100. Temporary inundation risks are medium out to 2100.

The Cape-to-Cape Resilience Project Stage 1 reports, which comprise seven coastal hazard reports of 776 pages and a further six response reports, totalling 268 pages, focus attention on Inverloch but do start to address issues along the whole coast between Cape Paterson and Cape Liptrap.

While the reports paint a concerning picture for a limited number of locations in Inverloch, there’s a more positive outlook for other parts of Bass Coast and South Gippsland.

For example, while the reports say that the tidal levees within Anderson Inlet “are unlikely to be enough to prevent flooding during combined future coastal and catchment extreme flood events” over the next century, “the major residential areas within the inlet at Tarwin Lower and Venus Bay are almost completely above the predicted coastal inundation extents for all scenarios assessed”.

The reports found that the town of Inverloch is “mostly above the coastal inundation extent”, with the exception of areas around Wreck Creek and the Surf Beach residential area, around the boat ramp and jetty, and around the Screw Creek and Broadbeach Estate, “the area around Wreck Creek is considered to be particularly vulnerable due to the recent erosion of the barrier dune”.

“This dune currently limits direct coastal inundation of Wreck Creek and the residential area between Bunurong Road and the Surf Life Saving Club.”

A range of engineering solutions have been proposed, although not specifically recommended or costed, all with positives and negatives, and there are likely to be planning controls to follow, potentially even orders to vacate certain areas, limiting exposure to present-day and future risks.

The lengthy and technically complex reports were released more than two months after they were promised, leaving little time to lobby political parties for funding commitments ahead of the November 26 state election.

Some of the measures proposed in the report will need annual allocations of significant maintenance funding as well as major capital works funding if rock walls, breakwaters and groynes are to be part of the solution.

South Gippsland Conservation Society representative on the Cape-to-Cape stakeholders reference group, Philip Heath said his group welcomed the report but was disappointed it didn't provide recommendations on preferred actions.

"The fact that the study group hasn't provided recommendations indicates it will have to go through another process. None of the proposals have been costed either which makes it tough to get commitments from the political parties and candidates.

"We're encouraged that a number of the proposals include dune nourishment works but we would like to see some of that work going ahead sooner rather than later, while we wait for a plan to be formulated.

"The work that Parks Victoria has carried out on either side of the rock wall has been excellent and we'd like to see more of that.
"A lot of the erosion and damage to the beach and dunes has been caused by the combination of south-westerly storms and high tides and while that has slowed a bit in recent times, after more easterlies in the past year, we're concerned this has only delayed what is an ongoing situation.
"We're still losing mature coastal banksias at Flat Rocks. We need to be taking action to at least save those trees as the only thing protecting Cape Paterson-Inverloch Road."
Mr Heath said he personally saw merit in the proposal to construct a long groyne, up to 1/2km out into the sea from Norman Point, but the project team has listed a large number of "negatives" including complexity of construction and the need for an on-going investment in dune nourishment.
He said the South Gippsland Conservation Society would develop a comprehensive response to the report, with its own priority suggestions.