"Littoral drift generally moves from north to south, so the northern ends of bays are loaded with sand, leaving southern ends with a thinner beach profile and less of a barrier to incoming storms. This means our beaches aren't setup for constant storm action and sand gouging from the east to north-east."

You mean from south to north?

sorry for the nitpick, another great article.

can only seem to find archive charts back to '99 on the BOM site.

you know where to get earlier ones from Craig?

Sick.

I was looking at some swell diaries from 88/89 and what struck me was the amount of swell during summers of those years.

wanted to confirm observations by checking mslp charts.

Currently studying coastal engineering so pretty interested in studying the erosion patterns...
I wonder how well artificial reefs in problem areas (ie clarkes beach, belongil) would fare. Will be good to see the review of the palmy reef to see if they've seen lower levels of sand transport.
Coastlines are constantly being reshaped though and i feel like it's probably a bad idea to build a house too close to a sand beach.

Building houses on the dune system is a recipe for disaster for the tenants. Artificial reefs, if done properly may save some homes in danger but then impact others due to sand flows being disrupted. The only real option is retreat from the dune systems along the entire coastline. This will only become more common place due to sea level rise & the influence of climate change on the frequency of damaging storms( all of this driven by over population, check out Planet of the Humans on You Tube)! Cheers.

June 10 & 11 1994 - one of the biggest ever SW groundswells (lit up everywhere from Victoria and then up NSW coast) - checked the map generated for that date and it just looks like a long westerly fetch across the Bight. So the data is not that accurate or detailed enough for that type of system back then to be reproduced into a map that reflects the real situation.

Still it is an amazing resource.

Interesting read Craig,. Would you say the clustering of the systems occurs because the vacuum created by the onward movement of the last system allows a similar set of generation conditions for a new and similar system.

In La Niña scenarios without the westerly driver of El Niño is there more opportunity for this to happen?

I've often noticed a similar clustering in systems to the SE of NZ.

Of course strong El Niño seems to create endless clusters of flattened SW systems through the Southern ocean. It seems to me that La Niña allows for more weird and interesting weather events in our part of the world.

"But Risk Frontiers, a consultancy from Macquarie University, said the risks from the storms on assets such as coastal roads and property are being underestimated because they are typically treated as single events. Since east coast lows come in clusters, the impacts are magnified."

https://www.smh.com.au/environment/conservation/erosion-risks-underestimated-as-more-wild-weather-forecast-20200730-p55h43.html

Looking like another ECL/Tasman Low for next weekend.

That would be 1 every fortnight for 6 weeks.

Clusteroclock.

1990 & 1998 from memory were sick winters for swell as well

“Instead returning the land back to council and the rate payers in the form of a natural dune system is likely the smartest approach and arguably the cheapest in the long term.“

I agree with that idea, Craig. It was being looked at for our place over 20 years ago and I thought what a boon it would be for the local community, plus the people across the road would get a bonanza in terms of house price increases. But with the council owning the land (i.e. the ratepayers) council could terraform the land to both protect their roads and other properties as well as putting in protection measures for these big events.

Interestingly, at Norah head the beaches to the south that face south east were gouged out, and the beaches to the north that face north east we’re absolutely smashed. Especially to the north, it gouged out about 8 metres of dune that had been planted with what I think is the wrong type of grass, dunecare are helping the dunes and destroying the beach for surfers and swimmers. Banks there now are better than they have been for a long time.

Strangely, the beach at Cabbage Tree Bay, facing east and nor east but with various bombies around, has more sand on it than we have seen for years. I find myself lamenting that often when we think we are doing something good, the effects can be quite alarming down the track.

If I ever get off my arse I would like to bring this up with council. Interestingly one of the tracks to the beach further north, which has less sand build up and dune care activity had much less drop off and was in good nick. That area does protect some houses, but they are well back and not elevated in the way that Wamberal is. It’s a fascinating study, but from reading stuff on here and elsewhere I have come to the conclusion that dunecare that then leads to steep beach profiles is a disaster for users, and ends up more damaged during these cluster events.

Observations over a 25 year timespan.

Craig, I still think July 2011 will be hard to beat. Yes it wasn't 10ft, but with the LWT about as perfect as it could be for NSW, we ended up with two weeks of waves 3-6ft with westerly winds all day every day. I like the events that occur with west winds, as opposed to south winds where it's points n sheltered reefs only.

Love it Craig - another great piece! Any chance of producing a similar analysis centred around what impacts macro patterns in the southerns states of Vic, SA or WA?

Looks like there will be low pressure blanketing oz over the coming week. Wondering if this is La Nina related? Guessing there's gonna be some decent rain in some much needed places this coming week as well as some interesting little wave forming systems brewing sporadically.

the clustering effect is a key phenomena with flooding as well. An initial flood is normally at least partly absorbed by a river valley, with pools and wetlands filling, and groundwater being recharged. A second flood in a cluster is likely to do much more damage to infrastructure. And often requiring a lesser rainfall event.it's very interesting. Thx Swellenet

Wow, there’s the possible low off the NSW south coast next week Sunday/Monday (9th/10th Aug) but the long range models show yet another one the setting up the following weekend (15/16)!
Go the cluster!

A lot of South swell due for the East Coast of NZ over the next week or so. At least three different systems one after the other. I think these are the systems that also send swell up to the Southcoast NSW. Would be interesting to see the state of the long wave trough at the moment.