May-June Storms 1974 Revisited

Fifty years ago in NSW we experienced a sequence of storms that for many of us constitutes the biggest storms on record in terms of impact. In this and a following blog I will recount some of that experience. It was fortunate that beginning in 1972 I started monitoring beach profile change north of the Moruya airport (Bengello Beach). Along with Roger McLean and others the profiles have been regularly surveyed: see a recent paper: “50 years of beach-foredune change on the southeastern coast of Australia: Bengello Beach, Moruya, NSW, 1972-2022”. Geomorphology, 26 July, 2023, https://doi.org/10.1016/j.geomorph.2023.108850 (with R. McLean, J. Shen, and T. Oliver). 1974 stands out in the story of this long-term commitment to understanding beach change.

Here I will offer some personal notes extracted from my diary commencing 24 May to 10 June 1974 noting that both Roger and I were based at ANU in Canberra at the time. In the next blog I will examine some of the implications of what we observed in the context of erosional events along this coast.

24 May: I did not have much hesitation today in cancelling our plans for the family to drive this weekend to the S.Coast. I checked Moruya Heads and Weather Bureau, and intuitive knowledge of weather patterns suggested a hellish time over the weekend. The question is how long will it last.

25 May: What a miserable day—strong persistent winds (in Canberra), periodic rain and cold. I didn’t venture outside all day and kept the kids inside.

26 May: The wild weather continued today. Winds from E & SE rushed across Canberra all day. I was disturbed at times and went out to look at the roof. Kids had to go outside in afternoon, they were going crazy; so were we. A low cell had developed off central NSW coast. High seas and winds were creating havoc along the coast. A 50000 ton tanker , the Synga, ran aground in Newcastle Bight. Lots of boats were smashed in Sydney and some people lost at sea in yachts. I wish I could see the action on the coast. Manly lost its pool on the Harbour side as waves entered the Heads and smashed against Harbour beaches.

27 May: Max Campion and Keith Fitchett (technical staff at ANU ) went to the coast first thing. They could not do the profiles but able to measure position of scarp and height and photograph effects. They reported spectacular retreats since last visit.

28 May: Rog could not contain himself. He had to go to the coast today and witness the change. He too was impressed saying he couldn’t recognise the place except that the stakes were present. The road near the airport has been severely cut. Most dramatically Broulee Island has lost its tombolo.

29 May: Rog and I travelled to Sydney in afternoon. Had arranged to meet Peter Roy for a look at beaches tomorrow.

30 May: Peter came before 8 and we took off for Cronulla. Saw an exposed peat bed on beach at east end of Bate Bay. Cronulla Beach was badly hit at south end—great scallops out of park behind what was the beach. Then onto Botany Bay and south side and north side surf beaches. Noted several things:

Inside harbours hit hard in certain places e.g. La Perouse, Balmoral, Manly. High setup in estuary.
Variation in energy levels today with some e.g. Maroubra, Curl Curl with + 3m waves, Bondi and Palm Beach smaller.
Beaches generally quite steep and straight (ramp) to cut dune (Dee Why, Palm Beach) or promenade.
Abundant sand blown or washed or spray transported across parks and parking lots and streets off beaches (e.g. Bondi, Bronte, Manly).
South end some beaches hit hardest (Cronulla, Avalon), whereas others at north end (Palm Beach). Newport knocked most where club house. Others like Bilgola cut along entire length and was most affected of the beaches with little sand left.
At Manly amazing amount of smashed boat debris, and my Dad (ex-Manly swimmer) would weep at the sight of destroyed pool.

Returned to Canberra in evening noting it was a “stimulating day”.

31 May: Off early to Moruya with Rog, his father Jack McLean, Keith, Max and Karl Shaw (another technical officer). The weather was gorgeous; we were fortunate, no breeze and the surf was moderate swell. Most dramatic changes since last survey. The scarp continues along the beach for the entire length. It has chopped back an enormous distance to within 1-3m of reference stakes in centre of beach. The beach is lowered to 1-2m. North of profile No. 4 the scarp has been overtopped and scalloped by return flow leading to a series of short gullies. The creek mouth (called Waldrons north of profile area) has been widened and here the scarp is highest. The entrance is partly choked with logs and finer organic debris. I’m amazed that the waves have chopped out the incipient foredune more-or-less completely. Returned to Canberra after surveying 7 profiles alternatively deciding who would take the staff into the water where current was strong in a channel.

6 June: Chatted with Roger about plans for a Coastal Engineering conference paper —we have to prepare a synopsis next week. He is keen to do a descriptive effort on Moruya observations. He had plotted out trends of different positions of profile No 3 over time. The result was startling as see beach width growing to June 1973 and from then to early 74 gradual erosion with accelerated loss in May 74. The winter of 73 onwards has had sea state conditions conducive to beach erosion not accretion. What is the cause of this trend? Karl and Max flew down to Moruya today to photograph the beach, the sea conditions were “quite rough”, but winds were slight.

8 June: Got cool and windy in Canberra in afternoon: part of fringe of a new Tasman Sea storm.

9 June: Another storm battering the coast with an intense cyclone in the Tasman Sea directing S-SE gale force winds. Seas rough to very rough carved into Cronulla as shown on TV removing the playground –so much for the artificial fill of 2 weeks ago. Alan Wilkie on TV tonight confirmed my suspicions about weather patterns and wave activity. From last winter on the coast has experienced more easterly air flow than usual and this he associates with general trend of anticyclones. As in 1950 this 73-74 pattern has been on a more southerly course. He believes this is due to higher Indian and west Pacific Ocean sea temperatures (3-4 degrees C) and expects these to weaken into 1975 due to cooling influence of the Southern Ocean (I put in brackets why?). I would like to get the temperature records of ocean and compare it with the position of highs for winter 1950-1974 and see what this looks like with respect to coast erosion: we may get a predictive pattern here. This could be quite exciting!

10 June: The storm continues to knock the coast. News on radio is that beaches south from Newcastle are badly hit e.g. Avoca, Terrigal, Bilgola (again!), Collaroy, Fairy Bower near Manly, Cronulla. Even south coast spots at Moruya (airstrip falling into the sea!) and Moruya surf club and Tathra have had their attention. Volunteers are working to save these clubs with sandbags.

Bruce Thom

Words by Prof Bruce Thom. Please respect the author’s thoughts and reference appropriately: (c) ACS, 2024. For correspondence about this blog post please email admin@australiancoastalsociety.org.au

#259