Short

Beach Surveying Beach, NSW, : 1976-2006

Andrew D. Short*

School of Geosciences, University of , NSW, Australia

In August 1975, I returned to Australia after 8 years in the USA to a marine science post-doc position at Macquarie University in Sydney. After having been involved in the famous SALIS beach project in Florida, been inspired by Sonu’s 3-D beach model (Sonu, 1973) and having monitored beaches along the Alaskan arctic coast (Short, 2020a), I was keen to see how higher energy rip- dominated beaches behaved. So, in April 1976, I set up a series of 14 profile lines along Sydney’s 3.6 km long Narrabeen beach. I also surveyed, sampled and mapped the entire embayment from a small boat using a sextant (horizontally), echo-sounder and pipe dredge (Figure 1). Beach surveying was undertaken with an assistant initially every 2 weeks using the Emery method (Emery, 1961). The equipment consisted of a notebook, 6 m pole, a survey staff, 50 m tape and set of fins. Each survey went from a fixed benchmark out across the beach and surf zone to ~3 m depth; hence, the 6 m pole and we walked the entire beach (Figure 2).

Figure 1. Narrabeen beach embayment surveyed with a very small boat, sextant and Raytheon echo-sounder showing location of the then 10 survey lines. (Source: Short, 1979b.)

DOI: 10.2112/JCR-SI101-020.1 *Corresponding author: [email protected] ©Coastal Education and Research Foundation, Inc. 2020

92 Journal of Coastal Research, Special Issue No. 101, 2020

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Figure 2. (a) Narrabeen beach surveys with Andy Short and 6 m surf pole in 1980. (b) Neil Trenaman, Andy Short and a young Ben Short in 1986, when we would swim out to 3 m depth. (Photos: A.D. Short.)

I soon found this was fairly onerous and after 3 months reduced the surveying to monthly (preferably at spring low tide during lower waves – in addition to immediately after storm events), then reduced the number of profiles to 10, then after six years (1982) to 5. In addition, surveys were taken immediately after any major storm erosion events (Figure 3). For the first 18 months (when I lived at neighbouring beach – I moved to Narrabeen in 1977), I also sketched the entire beach daily recording wave and surf conditions, location and shape of all bars and rip currents/channels, as well as conducting the offshore bathymetric (Figure 1) and sediment survey of the entire embayment. All of this resulted in a daily time-series of beach changes that led to the publication of the first wave-dominated beach model (version 1; Short, 1979a,b). Wright et al. (1979) published their version based on studies at Moruya (Bengello) Beach on the south coast of NSW. The two versions were integrated together with the results of a series of wide-ranging field experiments (Short 2020b) being integrated into the present Australian Beach State Model in Wright and Short (1984).

Figure 3. Narrabeen beach during Tropical Cyclone Colin (March 1976), which was located 500 km offshore and generated swell waves up to 10 m in height. (Photo: A.D. Short.)

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In 1989, after 13 years of surveying through surf and rips to beyond the breakers, I decided to stop the surveys at about 1 m depth owing to the fact that the surf zone tends to shift with the shoreline without major changes in morphology. All these cutbacks were a matter of balancing between either continuing or stopping the surveys altogether, and ultimately I decided it was better to compromise and continue. Finally, after 30 years of continuous monthly surveys recording the beach oscillating and rotating (Short and Trembanis, 2004), and with the help of more than 20 assistants, including my wife and my three children (we did live 50 m from the beach!), the last survey (#335) was finished on 24/8/06 and the ongoing responsibility for the program was then taken over by Ian Turner at the Water Research Laboratory of the University of (UNSW). Ian and his students and colleagues have continued the surveys using more sophisticated equipment and techniques (Harley et al., 2015; Figure 4). The end result is the longest whole-of-beach time series in the world, coupled with daily offshore waverider buoy, bathymetric, and detailed embayment and nearshore sediment data that are all freely available online (Turner et al., 2016).

During the 335 surveys, despite the often boisterous and rip-dominated surf zone, we had no incidents, no one got into trouble and no one had to be rescued. I would put this down to the fact we only had experienced surfers on the seaward-surf zone end of the transects. Along the southern Collaroy end, beach property boundaries, which included houses and then high-rises, were allowed to encroach onto the beach from the 1920s. This has resulted in ongoing problems for these properties with some lost to the sea in the 1940s and in 1967, with others making international headlines when hit by a major East Coast Low event in June 2016: (https://www.smh.com.au/environment/weather/sydney-storm-erosion-swallows-50-metres-of-collaroy- narrabeen-beaches-20160607-gpd2ob.html).

LITERATURE CITED Emery, K.O., 1961. A simple method of measuring beach profiles. Limnology and Oceanography, 6(1), 90-93.

Harley, M.D.; Turner, I.L.; Short, A.D.; Bracs, M.A.; Phillips, M.S.; Simmons, J.A., and Splinter, K., 2015. Four decades of coastal monitoring Narrabeen-Collaroy Beach: The past, present and future of this unique dataset. Proceedings of Australasian Coast & Ports Conference, Auckland, 6p.

Short, A.D., 1979a. Wave power and beach stages: A global model. Proceedings of the 17th International Conference on Coastal Engineering, Hamburg, Germany, ASCE, pp. 1145-1162.

Short, A.D., 1979b. Three-dimensional beach stage model. Journal of Geology, 87, 553-571.

Short, A.D., 2020a. Alaskan Arctic coastal fieldwork (1972-1973). Journal of Coastal Research, Special Issue No. 101, pp. 36-41.

Short, A.D., 2020b. Round and round Australia 1989-2001: 11,761 beaches. .Journal of Coastal Research, Special Issue No. 101, pp. 216-224.

Short, A.D. and Trembanis, A., 2004. Decadal scale patterns in beach oscillation and rotation Narrabeen Beach, Australia- time series, PCA and wavelet analysis. Journal of Coastal Research, 20(2), 523-532.

Sonu, C.J., 1973. Three-dimensional beach changes. Journal Geology, 81, 42-64.

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Turner, I.L.; Harley, M.D.; Short, A.D.; Simmons, J.A.; Bracs, M.A.; Phillips, M.S., and Splinter, K.D., 2016. A multi-decade dataset of monthly beach profile surveys and inshore wave forcing at Narrabeen, Australia. Scientific Data, 3:160024, doi: 10.1038/sdata.2016.24.

Wright, L.D.; Chappell, J.; Thom, B.G.; Bradshaw, M.P., and Cowell, P.J., 1979. Morphodynamics of reflective and dissipative beach and inshore systems, southeastern Australia. Marine Geology, 32, 105-140.

Wright, L.D. and Short, A.D., 1984. Morphodynamic variability of surf zones and beaches: A synthesis. Marine Geology, 56, 93-118.

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Figure 4. (a) The Emery method in operation. (b) Brad Morris and Andy Short on the 30th beach survey anniversary (27/4/2006). (c) left to right: Mitch Harley, Andy Short, Matthew Phillips, Joshua Simmons and Chris Drummond illustrating the range of increasingly sophisticated equipment used to survey Narrabeen beach (March 2015). (Photos: A.D. Short.)

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