Abstract

Narrabeen-Collaroy Beach, located on the Northern Beaches of Sydney along the Pacific coast of southeast Australia, is one of the longest continuously monitored beaches in the world. This paper provides an overview of the evolution and international scientific impact of this long-term beach monitoring program, from its humble beginnings over 40 years ago using the rod and tape measure Emery field survey method; to today, where the application of remote sensing data collection including drones, satellites and crowd-sourced smartphone images, are now core aspects of this continuing and much expanded monitoring effort. Commenced in 1976, surveying at this beach for the first 30 years focused on in-situ methods, whereby the growing database of monthly beach profile surveys informed the coastal science community about fundamental processes such as beach state evolution and the role of cross-shore and alongshore sediment transport in embayment morphodynamics. In the mid-2000s, continuous (hourly) video-based monitoring was the first application of routine remote sensing at the site, providing much greater spatial and temporal resolution over the traditional monthly surveys. This implementation of video as the first of a now rapidly expanding range of remote sensing tools and techniques also facilitated much wider access by the international research community to the continuing data collection program at Narrabeen-Collaroy. In the past decade the video-based data streams have formed the basis of deeper understanding into storm to multi-year response of the shoreline to changing wave conditions and also contributed to progress in the understanding of estuary entrance dynamics. More recently, ‘opportunistic’ remote sensing platforms such as surf cameras and smartphones have also been used for image-based shoreline data collection. Commencing in 2011, a significant new focus for the Narrabeen-Collaroy monitoring program shifted to include airborne lidar (and later Unmanned Aerial Vehicles (UAVs)), in an enhanced effort to quantify the morphological impacts of individual storm events, understand key drivers of erosion, and the placing of these observations within their broader regional context. A fixed continuous scanning lidar installed in 2014 again improved the spatial and temporal resolution of the remote-sensed data collection, providing new insight into swash dynamics and the often-overlooked processes of post-storm beach recovery. The use of satellite data that is now readily available to all coastal researchers via Google Earth Engine continues to expand the routine data collection program and provide key insight into multi-decadal shoreline variability. As new and expanding remote sensing technologies continue to emerge, a key lesson from the long-term monitoring at Narrabeen-Collaroy is the importance of a regular re-evaluation of what data is most needed to progress the science.

Highlights

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  • We focus on the Argus camera system developed by Professor Robert (Rob) Holman of the Coastal Imaging Laboratory at Oregon State University, aRsemthoitesSiesntsh. 2e01s8y,s1t0e,mx FtOhRatPEwEaRsRsEuVbIEsWequently adopted in Australia and much of the scientific litera9toufre25

  • At Narrabeen-Collaroy, today we pull in orders of magnitude more data in a single day than was obtained during the first decades when the monitoring program commenced more than 40 years ago

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Summary

Conclusions and Future

Based on more than 30 years of the combined Emery (pre-2005) and continuing RTK-GPS profile dataset, Harley et al [13] re-examined the initial PCA analyses [6,7] of embayment rotation at Narrabeen The use of this extended dataset and new analysis methods clearly identified that the observed shoreline variance and rotation at Narrabeen is dominated (60% of the total shoreline variance) by the cross-shore (rather than alongshore) movement of sediment, occurring at different magnitudes from north to south due to a distinctive wave exposure gradient along the embayment (Figure 4A). This focus within the international literature on the classification of characteristic beach states located along wave-dominated micro-tidal coasts was subsequently expanded by Masselink and Short [21], who introduction of the concept of a relative tide range to extend these same concepts to include macro-tidal coastlines

Developments in Video-Based Remote Sensing in the USA and Europe
Coastal Lagoon Entrance Sediment Dynamics
Shoreline Response to Storms
Shoreline Modeling
Shoreline Dynamics and the Role of Sandbars
Fixed Scanning Lidar
CoastSnap
Recent Developments
Airborne Lidar
Unmanned Aerial Vehicles
Findings
Conclusions and Future Directions
Full Text
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