The Gold Coast is one of the most intensively managed and monitored stretches of coast in Australia. Since the early 1980’s there have been numerous successful nourishment programs taken place, which has enhanced the resilience of our beaches. One of the most notable was the introduction of the Tweed Sand Bypass program in 2001.
The project is a joint scheme between the NSW and Queensland Governments which was set up to establish and maintain a navigable entrance to the Tweed River and restore and maintain coastal sand supply to the southern Gold Coast beaches.
‘’Tweed Sand Bypassing consists of a 450m long fixed jetty system located at Letitia Spit, in northern NSW, and occasionally utilises a floating dredge. The eleven jet pumps located on the jetty create depressions in the seabed. As sand is moved along the seabed by coastal drift, it collects in these depressions, is captured by the system and pumped to a designated outlet. While there are four outlets, sand is predominantly pumped to Snapper Rocks East with pumping occurring overnight’’ (Source: coastalwatch.com)
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The southern end of the coast has long been known for its thriving surf culture and glorious banks and the introduction of the bypass program created the ultimate sandbar aka. The Superbank. It extends from the top of Snapper Rocks, through Rainbow Bay to Greenmount, and past Coolangatta Beach and Kirra. When the conditions are perfect people are said to have rides in excess of 2km.
Consistent monitoring and maintenance of beaches is a priority on the Gold Coast. They are the lifeblood of the city and need to be preserved so it remains a tourism, surfing and lifestyle hotspot for years to come.
Aerial Monitoring of Tweed Sand Bypassing Project
Aerial imagery of the project area is captured twice a year to assist in monitoring beach changes, particularly in response to seasonal fluctuations. Imagery covers the NSW north cost beaches between Kingscliff and Tweed Heads area, and the southern Queensland beaches from Point Danger to Burleigh Heads and extending to Kirra Reef offshore.
Project Challenges
The brief required imagery and mapping of the coastline at low tide, undertaken in the morning with the sun at a low angle to the east to minimise solar reflections on the water, and no cloud, fog or haze.
The first capture was completed in December 2017, however the cloud cover over the water created too much interference for reefs and other features to be clearly identified. Throughout the remainder of December 2017 through to early February 2018 a further 6 attempts had to be cancelled due to morning cloud cover.
In February 2018 the team got a clear morning at low-tide where they captured the coastline in high resolution imagery. The imagery was processed using photogrammetry to produce the beachline zero metre contour and 2.5m contour along the entire 25km stretch of beach from Kingscliff to Burleigh.
In addition a 3D mesh was also produced as a visualisation aid for the project.
Deliverables
- High resolution orthophoto imagery
- Contours along the beach (RL 0m & RL 2.5m)
- 3D pointcloud
For more information visit our Photogrammetry services page or call (07) 5631 8000
You may also be interested in: Coastal Mapping & Foreshore Monitoring for the Gold Coast
