Marine and coastal engineering is an ever-evolving field, blending human innovation with nature's dynamism. Among the myriad of techniques, sand bypassing and backpassing have transformed our approach to coastal management. Anchoring this transformation is International Coastal Management, led by the insightful Angus Jackson (quotes from his technical report).
Angus Jackson and Sand Bypassing
Angus Jackson’s words provide a glimpse into his rich journey: "I have been involved with the design and operation of sand bypassing systems during my time with City of Gold Coast as their coastal Engineer from 1981 and subsequently as founder and Chief Coastal Engineer of ICM, till present. My observations over these 42 years are as follows."
Some initial inspiration came when he ventured to the USA as part of a Gold Coast City Council tour in 1984, observing and learning from the coastal maestros of both the east and west coasts. One notable stop? The City of Oceanside, California, where Angus exchanged notes with fellow engineers on bypassing and beach nourishment. Lessons learnt were brought back, adjusted and implemented on the Gold Coast.
From the early trials on the Gold Coast to numerous successful implementations across Australia, Angus's commitment to understanding coastal dynamics has crafted a legacy in coastal engineering. His hands-on approach, buoyed by scientific rigor, has been instrumental in navigating the challenges of diverse coastal environments.
Decoding Sand Bypassing and Backpassing
Coastal currents, shaped by waves and tides, perpetually shift sand. Yet, human interventions, like jetties, can disrupt this flow, leading to imbalances. Angus elaborates on the solution: "The first fixed jetty mounted system, at the Nerang River entrance, was commissioned in 1986 to provide a safe navigable entrance and has provided proof of concept for permanent bypassing systems in high wave energy environments where dredging was difficult."
Bypassing and backpassing, therefore, are not just methods but crucial tools that maintain the ecological and aesthetic integrity of our shores. It really is a nature based solution approach to maintain natural sand flow.
Effective Sand Management
Delving deeper, Angus sheds light on the nuances of littoral transport: "Littoral transport of sediments (generally sand but can be shingles and other beach materials) is a result of the longshore currents generated by waves approaching the beach obliquely."
Understanding this transport is pivotal. As Angus points out, "Bypass systems are best suited to situations where there is a predominant net littoral sand transport in one direction and the flow of sand is interrupted causing sand deficit and erosion down drift."
Effective sand management, thus, involves recognizing these nuances and implementing solutions that are both efficient and ecologically sound. It is a vital piece of the puzzle when deriving coastal erosion solutions.
How Does Sand Bypassing Work?
In essence, sand bypassing is Mother Nature's conveyor belt, with a bit of human ingenuity. Coastal currents, driven by waves and tides, naturally shift sand. However, obstacles like jetties can interrupt this flow. Sand bypassing systems act like detour routes, mechanically transferring sand around these obstructions, ensuring that the natural movement isn't hindered. Think of it as creating a detour for sand when its usual path is blocked.
Advantages of Sand Bypassing
Erosion Control: With sand constantly on the move, areas down drift of obstructions can experience erosion. Sand bypassing counteracts this, maintaining beach width as a beach erosion prevention solution.
Navigation: For ports and harbours, sand can be a nuisance, leading to siltation. Bypassing ensures channels remain clear and navigable.
Recreation and Tourism: Ever visited a beach only to find it eroded? Bypassing systems ensure beaches remain tourist-friendly. They can also provided added benefits for improved surfing conditions as notably found on the Gold Coast in both bypassing locations.
Economic Benefits: From boosting tourism to reducing the costs associated with dredging, the economic perks are noteworthy.
Environmental Balance: Beaches are habitats too. Bypassing ensures minimal disruption to natural longshore processes, protecting coastal ecosystems by allowing natural flow
ICM's Bypassing and Backpassing Experience
Nerang River Bypassing and Backpassing
Angus Jackson, serving as the City of Gold Coast's coastal engineer, played a pivotal advisory role in the 1980s implementation of the Nerang River sand bypass system on the Gold Coast. This jetty-mounted pump system, established by the Qld Government, ensured safer navigation at the notorious Nerang River entrance, benefiting both recreational boaters and the commercial fishing fleet, while preserving natural sand transport patterns.
The fixed system places sand beyond the entrance and is complemented by a mobile dredge that clears sand build-ups in nearby channels. ICM has overseen several of these operations.
This effective system has not only boosted commercial and recreational marine activities, resulting in significant economic gains, but has also enhanced surfing, ensuring even naval vessels can safely access the Seaway.
Tweed River Bypass System
In 1985, Angus Jackson (Jackson 1985) pinpointed the need for a second sand bypassing system at the Gold Coast's southern end. Data revealed significant sand losses due to the Tweed River training walls since 1962, eroding southern beaches and leading to North Kirra SLSC being the only surf club without a beach.
Initiatives began in 1985, focusing on innovative nearshore nourishment to offset these sand losses and address rising sea levels. Research with the University of NSW confirmed the importance of restoring natural sand transport. By 2001, a bypass jetty was established, though occasional dredging remained necessary.
Crucially, dredged sand deposition was executed thoughtfully, enhancing a popular surfing location, creating the "superbank", and ensuring minimal beachgoer disruption.
Tallebudgera Creek and Currumbin Creek
The 1980s marked a transformative era for coastal management, especially around the Tallebudgera and Currumbin Creeks. These waterways, while picturesque, were grappling with challenges. Sand accumulation at their mouths disrupted the natural flow, heightened flood risks, and impacted water quality. But every challenge presents an opportunity for innovation, and that's where Angus stepped in with a visionary solution.
Angus recognized the multifaceted benefits of sand bypassing. By implementing annual pumping from these creeks, not only was the trapped sand effectively relocated to replenish the beaches, but two critical issues were simultaneously addressed: flood mitigation and water quality enhancement. The logic was simple yet profound. Removing excess sand would ensure smoother water flow, reducing the potential for floods. At the same time, with improved flow, water stagnation was minimized, leading to healthier, cleaner water in the creeks.
But how was this achieved? The tool of choice was a 12-14’ cutter suction dredge. This powerful equipment, designed to lift and transfer sediment, became the workhorse of the operation. Year after year, it has been put to task, ensuring that the sand bypassing process continues seamlessly.
Fast forward to today, and the legacy of that decision still resonates. The annual bypassing ritual has become a testament to foresight, innovation, and commitment to the environment. It's not just about moving sand; it's about sculpting a healthier, safer, and more vibrant coastal ecosystem.
Noosa Main Beach Backpassing System
Nestled in the heart of Queensland, Noosa stands as a beacon of coastal beauty, with its azure waters and golden sands beckoning visitors from around the world. But beneath this serene facade, like many coastlines, Noosa grappled with its own set of challenges. The preservation of its iconic Main Beach was paramount, and the need for an effective sand management system was evident.
Enter International Coastal Management (ICM). Leveraging decades of coastal engineering experience, ICM was approached to provide its expert insights on a proposed backpass system for Noosa. Designed by the renowned Slurry Systems, this innovative setup was poised to be a game-changer for Main Beach.
Backpassing, is a technique where sand is mechanically transported from areas of accumulation to areas of erosion, generally against the naturally net flow. It's one successful way to 'recycle' the sand in the system to prevent net loss.
ICM's role was multi-faceted. The first order of business was advising on the optimal location for the system. The placement was crucial, ensuring maximum efficiency while minimizing environmental impact. Next, ICM assisted in navigating the intricate maze of operations and obtaining the necessary approvals. With environmental and local concerns at the forefront, this phase was integral to ensure the system was not only effective but also harmonious with Noosa's natural and community landscape.
At its core, the backpass system's mission was clear: pump approximately 30,000 cubic meters of sand annually in a southward direction, rejuvenating and maintaining the splendor of Main Beach.
Today, thanks to collaborative efforts between ICM, Slurry Systems, and local stakeholders, Noosa's Main Beach continues to thrive, a testament to the power of innovation, expertise, and dedication to preserving nature's wonders.
Other Locations
Some other implementation dredge based bypassing systems by ICM include:
Rosslyn Bay Marina
Port Hacking
Scarborough Marina
Woorim
Runaway Bay Canal Entrance
Coffs Harbour
Mooloolaba River Entrance
ICM's Role in Harnessing Nature's Power
With Angus at its helm, ICM has consistently demonstrated an uncanny ability to harness nature's power for coastal management. Angus remarks on the versatility of bypassing systems: "Sand bypassing systems can be synchronous with the sand transport (such as a fixed pump system) or intermittent (such as by a mobile dredge that recovers sand 'lost' into a natural or man-made tidal entrance [e.g., a harbour])."
Furthermore, the benefits extend beyond mere coastal management. Angus notes, "With appropriate discharge locations, sand bypassing systems can improve surfing (e.g., Superbank) and provide substantial economic benefits."
Sand bypassing is a great tool in the coastal engineering toolbox that mimics natural conditions and work well in conjunction with nearshore nourishment and artificial reefs as proven on the Gold Coast, Australia.
Contact us about Sand Bypassing
With insights from Angus Jackson and ICM's unwavering commitment, our coastlines promise a resilient and vibrant future. As the sands shift, so does our approach, ever-evolving, always innovating.
Read more about sand bypassing systems and their impacts.