Sustainable sediment management research

Left unmanaged, natural sediment fills up port navigational infrastructure, impacting the depth necessary for safe loading, manoeuvring and transit of ships. A reduced ability to effectively load ships can have a substantial economic impact on the region that the port supports.

Learn more about how sediment affects our ports.

Great Barrier Reef World Heritage Area

We are the only port authority in the world to operate three ports in a World Heritage Area. It is a responsibility we take very seriously and we seek to lead sustainable port management.

Our innovative sediment management approach has been widely acknowledged and a similar framework is now applied in the Department of Transport and Main Road’s Maintenance Dredging Strategy for Great Barrier Reef World Heritage Area Ports. This is applicable to all ports operating in the Great Barrier Reef World Heritage Area.

Who was involved in our research?

We conducted the research with our terminal operators, Dalrymple Bay Coal Terminal and Hay Point Coal Terminal.

A Technical Advisory Consultative Committee (TACC) was formed, comprising representatives from the government, scientific and environmental organisations, businesses and the community.

How our research is different

A lot of previous sediment management research has focused on whether the sediment is clean of contaminants and where it can be safely disposed of.

Our sustainable sediment management study looked at this too, but also examined how and why sediment accumulates, and explored ways to reduce the build-up in navigational areas in the first place.

Additionally, we took steps to evaluate potential reuse of marine sediments. For each potential reuse or relocation option, we sought to demonstrate how environmental risks, human health, economics, and future challenges have been considered.

Five key objectives

Our research had five key objectives:

1. To understand the sedimentation profile at the port and what affect this has on port operations
2. To identify ‘what matters most’ to each of our stakeholder groups
3. To develop a range of options for managing sediment
4. To understand the performance of each option against the stakeholder priorities
5. To compare how each option balanced port prosperity with environmental, social and cultural values and select a preferred option.

What did we learn?

We now better understand how sediment moves at the Port of Hay Point. This enables us to forecast short- and long-term maintenance dredging requirements. It has also given us a robust and transparent method to define sediment disposal options.

More specifically, our findings include:

• As a port not located at the mouth of a river, the build-up of sediments at Hay Point is primarily caused by the natural movement of marine sediment along the nearshore coast due to currents and wave energy. Any sediment input from rivers is minimal.
• By 2016, approximately 200,000 m³ of sediment had accumulated in the port since we last conducted maintenance dredging.
• If this sediment is left unmanaged, it is probable approximately 200,000 m³ will accumulate every three years, under normal weather conditions.
• While maintenance dredging cannot be completely avoided, we can likely reduce the frequency of dredging to every five years in the future by making operational changes at the port.
• The effects of cyclones on sediment movement is unpredictable and can affect navigational areas in different ways. In 2010, Tropical Cyclone Ului had little effect on navigational depths, but in 2014, Tropical Cyclone Dylan resulted in large scale deepening in some areas of the port. On the other hand, in 2017, Tropical Cyclone Debbie caused approximately 150,000m³ of sediment to build-up at the port – mainly in the berth areas.
• There are limited opportunities for beneficial reuse of dredged maintenance material. While habitat restoration, particularly mangrove restoration, has potential merit, this approach will require investigation and further detailed studies. It may take more than three years before we determine if it is a feasible option.

Read more here.

Next steps

As of 23 January 2019, we now have the necessary permits to undertake maintenance dredging at the Port of Hay Point when needed, subject to weather events.

In December 2018, our advisory group of key scientific experts also met to continue work on a feasibility study into the beneficial reuse of dredged materials for habitat restoration or creation and how we might trial this option in the future. We are currently at Phase 2 of the feasibility works outlined here. NQBP has also committed formally to undertake this further work through signing an agreement with the Great Barrier Reef Marine Park Authority.