Frequently asked questions
1. Why is the project needed?
2. How is the project managed?
3. How often does the system pump sand?
4. What environmental monitoring is undertaken on a regular basis?
5. Why are the southern Gold Coast beaches so wide?
6. Why can't the system stop pumping if people think that there is too much sand?
7. Why does the dredge keep coming back?
8. Is Kirra Reef buried forever?
9. What is happening at Duranbah Beach?
10. Is the Kirra Groyne going to be changed?
11. What is happening to Letitia Beach, south of the pumping jetty?
12. What will the Southern Gold Coast beaches look like in the future?
13. How far along the coastline does the project have an effect?
14. Why can't a pipeline be placed that would allow sand to be pumped past Kirra?
15. If the Tweed River Entrance is improved, why do entrance boating accidents still occur?
16. Why will the Southern Gold Coast beaches look more like they did in the 1960s?
17. What's happening with all the sand in Coolangatta Bay?
18. What impact did Tropical Cyclone Hamish have on the southern Gold Coast beaches?
19. Why was sand dredged last year delivered to areas offshore of Duranbah Beach instead of Snapper Rocks?
1. Why is the project needed?
- Prior to the Sand Bypassing Project, the natural northwards movement of sand from NSW to the southern Gold Coast beaches was prevented by the rock training walls at the entrance of the Tweed River. The walls had been extended in the 1960s and had the effect of trapping the sand. This resulted in severe erosion of the southern Gold Coast beaches. Eventually navigation through the Tweed River entrance was also badly affected.
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The Sand Bypassing Project overcame this problem by reinstating the northward movement of sand. This is done by pumping sand that is trapped south of the Tweed River, and discharging it beneath Point Danger, which is at the beginning of the southern Gold Coast beaches. Dredging using a floating dredge is also needed sometimes to clear sand from the Tweed River entrance.
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The benefit to Queensland is that the southern Gold Coast beaches will return generally to the way they were before the Tweed River rock walls were extended in the 1960s. For NSW, navigation through the Tweed River entrance is improved because only a small amount of sand moves into the river entrance.
2. How is the project managed?
- The Project is a joint initiative of the NSW and Queensland Governments and is administered by the NSW Land & Property Management Authority, and the Queensland Departmetn of Environment & Resource Management. The Project also receives funding from Gold Coast City Council and the management support of Tweed Shire Council.
3. How often does the system pump sand?
- The sand bypass pumping is a year-round operation to transport the sand that nature brings along the coast. The pumping system usually operates at night but on some occasions there is need to pump in the day. There is no ‘down period’ or ‘pumping season’ in the operation.
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One of the characteristics of the pumping system is that it is designed to replicate nature by transporting whatever sand nature brings along the coast to the jetty. Calm conditions usually means little or no sand to pump, while in higher wave conditions pumping may be continuous when there is a lot of sand moving along the coast.
4. What environmental monitoring is undertaken on a regular basis?
The project is monitored closely by the NSW and Queensland Governments. Three external environmental management system audits have been completed since 2001. The next audit will be in 2009.
- Monthly environmental monitoring summaries are produced for the project area between the Tweed River Entrance in NSW and Kirra in Queensland. Access the most recent summary on our Environmental management page.
- Beach profile surveys are undertaken quarterly between Letitia Spit in NSW and Kirra in Queensland.
- Additional beach profile surveys are undertaken annually out to twenty metres water depth between Fingal in NSW and Currumbin in Queensland.
- Wave conditions are continuously monitored by the Tweed, Gold Coast and Brisbane wave buoys, and this data is available through the Queensland Department of Environment & Resource Management website www.derm.qld.gov.au
- Aerial photography of the river entrance and the beaches from Fingal to Currumbin is undertaken every six months.
- Beach conditions are monitored continuously by a network of video cameras, and this information is available publicly through our Coastal video monitoring page.
5. Why are the southern Gold Coast beaches so wide?
- At the beginning of the project there was a need to transport large quantities of sand greater than the natural supply rate to ‘catch up’ and rebuild the badly eroded southern Gold Coast beaches.
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It was expected that the large ‘catch up’ sand quantities would disperse and spread along the southern Gold Coast beaches fairly quickly under the influence of seasonal and severe weather conditions. However there have been unusually calm weather conditions since the project started in 2000 and dispersal of the sand has not occurred as quickly as anticipated. The peak of the sand volume has moved along the coast from Rainbow Bay and is now moving through North Kirra.
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A large amount of sand has moved out of Coolangatta Bay and trends show that this will continue to happen (see FAQ 17).
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There is evidence that the sand mass at Kirra is beginning to disperse. Between July 2005 and July 2008 over 140,000 cubic metres of sand have moved northwards from the nearshore and offshore underwater parts of the beach between Kirra Point groyne and Miles Street groyne. This is a positive indication that the beachwill undergo the expected landward movement, or recession, that will lead to a narrower Kirra Beach.
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It is difficult to predict a time frame for the reduction in beach width as it is weather dependent. However one cyclonic event may be all that is needed.
6. Why can't the system stop pumping if people think there is too much sand?
- The Sand Bypassing System re-connects the Southern Gold Coast beaches to the natural drift of sand that moves north along the NSW coast and would otherwise be obstructed by the Tweed River entrance training walls. It does this for two main reasons: 1 - To provide the sand nourishment of the Southern Gold Coast beaches that was intended by nature; and 2 - To keep sand from drifting into the Tweed River entrance and affecting navigation by boats.
- The rate of sand delivery by the system mimics the estimated rate of natural sand transport at the time of pumping. Natural sand transport rates fluctuate seasonally and on a day to day basis. Sometimes nature supplies more than an average amount of sand, so this is the amount the system delivers. If a lesser amount were bypassed, sand would move past the jetty and enter the river channel. This would make access by boats into and out of the river entrance more dangerous. Also, the Southern Gold Coast beaches would not receive the sand they require to protect themselves against severe storm erosion for a long time if the sand was not transported to Pt Danger.
- The natural movement of sand northwards is happening day and night. In some northeasterly wave conditions sand may move southwards briefly, but the dominant direction of sand movement is northwards.
- The system has no ability to store sand or delay its delivery. It has a relatively small trap under the jetty formed by pumps that are located 12 to 15 m below the water surface. So, if nature brings sand into the jetty area it has to be transported away by the system or sand will move past the jetty into the river entrance. This limitation on trapping is typical of this type of bypassing system.
7. Why does the dredge keep coming back?
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The fixed sand bypass pumping system was designed to trap most of the natural northerly sand movement. However the pumping system will not catch all of the sand in all conditions, such as when there are large quantities of sand moving quickly. In these conditions some sand will move past the pumping system into the river entrance area and there is a need to periodically dredge the sand to remove it from the entrance.
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Dredging is of concern to some community members who feel dredged sand that is placed off Rainbow Bay only adds more sand to the large sand volume that is already moving slowly through the Greenmount to Kirra area. In response, the project is trialling ways of carrying out dredging so that this does not occur. This may be achievable by placing sand in some of the deeper nearshore areas where it will be mobilised only during larger storm events, that occur every few years.
Return to questions
8. Is Kirra Reef buried forever?
- Kirra Reef is largely covered by sand for the same reasons that Kirra Beach is very wide (see FAQ 5).
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As the volume of sand currently lying between Greenmount and Kirra disperses, the reefs will become more exposed.
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The reef should recover progressively from now on as the sand volume disperses.
9. What is happening at Duranbah Beach?
- Duranbah Beach is affected by the sand bypass project. This is mainly through the maintenance of a deeper river entrance by the project that means not as much sand moves across the entrance to nourish Duranbah Beach. Also the waves that come to Duranbah are changed slightly because there is now no river entrance sand bar. The result of these changes is that the beach is adjusting by moving generally landward as identified in the original environmental impact assessment.
- The project agreement between the governments provides for some 10% of the total sand volume to be discharged at Duranbah. Sand is pumped to Duranbah Beach according to a Duranbah Beach nourishment plan developed in association with Tweed Shire Council. The current approach is to make two sand placements each year (April and November) with allowance for emergency sand placements that may be needed after stormy conditions. While use of certain areas of the beach can be disrupted during placement operations, this approach has maintained reasonable beach amenity and good surfing conditions to date.
10. Is the Kirra Groyne going to be changed?
- The future of Kirra Groyne is a matter for the Gold Coast City Council which is currently undertaking a review study of all the Gold Coast beaches. The Gold Coast Shoreline Management Plan is a 3-year project which was commenced in 2005 with the aim to better understand and manage the Gold Coast beach environment from Point Danger to Currumbin. This study will assess and establish the future maintenance and works needs for each beach. The Kirra Groyne and its future will be considered in the study.
11. What is happening to Letitia Beach, south of the pumping jetty?
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The beach close to the pumping jetty has moved landward as an effect of the pumping operation. In fact the beach has moved about 90 metres landward from its position before pumping began in the area very close to the jetty and is now fairly stable. This local landward movement has spread southwards over time and tapers out smoothly along Letitia Beach to a point where there is no effect of the pumping system on the beach. Generally the effects of the pumping are confined to the beach area within one kilometre south of the pumping jetty. There is no effect at the Fingal end of the Spit, changes at Fingal Beach are a result of natural coastal processes.
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The re-alignment of the beach landwards has caused the loss of some of the older vegetation at the back of the beach at the north and centre of Letitia Spit. It is possible that more vegetation could be lost as a result of storm erosion from time to time. This vegetation will be collected and taken away.
12. What will the southern Gold Coast beaches look like in the future?
- When the wide beaches reduce in width, the southern Gold Coast beaches will generally look as they did prior to 1960. It was in the early 1960s that the rock walls at the Tweed River were extended and began to affect the sand supply to the southern Gold Coast beaches.
- Now that the large sand volumes of the first few years are dispersing, the project is now aiming to deliver only the quantities of sand that would have moved naturally. Therefore the beaches will generally cut and build in response to the swell conditions as nature intended.
- Access the TRESBP Environmental Impact Statement/Impact Assessment Study 1997 predictions for the southern Gold Coast beaches (PDF 23 kb)
13. How far along the coastline does the project have an effect?
- As at October 2006, the northern limit of beach rebuilding due to sand moved by the project is Bilinga and the project has no impacts north of this area at present.
- In the future sand will continue to disperse northwards to replenish the sand losses that have occurred over time along the Tugun and Currumbin beaches.
14. Why can’t a pipeline be placed that would allow sand to be pumped past Kirra?
The project has the aim of moving sand as nature intended. With the natural flow of sand onto the southern Gold Coast being by sand moving northwards around Snapper Rocks, the project mimics this by discharging sand immediately below Point Danger.
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The concept of a pipeline discharging further north has been raised in community discussion as a way of achieving narrower beaches in the Greenmount to Kirra area more quickly. Such a pipeline would require an elevated, highly visible and very strong structure to be erected on the beach running seawards from near Coolangatta Creek.
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The preparation of designs, planning documents, environmental impact assessments, and community consultation could take several years. Given that Kirra is showing signs of sand volume reduction as expected, by the time a new pipeline could be approved to build, the beach may have narrowed to a more ‘natural’ profile, and the pipeline would not be needed.
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In the “Kirra Wave Study” – Feb 2007 report prepared for GCCC, the estimated cost of the pipeline was given as $4.5 Million to build plus $0.9 Million per year to operate.
15. If the Tweed River Entrance is improved, why do entrance boating accidents still occur?
- Accidents at the entrance have occurred only very rarely since the Sand Bypassing Project has been operating. This is because the work largely prevents sand from building up into dangerous bars. Before the entrance was improved by the Project, accidents occurred quite regularly and these were often serious.
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Entrance accidents will still happen from time to time. However it must be remembered that the conditions of the sea at the entrance are not only determined by entrance depth and offshore wave conditions, but also the weather and river tidal flow, especially at times of strong outgoing tides. Skippers must always make their operations safe by correctly assessing the current and forecast sea conditions and be cautious in making a decision to use the entrance.
16. Why will the Southern Gold Coast beaches look more like they did in the 1960s?
- Extension of the Tweed River entrance training walls in the 1960s intercepted the natural northerly drift of sand along the NSW coast causing it to build up to the south of the training walls. This severely reduced the flow of sand to the Southern Gold Coast beaches. The Sand Bypassing System re-instates the natural drift of sand along the coast by trapping it and pumping it to Pt Danger.
- As the Southern Gold Coast beaches will now recieve the natural quantities of sand, these beaches will change and begin to look similar to the way they were before the training walls were extended in the 1960s. This is the reason the Project refers to the pre-1960s as the expected conditions of the beaches in future.
- Once beaches do reach a 'more 1960s' condition, they will still experience natural variations in sand supply, as all beaches do. One special feature of the Southern Gold Coast beaches is that they are subject to 'pulsing' in their sand supply because sand builds up south of Snapper Rocks and moves past Snapper Rocks in 'slugs' in response to episodes of increased southerly swell. This pulsing of sand supply is typical at headlands on the east coast of Australia.
17. What's happening with all the sand in Coolangatta Bay?
- During the early years of the Sand Bypassing Project, sand delivery rates were higher than natural sand transport rates (see FAQ 5). However, since 2006, sand delivery rates have reduced and they now closely match natural transport conditions. With less sand coming into Coolangatta Bay, the mass of sand in the bay has been able to disperse more rapidly under the action of natural waves and currents.
- Almost 500,000 m3 (or about one average year's worth) of sand moved out of the bay during 2007/08. Survey results show that this trend is continuing. About 80,000 m3 of this sand came from the Snapper Rocks/Pt Danger area and about 400,000 m3 came from the Rainbow Bay/Coolangatta area.
- The sand loss to date has occurred underwater. Therefore beach users will not have noticed any changes to the beaches as yet. However, over the next one to two years the dry parts of the beach are expected to become narrower and very much as they were before the 1960s. More information will soon be available on our Interesting items page.
18. What impact did Tropical Cyclone Hamish have on the southern Gold Coast beaches?
- Very little erosion was observed on the southern Gold Coast or the Tweed Coast beaches as a result of Tropical Cyclone Hamish, even though beach erosion was seen on the Sunshine Coast and beaches to the north of Noosa, which were much closer to the cyclonic cell.
- See graph of Kirra beach widths before and after Tropical Cyclone Hamish
- Tropical Cyclone Hamish did not travel far enough south for the Gold Coast to feel its full effects. Winds and waves generated by the cyclone had weakened significantly by the time they reached the southern Gold Coast beaches, and local wave heights only increased for about two days.
- The maximum wave height recorded on 11 March was 5.9 m, and the maximum significant wave height* recorded that day on was only about 3.8 m. A storm with waves of this size may hit the Gold Coast several times a year, so it was not a major storm or an unusual event.
- Given the direction of the swell, had the storm's duration been longer and had its waves on the Gold Coast been higher, then significant coastal erosion would most likely have occurred at Kirra Beach and other beaches of the southern Gold Coast. This would almost certainly have helped to accelerate the dispersion of sand from Coolangatta Bay.
- Longer lasting storms and high tides have occurred together many times before on the Gold Coast, often causing extensive erosion. An example was in 1974 when Tropical Cyclone Pam (maximum significant wave height of 3.8 m) coincided with a very high (spring) tide causing houses at Palm Beach to be flooded with sea water despite their protection by a 6m high boulder wall.
- *significant wave height (also referred to as Hsig or Hs) is the average of the highest 1/3 of waves occurring.
19. Why was sand dredged last year delivered to areas offshore of Duranbah Beach instead of Snapper Rocks?
- At the time of the dredging campaign in May-September 2008, there was still an excess of sand in Coolangatta Bay. This sand was being transported very slowly northwards by waves and currents. To reduce the infeed of more sand into Coolangatta Bay, it was decided to place most of the dredged sand offshore at Duranbah instead of the usual placement areas near Snapper Rocks.
- By placing sand off Duranbah, the sand has further to travel before reaching Coolangatta Bay. This would allow more time for the existing build up of sand in Coolangatta Bay to be dispersed naturally before receiving more sand.
- Much of the sand placed off Duranbah Beach was placed in deep water. The reason for this was to once again try and delay the sand movement into Coolangatta Bay. Deeper seabeds along the coast are generally more stable than shallower ones. They are less affected by the actions of nearshore waves and currents, so sand placed in deeper water tends to sit in one place for longer.
- Sand placed in deeper waters at Duranbah is not 'lost' to the beach system along the Southern Gold Coast; a more accurate way to think of it is that it is 'in storage'. Under sufficiently large storm waves the sand will be mobilised again and will eventually move into Coolangatta Bay. However, it could take some years for this to happen, as it depends on the occurrence of particularly severe storms.
- Between May and September 2008, 83,000 m3 of sand was placed in the areas marked as CNR-DBAH and ONR-DBAH on the Dredge placement area map. The outer nearshore placement area extends into water depths of up to 20 m below sea level. These are deeper waters than the project has placed sand in before.
- More information about TRESBP dredging is available on the Sand delivery page.
