7.6 The Tweed River Entrance Sand Bypassing Project

1. Why did it become necessary to extend the Tweed River breakwaters?


It was necessary to extend the Tweed River breakwaters because the first breakwaters that were there were not doing the necessary job as should have been doing. More sand was building up and was becoming again an issue for the shipping industry.




2. What impact would the construction of the breakwaters have had on the replenishment of sand to the Gold Coast beaches after severe storm erosion?


The breakwaters would have diminished the replenishment of sand to the Gold Coast beaches because they were acting as a barrier to stop sand going into the entrance. With the breakwaters all there then the sand would not be able to move around as it would have done when the breakwaters were not there. The water then would only push the sand into the breakwaters and therefore not be able to replenish the sand at the beach.




3. Why did the Tweed River become unsafe to shipping? Explain the natural process that caused sandbars to form over the mouth of the Tweed River.


The Tweed River entrance had become unsafe to shipping due to the build up of sandbars along the entrance. This would diminish the depth of the water and make it dangerous for large ships to go through. The ships could potentially have scraped across the sand and could have become stuck. The natural process that caused this is longshore drift, the sand was being pushed in through the northerly direction. 




4. Why was the dredging of the Tweed River and the associated beach nourishment program only a short-term solution to coastal management of the area? 


It was only a short-term solution because the sand would once again go down the beaches because of longshore drift. The process would have to be repeated so that when the sand got to the entrance of the river it would have to be dredged back to the other beaches.




5 Describe the way the TRESBP replaces the natural process of longshore drift.


The TRESBP replaces the natural process of longshore drift by pumping the sand from where it accumulates on the southern side of the Tweed River via a system of pipes. The pipes go across the river to one of four outlets where it is decided which beach needs the sand and then it is released.




6 Write a paragraph that explains your opinion of the TRESBP. Why do you think the project is regarded as one of the most successful coastal management schemes in Australia?


I think that the TRESBP is very successful as it fixed the issues at hand. It was built on top of a idea that worked at the moment it was needed but in the long run it couldn't do the job. The TRESBP was big step up from the breakwaters that were applied and it is doing its job well. It does not keep the sand out but it does get rid of it straight away. This project definitely should be regarded as one of the most successful coastal management schemes in Australia.




8 Look at the aerial photographs in 7.28. Describe the changes that have occurred to the mouth of the Tweed River since 1962.


In 1962 when the first breakwaters were installed they were very small as not to look intrusive. This clearly wasn't doing the job so they were increased in 1969 by a long way. The new breakwaters were much larger and definitely looked out of place. These new breakwaters were still not completing their job as the sand was still an issue. So in 1994 the TRESBP was installed and has been doing a great job. It is a significant improvement to the 1962 and 1969 breakwaters.




9 Using the topographic map in 7.25 on page 164, estimate the length of the breakwater along the Tweed River entrance in 1962 and in 1994. 


In 1962 the breakwater was roughly 100m and in 1969 the breakwater was roughly 420m which is an  increase of 320m. This increase still couldn't to the job and to go any bigger would have made the beaches look horrible.