Coastal Management - The Tweed River Entrance Sand Bypassing Project

Questions 1 - 9 page 167


Q1. Why did it become necessary to extend the Tweed River breakwaters?
The breakwater on the southern side of the Tweed River acted to trap sand that would naturally be moved in a northerly direction by longshore drift. The continual build‑up of sand on the southern side of the breakwater eventually caused the river mouth silt up and cause a blockage. 


Q2. 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 construction of breakwaters will cause the beaches on the Gold coast to loose sand due to longshore drift and the beach will be unable to naturally get their sand back, as it will but getting stuck at the river entrance.

Q 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 became unsafe for shipping because of sand bars building up in the River mouth making it shallow so the ships will run aground in the mouth so they had to stop shipping in the Tweed River. 


Q4. 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 coastal management as the barriers were not big enough so the sand built up over time and therefore had to rebuild them again. 


Q5. Describe the way the TRESBP replaces the natural process of longshore drift.
The TRESBP replaces the natural process known as longshore drift in the construction of breakwaters. This construction breaks the drift of the ocean when it hits the beach as it cannot go past the wall of rock.

Q6. 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 believe the TRESBP is one of the most successful projects in Australia for a few reasons. Firstly because the intended aim of the project was to stop silting at the mouth of the Tweed River and to stop the formation of a sand bar. 

The construction of breakwaters was the best thing that could have been done and did work in stopping the silting – temporarily. It gives developers an idea on what they should do the future, which may be even more beneficial and less costly.

Q7. Draw an annotated map to explain the operation of the TRESBP.

In the Book on page 167


Q8. Look at the aerial photographs in 7.28. Describe the changes that have occurred to the mouth of the Tweed River since 1962.
1962 – In this image it makes it very clear why the Tweed River mouth became a problem for silting up with sand, as the mouth is so open and unprotected from any thing it becomes very vulnerable to clogging up.


1969 – The construction of the breakwaters has opened the Tweed River heads and caused the beach to shift position. There is more sand on the surrounding beaches as the process of dredging has also taken place. however the river mouth looks alot cleaner and deeper therefore looks like it is working.


1994 – The breakwaters haven’t really changed but the amount of sand on the surrounding beaches has increased dramatically. Fairly soon a new solution will need to be put in place as the sand will reach the edge of the breakwater and will once again, begin to form a sandbar.


Q9. 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 the topographic map the length of the breakwater is approximately 350 metres in 1994.