Student 5: Low Achieved
Aim: Is Bream Bay in dynamic equilibrium?
Waipu Cove
Length
Height
0
0
25
1.05
45
2
66
2.90
78
4.35
90
7.1
94.5
6.54
A map and photographs completed the data.
Ruakaka Beach
Length
Height
0
0
20
0.75
32
1.5
42
2.29
54
3.55
68
6.05
76
5.2
[A]
Analysis
Beach profile: There is virtually no large berm, besides a relatively small one at the front or the dune
face. The beach profile is relatively wide and flat, rather than steep and narrow. This suggests that
neither constructive wave action nor long term destructive wave action has been occurring in the
recent past. A small amount of deposition seems to be occurring at the foredune with the small
berm.
Wave action: Both wave periods lead to the assumption that they are constructive waves. Waipu
Cove has a slightly higher wave height than Ruakaka, however, this is not clear enough to make a
conclusion.
Photo: the upper part of the dune here shows sand particles that have been swept up from the
beach from Aeolian forces accumulating on the windward side of the plants, aiding in dune
formation. This is some sort of evidence for dune building, rather than erosion.
[B]
Conclusion
My hypothesis/research question stated that the Bream Bay coastal environment was in dynamic
equilibrium. Before obtaining the data on a relatively fine day, the low pressure system that
dominated the east coast during the earlier weekend created stormy weather conditions. The
resulting waves would have been destructive and would significantly erode berms that would have
formed on the beach under the influence of constructive waves.
When waves break and swash rushes up the berm face, some water is normally lost by percolation
into the sand. Heavy rain associated with the depression may cause runoff from the land such that
the backwash is greater than swash, increasing erosion…
Waves are stronger and more concentrated at the headland. They attack the headland slowly
eroding the rock. The headland exists due to the harder rock that reduces the rate of erosion…
Longshore drift aids in the process of accretion through the interaction between waves, wind and
beach sediment…
Human factors were also discussed.
All these factors seem to support my research question that bream bay may be in constant dynamic
change, or is it in dynamic equilibrium.
[C]