The evolution of Jumpinpin Inlet - OzCoasts

The evolution of Jumpinpin Inlet
Figure 9.1 is useful in highlighting times of expected beach erosion or accretion. It can
be seen that Jumpinpin experienced several periods of varying weather patterns:
(1) severe or very severe weather; (2) isolated incidents of catastrophic weather;
(3) incidents of catastrophic weather on top of severe weather; and (4) stages of fair
weather. Other factors in determining extent of damage are important, for example
the direction of cyclone approach. However, the most damaging weather occurs when
a catastrophic event manifests before and/or after a series of severe events.
This type of weather was seen in the 1890s. Four cyclones passed close to the area
in five years, only to be followed by three cyclones within the first three months of
1898 and severe weather in 1899. It is still difficult to determine when the spit at
Jumpinpin was first breached. In any case, the channel was given little reprieve to
repair the damage and close off.
The next catastrophic weather did not occur until the 1930s when a number of
cyclones affected the coast in quick succession: one severe cyclone in 1934 (when
the largest storm surge on record was measured), a catastrophic cyclone in 1936
responsible for breaching the Southport spit, followed by two very severe cyclones in
1938. It is believed that the 1936 storm was also responsible for creation of the
second channel at Jumpinpin.
In the late 1940s and 1950s the coast was once again battered. Very severe weather
preceded the catastrophic storms of 1951 and 1953. A reasonably isolated but
disastrous cyclone impacted the coast in 1967 to be followed by the great floods and
cyclones of 1972 through to 1976. Nineteen seventy-four was a significant year with
the largest peak wave height on record being taken. Several severe cyclones passed
in the early 1980s, followed by an isolated catastrophic cyclone in 1993 that closed
the Port of Brisbane.
From the data, a pattern of disastrous weather is observed roughly every
20–30 years. Analysis of the storm information provides likely dates for channel
breaching at 1898, 1911, 1936 and 1974.
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