Beach changes along Kirra

Since 2002, there has been a build up of sand along the Kirra Beach to North Kirra Beach stretch of coast. This can be seen in the Tweed River Entrance Sand Bypassing Project's Kirra Point beach and Miles Street photo albums.

The sand build up has occurred during almost a decade of calmer than expected storm seasons. Especially notable during the 2000s has been the lack of ocean storms approaching from the North East, such as cyclones, which are the storms that generally cause the most significant coastal impacts along the southern Gold Coast. Large volumes of sand supplied by the sand bypassing system to rebuild severely depleted beaches in the early years of the TRESBP also contributed to the build up.

However, over the past few years sand dispersal has been occurring from the Kirra area and the sand build up has been reducing as sand is moved to the north by natural waves and currents.

Sand dispersal has been most rapid over the past year (2008/09), with the loss of more than 200,000 cubic metres of sand from the upper beach and offshore area between the Kirra Point groyne and the Miles Street groyne (July 2008 to August 2009). About 60,000 cubic metres of this sand was lost from the beach above the water line, and about 160,000 cubic metres was lost in shallow waters out to about 6 metres depth. Seabed levels in the nearshore area have also reduced by up to about 3 m and Kirra Reef has become more exposed than it has been in some time.

Preliminary results of October 2009 seabed mapping by the project show that the sand dispersal trend is continuing at Kirra Beach, with losses of a further 9,000 cubic metres from shallow waters between August and October 2009 (not shown on graph).

At Central Kirra between Miles Street groyne and Coolangatta Creek box culvert, sand dispersal has also been occurring, but so far it has been to a lesser extent that at Kirra Beach. Over the past year, almost 80,000 cubic metres of sand was lost from Central Kirra, mainly from below the water line (July 2008 to August 2009).

Preliminary results of October 2009 seabed mapping by the project show between August and October 2009, the upper beach in the Central Kirra area lost about 16,000 cubic metres of sand, whilst the nearshore gained about 16,000 cubic metres. This occurred as the upper beach adjusted to offshore erosion caused by the autumn 2009 storms. The result was that there was no net sand volume change at Central Kirra during these months.

The sand that has dispersed from Kirra and Central Kirra over the last few years has now reached the stretch of coast from the North Kirra Surf Clun to the Tugun Surf Club. There are no obstructive features such as headlands or groynes along this stretch of coast so the sand has been able to spread out more evenly instead of travelling as a large mass of the kind that has filled in the beaches from Rainbow Bay to North Kirra in the early years of TRESBP operations.

As a result of the spreading out of sand, the beaches to the north of the North Kirra shouldn't become as wide as the beaches from Rainbow Bay to North Kirra were in the early 2000s, but they will receive some much-needed nourishing sand.  

Click on the thumbnail above to view a larger version of the Change in Sand Levels Kirra Beach to North Kirra Beach July 2008-August 2009 diagram.

 (Sand dispersal from Coolangatta Bay is discussed on the Coolangatta Bay sand volumes page.)

Most of the sand dispersal from Kirra occurred during and after the autumn 2009 storms, particularly during and after the most severe storm of the season that occurred in May 2009. Rocks between the Kirra Point groyne and the Kirra Surf Club that had been covered by sand were seen for the first time in at least nine years soon after the May 2009 storm.

	May 2000 Although Kirra Beach had been nourished with 300,000 cubic metres of dredged sand in 1995, a large number of cyclones during the 1990s left Kirra in an eroded and vulnerable condition.
	October 2009 Fewer storms during the 2000s allowed nourishment sand to build up at Kirra Beach, though the autumn 2009 storms significantly reduced sand volumes and beach widths at Kirra.

Shoreline position monitoring carried out by the University of New South Wales on behalf of the TRESBP shows that the width of the beach in front of the Kirra Surf Club reduced by almost 100 metres from September 2008 to October 2009. Over the same period, at Central Kirra the beach width reduced by about 70 metres and at North Kirra there was very little change (about 15 metres reduction).

Most of the beach width reduction from Kirra to North Kirra occurred during May to July 2009, as the shoreline adjusted to nearshore storm erosion. A further 20 metres beach width reduction occurred at Kirra Beach following beach scraping works undertaken by Gold Coast City Council in July 2009, using part of the Queensland Government's $1.5 Million allocated funding for Kirra Beach improvement works.

Now that sand from Kirra and Central Kirra is dispersing and moving north, the beaches beyond North Kirra which have not been receiving a full natural longshore sand supply since the 1960s will gain sand. This sand will provide additional protection against storm erosion for these beaches.