A small wave peak, shaping up over a stone ramp, sand veneer above the high tide line
East coast Australian surf spots; beachbreaks, sand-bottom-pointbreaks,reefs, cliff-side-boulder-fields, platforms, ramps, bombora-controlled-beachbreaks...
You ride waves, but what are you surfing over?
What's on the seafloor at your favourite surf spot?
There are 226 recognised surfing reefbreaks on the east coast of Australia. The majority of these reefs, 72% are located between Port Stephens and Durras, a coastline dominated by sandstone. Geologists call it the Sydney Basin.
The state of New South Wales (NSW) has 721 beaches, many are popular with surfers. Less well known is that 26 popular surfing beaches are located inshore of deep water reefs, locally known as a bombora's (or 'bombies'). Examples of 'bombora controlled beachbreakss' include; North Narrabeen, Merewether, Woonona, Booti Booti, Old Bar, Pelicans, North Narrawallee and Conjo.
photo courtesy Mark Garnett
East coast beachbreak, 'corner ends' are popular with surfers for three reasons;
1.) lee of headland offers shelter from winds, providing smoother water
2.) topographic and headland-controlled-rips create semi-permanent deep channels providing reliable and easy access routes into the line-up
3.) rips, particularly mega-rips, deposit sand well seaward of the beach, providing sand banks more conducive to surfing
photo courtesy www.markgarnett.info/
East coast reefbreak: sandstone bedrock, series of terraced platforms, steep slope = quick breaking waves, visible creases in the wave face.
East coast reefbreak: boulder field, defining the edge between (sandstone) 'cliff-side debri' and 'headland-controlled-rip' on sandy beachbreak.
'Pete's Reef', igneous outcrops off sandy beach, east coast Australia's 'smallest' reef? Soundings and bathymetric interpretation by Andrew Pitt, air photo courtesy google earth,
Pete's Reef, 3D interpretation
Pete's Reef, waist high and 'touching bottom'....
Bombora controlled beachbreaks
'The Peak', a bombora controlled beach (note dark blue colour of reef) photo Google Earth
'Bombora controlled beachbreaks' are popular with surfers because:
1.) 'certainty', the bombora's focus advancing waves to a more certain location on the beach,establishing a regular ‘take off zone’
2.) ‘swell magnet’, through wave amplification, wave height is larger by a factor of 1.25 to 2, depending on wave period and swell angle
3.) ‘length of ride’, a wave is more likely to break as a ‘peak’ (rather than a‘closeout’) and therefore offer a longer length of ride
4.) 'easy access', bombora/topographic-controlled-rips create semi-permanent deep channels, providing reliable and easy access routes into the line-up
5.) ‘safety’, most surfing action takes place over a sand foundation, the deep outer reefs are rarely surfed, except on days with extra large waves, it is safer to wipeout on sand rather than reef.
Inshore of the bombora, sand tends to naturally accumulate in the lee of the reef/bombora creating a noticeable beach salient - a 'bend', 'corner' or 'elbow' in the shoreline.
For more information, download an 871kb pdf of a 12page paper - 'Surfing at bombora controlled beaches' - presented at The 5th Western Australian State Coastal Conference, Fremantle, October 2009. Or a 2 page 448kb pdf Bombora controlled beachbreaks presented at the 7th International Surfing Reef Symposium 2010.
Bombora controlled beachbreak: screaming lefthander!!! photo courtesy Steve
by Andrew Pitt © 2012