Configuration of Large-Scale Reef Components at a World-Class Surfing Break: Bingin Reef, Bali, Indonesia

Abstract

Bathymetric surveys of world-class surfing breaks have revealed large-scale reef components that holistically combine to produce high-quality surfing waves. Individual breaks are comprised of several of these components, or building blocks, often in recurring combinations that are linked by wave refraction. Here, 2-dimensional numerical wave refraction modelling is used to demonstrate the utility and connectivity of the specific combination of reef components at Bingin in Bali, Indonesia. Refraction modelling of the existing bathymetry at Bingin was in close agreement with field measurements and highlighted how the reef components function to produce consistent, high-quality waves. Wave breaking remained at a similar angle to the wave crest (-35degree) over a range of wave heights and directions in the main area of surfing. A defined take-off zone was a persistent feature, which is a result of wave-focusing over a large-scale reef component. Also very obvious in the model simulations, was the fast-breaking, steeper faced, part of the wave at Bingin, that is produced by a smaller scale reef component positioned on top of a larger feature. When the reef components that comprise Bingin were manipulated, and sometimes omitted, in most cases, the consequent changes to wave refraction produced waves that broke with less than world-class characteristics. The most common result was that waves broke too fast for surfing, or 'closed-out. In some cases this could be overcome be reorientating components at angles greater than those that exist at Bingin. However, this resulted in greater changes to peel angles with changing wave height and directions than normally experienced at Bingin. Re-positioning or omitting smaller reef components had less effect on wave breaking, but these changes still down-graded the quality of the wave for surfing.