Coral reefs protect shores from heavy storms

April 13, 2018 Scientists investigated the protective function of the Ningaloo Reef during a hurricane

Coral reefs can protect coasts from tropical cyclones by reducing the impact of large waves before they reach the shore. Scientists from the ARC Center for Coral Reef Studies (Coral CoE) at the University of Western Australia have studied the impact of a tropical storm on the Ningaloo Reef in Western Australia.

Tropical cyclones cause devastating damage to coastal infrastructure, marine habitats and coastal populations worldwide. Dr. However, Michael Cuttler Coral CoE says a fringing reef can protect the beach from heavy erosion.

"Reefs can effectively protect shorelines because they can break waves off the coast, limiting the energy that affects the shoreline," Dr. Cuttler.

Dr. Cuttler and colleagues explored Ningaloo Reef - Australia's largest fringing system and United Nations World Heritage Site - during tropical cyclone "Olwyn" in 2015. "Olwyn" was a severe tropical cyclone of category 3 causing major damage to the coast of Western Australia.

The team observed that the coast remained largely unscathed due to protection from the offshore reef.

"The large waves generated by the cyclone were effectively dissipated by the offshore reef, and the low erosion was due to smaller waves generated by the wind in the lagoon," explains Dr. Cuttler.

The shape or geomorphology of the reef - with its steep pre-slope slope, shallow reef crest and relatively shallow lagoon - is representative of most fringing reefs worldwide.

"In this study, we also compared similar hurricanes on shores without reefs and found that these beaches were eroded up to ten times more than Ningaloo beach," Dr. Cuttler.

The results of the study by Dr. med. Cuttlers indicate that coral reefs can protect the coasts from tropical cyclones and other big wave influences.

Dr. Cuttler warns, however, that the ability of reefs to protect adjacent shorelines is threatened by both sea-level rise and deceleration of reef growth rates.

"These changes can ultimately increase the amount of wave energy that reaches the coast and potentially increase coastal erosion," says Cuttler.

So far, few studies have measured the hydrodynamic conditions and morphological responses of such a coast during a tropical cyclone.

Dr. Cuttler and his colleagues at Coral CoE say their results could be used to assess the dangers threatening coasts caused by extreme tropical cyclones. Damage to the coasts could increase in the future as climate change changes the state of coral reefs worldwide.

More Informationen: www.coralcoe.org.au.

Link to the Study: aslopubs.onlinelibrary.wiley.com/doi/abs/10.1002/lol2.10067.