Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Living coral reefs provide better protection from tsunami waves

20.12.2006
Healthy coral reefs provide their adjacent coasts with substantially more protection from destructive tsunami waves than do unhealthy or dead reefs, a Princeton University study suggests.

Initially spurred by the tsunami that devastated the coastlines of the Indian Ocean two years ago, a team of scientists developed the first-ever computer model of a tsunami strike against a reef-bounded shoreline, using a volcanic island as an example. The model demonstrates that healthy reefs offer the coast at least twice as much protection as dead reefs. The finding provides the first quantitative confirmation of a widely held theory regarding the value of living coral reefs as a defense against tsunami waves, which are often generated by powerful undersea earthquakes.

Princeton professor Michael Oppenheimer said his team's work will give scientists the ability to quantify how much any given reef will benefit its particular stretch of coast.

"Healthy reefs have rougher surfaces, which provide friction that slows the waves substantially in comparison with smoother, unhealthy ones," said Oppenheimer, the Albert G. Milbank Professor of Geosciences and International Affairs. "Scientists had never before studied this effect by the numbers, nor had they ever analyzed it over a wide variety of coastal shapes. This study provides yet another motivating factor for protecting the planet's coral reefs from degradation."

The team's findings appear in the Dec. 14 edition of the journal, Geophysical Review Letters. In addition to Oppenheimer, other team members include Robert Hallberg, who is head of the Oceans and Climate Group at the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Lab, and Catherine Kunkel, who is the paper's lead author. Kunkel spearheaded the work during her senior undergraduate year at Princeton, from which she graduated with a physics degree in June.

Though anecdotal observations of reefs' effects on tsunami abounded after the 2004 Indian Ocean strike, Kunkel said, it was difficult to form any real conclusions because so many of these observations came after the fact. The goal of this study, which began as Kunkel's senior thesis project, was to provide a systematic framework by which to examine the assumption that healthy reefs protect shorelines more effectively.

"For our purposes, we assumed that the health of the reef would only be important in terms of the drag it exerted on the wave," said Kunkel, who is currently working as a research assistant at Tsinghua University in China. "If you have a healthy reef, it has lots of live coral branching out, sticking a lot of small obstacles into the water. A dead reef, on the other hand, is not as rough -- it tends to erode and exerts less drag on the wave."

A turbulent mountain of water crashing over a complicated rough surface presented Kunkel with a number of obstacles for her own study -- specifically, how to find a way to express each of these effects with a mathematical formula that a computer could employ to simulate it. Different complex parameters had to be considered one by one: the width and depth of the reef; the roughness of its surface; the size of the lagoon behind it; and the slope of the coast beyond. And the overarching element was the wave itself and its interaction with all these obstacles. Eventually, Kunkel found a set of equations that provided a limited but comprehensive picture of a tsunami strike.

"We had to idealize a number of factors, because we wanted to create a model that could be used for a general shoreline," Kunkel said. "For example, we had to consider a perfectly even ocean floor, because uneven ones can funnel a wave into a certain area."

Despite the limitations of the model, Oppenheimer said it provides a sound basis for the team's conclusions.

"The general conclusion is that a healthy reef might provide twice as much protection as a dead one," he said. "This could translate into sparing large sections of inshore area from destruction."

Because coral reefs are dying from rising ocean temperatures, increasing ocean acidity, and direct human damage, Oppenheimer said the findings offer yet another reason to protect these fragile offshore ecosystems.

"This study shows yet another way that protecting the environment relates to humanity in a very tangible way," he said. "Villages get built behind coral reefs for good reasons, and this is one of them."

Kunkel said that she hoped the study would inspire other scientists to continue the research by obtaining more observational data. Incorporating such data into the team's theoretical model, she said, would then allow scientists to plan better for future tsunami strikes along local coastlines.

"We now have a basic idea of what variables are important, but if you want to quantify the effectiveness of a barrier reef around a particular island, you'd want to model that island directly," Kunkel said.

Abstract
Coral reefs reduce tsunami impact in model simulations
Catherine M. Kunkel, Robert W. Hallberg, and Michael Oppenheimer
Significant buffering of the impact of tsunamis by coral reefs is suggested by limited observations and some anecdotal reports, particularly following the 2004 Indian Ocean tsunami. Here we simulate tsunami run-up on idealized topographies in one and two dimensions using a nonlinear shallow water model and show that a sufficiently wide barrier reef within a meter or two of the surface reduces run-up on land on the order of 50 percent. We studied topographies representative of volcanic islands (islands with no continental shelf) but our conclusions may pertain to other topographies. Effectiveness depends on the amplitude and wavelength of the incident tsunami, as well as the geometry and health of the reef and the offshore distance of the reef. Reducing the threat to reefs from anthropogenic nutrients, sedimentation, fishing practices, channel building and global warming would help to protect some islands against tsunamis. Kunkel, Hallberg and M. Oppenheimer (2006), Coral reefs reduce tsunami impact in model simulations, Geophys. Res. Lett., 33, L23612, doi:10.1029/2006GL027892.

Chad Boutin | EurekAlert!
Further information:
http://www.princeton.edu

More articles from Ecology, The Environment and Conservation:

nachricht Value from wastewater
16.08.2017 | Hochschule Landshut

nachricht Species Richness – a false friend? Scientists want to improve biodiversity assessments
01.08.2017 | Carl von Ossietzky-Universität Oldenburg

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>