Scientists from the USGS and the School of Ocean and Earth Science and Technology (SOEST) at UH studied more than 150 miles of island coastline (essentially every beach) and found the average rate of coastal change – taking into account beaches that are both eroding and accreting – was 0.4 feet of erosion per year from the early 1900s to 2000s. Of those beaches eroding, the most extreme case was nearly 6 feet per year near Kualoa Point, East O'ahu.
The shoreline along Makapuu Point, Oahu, Hawaii, was included in the study released today.
Credit: Brad Romine, University of Hawaii Sea Grant/ Hawaii Department of Land and Natural Resources
"The inevitable fate of the Hawaiian Islands millions of years into the future is seen to the northwest in the spires of French Frigate Shoals and the remnants of other once mighty islands, ancestors of today's Hawaii, but now sunken beneath the sea through the forces of waves, rivers, and the slow subsidence of the seafloor," explained USGS Director Marcia McNutt.
"These data have allowed State and County agencies in Hawai'i to account for shoreline change as early as possible in the planning and development process so that coastal communities and public infrastructure can be sited safely away from erosion hazards areas," said William J. Aila Jr., Chairperson, Department of Land and Natural Resources, State of Hawai'i. "This will vastly improve upon public safety and will ensure that Hawaii's beautiful beaches will be protected from inappropriate shoreline development."
Of the three islands, Maui beaches experienced the highest rates and greatest extent of beach erosion with 85% of beaches eroding. Erosion is the dominant trend of coastal change on all three islands with 71% of beaches eroding on Kaua'i and 60% of beaches eroding on O'ahu.
The researchers found that, although Hawai'i beaches are dominated by erosion as a whole, coastal change is highly variable along the shore – with 'cells' of erosion and accretion typically separated by 100s of feet on continuous beaches or by rocky headlands that divide the coast into many small embayments. Most Hawaii beaches are composed of a mix of sediment derived from adjacent reefs and from the volcanic rock of the islands. Sediment availability and transport are important factors in shoreline change, and human interference in natural processes appears to have impacted the measured rates of change. For example, more than 13 miles of beaches in the study were completely lost to erosion – nearly all previously in front of seawalls.
"Over a century of building along the Hawaiian shoreline, without this sort of detailed knowledge about shoreline change, has led to some development that is located too close to the ocean," said Dr. Charles Fletcher, UH Geology and Geophysics Professor and lead author. "A better understanding of historical shoreline change and human responses to erosion may improve our ability to avoid erosion hazards in the future."
The researchers used historical data sources such as maps and aerial photographs to measure shoreline change at more than 12,000 locations. Shoreline changes are measured in specialized Geographic Information System (GIS) software.
This analysis of past and present trends of shoreline movement is designed to allow for future repeatable analyses of shoreline movement, coastal erosion, and land loss. "The results of this research provide critical coastal change information that can be used to inform a wide variety of coastal management decisions," said Dr. Rob Thieler, sponsor of the study with the USGS.
The research was also supported by grants from a number of federal, state, and county agencies as well as non-profit organizations. The report, titled "National Assessment of Shoreline Change: Historical Shoreline Change in the Hawaiian Islands," is the sixth report produced as part of theUSGS's National Assessment of Shoreline Change project, which already includes the U.S. Gulf of Mexico and Atlantic coasts, as well as California. An accompanying report that provides the GIS data used to conduct the Hawaii coastal change analysis is being released simultaneously.Research Contact:
Marcie Grabowski | EurekAlert!
Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel
Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)
A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.
In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...
A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.
By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
23.02.2018 | Physics and Astronomy
23.02.2018 | Health and Medicine
23.02.2018 | Physics and Astronomy