AUCKLAND,12 FEBRUARY 2018 (STUFF NZ)–The tiny Pacific nation of Tuvalu – once thought to be under threat from rising sea levels – has grown the size of California’s Disneyland over the past 40 years.
It’s mostly thanks to waves dumping extra sediment, sand and gravel on shore lines, according to research by Auckland University scientists.
The study, published in the Nature Communications journal on Friday, was the first in-depth look at how much each of Tuvalu’s 101 islands have changed over the decades.
The islands, which are spread over nine atolls, were found to have experienced a total net increase in land area of 2.9 per cent, or 73.5 hectares, since 1970.
That is about the size of 73 rugby fields.
Eleven of Tuvalu’s islands have a permanent human population, but only two have a population of more than 600.
“The key take-home message for the people of Tuvalu is how variable the changes in their islands are,” study co-author Murray Ford said.
The research highlighted the need for authorities to keep a close eye on which islands were growing and which were shrinking, as the uneven fluctuation of island size would influence internal migration patterns in the future.
Overall, 73 islands were found to be larger now than 40 years ago – even taking into account rising sea levels.
“The study findings may seem counter-intuitive given that sea level has been rising in the region over the past half-century,” co-author Paul Kench said.
“But the dominant mode of change over that time on Tuvalu has been expansion, not erosion.”
The study identified waves to be the main change driver for “island morphological adjustment”.
Waves, and in particular, storm waves influence the shape and size of islands.
For example, Cyclone Bebe in 1972 delivered significant volumes of coarse sediment to the Funafuti reef flat, which expanded the footprint of the islands on their eastern rim over the next four decades.
“We tend to think of Pacific atolls as static landforms that will simply be inundated as sea levels rise but there is growing evidence these islands are geologically dynamic and are constantly changing,” Professor Kench said…..PACNEWS [/restrict]