. Atoll research bulletin. Coral reefs and islands; Marine biology; Marine sciences. 112 Eastern Islands Aidhoo (Figure 3). Aidhoo, the easternmost of the surveyed islands comprises a sequence of gravel ridges on its eastern margin, whereas the western end of the vegetated island is composed of sand. A sand spit extends lagoonward, towards the northwest for over 150 m across the reef platform. Comparison of pre- and post- tsunami GPS surveys indicates that the vegetated island area was reduced by 9% with most of this reduction occurring along the southern and northern shorelines where erosiona
. Atoll research bulletin. Coral reefs and islands; Marine biology; Marine sciences. 112 Eastern Islands Aidhoo (Figure 3). Aidhoo, the easternmost of the surveyed islands comprises a sequence of gravel ridges on its eastern margin, whereas the western end of the vegetated island is composed of sand. A sand spit extends lagoonward, towards the northwest for over 150 m across the reef platform. Comparison of pre- and post- tsunami GPS surveys indicates that the vegetated island area was reduced by 9% with most of this reduction occurring along the southern and northern shorelines where erosional scarping was notable (Fig. 3). Little change was detected in the toe of beach GPS surveys, and in the profiles across the eastern gravel ridge sequence (Fig. 3 b). Note however, that the beach toe retreated a short distance along both the northern and southern flanks of the island. In contrast, the trailing sand spit extended lagoonward both to the north and west toward the edge of the reef platform and beyond the footprint of the beach of earlier surveys. This expansion represents an increase in beach area of about 37% which extends across approximately 5,000 m2 of reef surface. Figure 3 also shows that the island surface experienced wave inundation from the tsunami. Overwash sediments consisting of discontinuous veneers of sand together with deposits of coarser coral gravel covered approximately 17% of the vegetated island surface extending from the eastern end of the island along most of the northern _| Vegetated island [ H Overwash deposition I Eroded island I Survey benchmark Toe of beach — Jan 02 & Feb 03 _ Toe of beach June 02 ' Toe of beach & J Tsunami-induced scarping survey profile Feb 05 ff Tsunami-induced gullying Figure 3. Pre- and post-tsunami plan and profile changes on Aidhoo Island. Location of island shown in Figure Please note that these images are extracted from scanned page images that may have been digitally enhanced for readabi
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