The use of remote sensing and linear wave theory to model local wave energy around Alphonse Atoll, Seychelles
This paper demonstrates a practical step-wise method for modelling wave energy at the landscape scaleusing GIS and remote sensing techniques at Alphonse Atoll, Seychelles. Inputs are a map of the benthicsurface (seabed) cover, a detailed bathymetric model derived from remotely sensed Compact AirborneSpectrographic Imager (CASI) data and information on regional wave heights. Incident energy at the reefcrest around the atoll perimeter is calculated as a function of its deepwater value with wave parameters(significant wave height and period) hindcast in the offshore zone using the WaveWatch III applicationdeveloped by the National Oceanographic and Atmospheric Administration. Energy modifications arecalculated at constant intervals as waves transform over the forereef platform along a series of reefprofile transects running into the atoll centre. Factors for shoaling, refraction and frictional attenuationare calculated at each interval for given changes in bathymetry and benthic coverage type and a nominalreduction in absolute energy is incorporated at the reef crest to account for wave breaking. Overallenergy estimates are derived for a period of 5 years and related to spatial patterning of reef flat surfacecover (sand and seagrass patches).
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