Wave Attenuation and Friction Coefficient on the Coral-Reef Flat
摘要
Several sets of S4 direction-wave-current-tide meters have been deployed on the coral-reef flat of Yongshu Reef in the sea area of Nansha Islands. Based on the observational sea wave data, the attenuation characteristics of the waves propagating on the coral reef flat, the bottom friction coefficients and the transfer of wave energy are discussed in the paper. The results show that, in the relative depths of 0. 0613 ～ 0. 0867, the wave height attenuation per unit distance of wave propagation is 22.09 % ～ 46.56 %, with an average of 31.35 %; the wave energy attenuation coefficient, 33.74%～ 53.22%, with an average of 43.61%. The average of the bottom friction coefficients on the coral-reef flat is 0. 1346,which is about 10 times that on the sand or silt bottom. In the course of propagation on the reef flat, the waves sustain more loss in high frequency than in low frequency and the spectral energy transfers to the low frequency. These resuhs may be used for reference in island and reef engineering.