Google Earth画像はここ10年程度の期間における汀線変動を知る際にはきわめて有効であり，これまでも多くの海浜変形に関する研究において使用されている．ただし，撮影時刻が示されていないことから，汀線判読にあたって潮位補正を行うことが出来ないという大きな欠点を伴っていた．そこで，晴天時に撮影された画像には建物など背の高い物体の影が写っていることが多いことから，この情報を活用して撮影時刻を推定する手法を提案した．まず，長期にわたり撮影画像が蓄積されている仙台海岸を対象に同手法を適用し，既知の撮影時刻との比較により，推定時刻の誤差が最大でも7分ほどであることを明らかにした．その後にGoogle Earth画像への応用を試み，この補正の有無が中期的な汀線の後退・前進の判断に及ぼす影響を検討した．
Golden Beach in south Taiwan is widely known and has been attracting many beachgoers. In recent years, this beach has been eroded and measures to restore the sandy beach are required. The cause of the beach erosion was investigated on the basis of bathymetric survey data. In the study area, northward longshore sand transport, which was induced by the wave-sheltering effect of Anping Harbor, prevails, and the rate of transport was estimated to be 1.25×105 m3/yr with the conditions of the depth of closure (hc) of -6 m, the berm height (hR) of 2.2 m, and the characteristic height of beach changes (h) of 9.2 m.
Numerous efforts have been made for the improvement of nonlinear energy transfer computation. Until now, the DIA method is generally used for evaluating nonlinear energy transfer Snl in the practical wave model because of its low computational cost. Tamura et al. (2008), suggested SRIAM developed by Komatsu (1996) to be incorporated into the operational wave model. The performances of the wave model were significantly improved by using SRIAM. However, the computational cost is still 20 times larger than the existing operational wave model using DIA. Therefore, we modified SRIAM by reducing the number of the resonant configurations. It was found that 9 numbers of configurations produce the nonlinear energy transfer approximately well as compared to the original SRIAM which has 20 numbers of configurations. This method is then called as the Reduced SRIAM (R-SRIAM). The configurations of R-SRIAM show that the quasi-singular quadruplets contribute the most to the nonlinear energy transfer than the regular quadruplets. Hence, we proposed the efficient number of resonance configurations by selecting only from the quasi-singular quadruplets to be included in the calculation, which is called as the Alternative Multiple DIA (AM-DIA) method. The reduced number of the resonant configurations makes the computational method of the nonlinear energy transfer more economically acceptable.