Determination of Nearshore Wave Climate using a Transformation Matrix from Offshore Wave Data

Abstract

Ly, N.T.H. and Hoan N.T., 2018. Determination of nearshore wave climate using a transformation matrix from offshore wave data. In: Almar, R.; Almeida, L.P.; Viet, N.T., and Sall, M. (eds.), Tropical Coastal and Estuarine Dynamics. Journal of Coastal Research, Special Issue No. 81, pp. 14–21. Coconut Creek (Florida), ISSN 0749-0208.Nearshore wave climate is important for the assessment of coastal process and morphological changes. For port engineers, nearshore wave climate is crucial for the determination of operational conditions and downtime analysis. The nearshore wave climate is often derived by translation of the 10 to 30-year offshore time series to nearshore. Direct transformation of such large amount of observations is not feasible, since it requires an extremely long computational time. This paper describes an advanced technique to quickly derive nearshore wave conditions from offshore wave data. First, determination of matrix of boundary conditions in which matrix nodes are chosen to cover wave conditions at offshore boundary. Then, simulations of wave for each condition as described in the selected matrix of offshore conditions. The results are used to determine the matrix of wave conditions for any given nearshore location. This matrix consists of factors that specify the relation between the offshore (model forcing) and nearshore (model results) wave parameters. With this matrix, offshore wave observations can be translated to any nearshore location. With this technique, a 30-year long time series of offshore wave measurement can be rapidly (less than 2 days) translated to nearshore wave conditions. This paper discusses in detail the working principles of the technique, as well important aspects such as the optimization of boundary conditions matrix.