The simulated water level and the actual measurements are compared to calculate the residuals. The corresponding statistical results calculated as Equations (20) and (21) (root mean square error (RMSE) and correlation coefficient R) are summarized in Table 1. It is found that the model errors unavoidably exist at all measurement locations. In addition to general limitations of the numerical model, such residuals may also be attributed to the complex hydrodynamic behavior in this area resulting from water exchange between the Indian and Pacific oceans. Therefore, it is important to apply a data assimilation method to correct SRM and improve its accuracy:where, is the observed water level; x the water level from the numerical model; and n the number of records.