Hydrodynamic model calibration for a mesotidal lagoon: the case of Ria de Aveiro (Portugal)

Abstract

Ria de Aveiro is a shallow vertically homogeneous mesotidal lagoon, located in the Northwest of Portugal. It has a very intricate morphology and large tidal flats area s that cover and uncover al ong the tidal cycle. A two- dimensional vertically integrated hydrodynamic mode l was considered to be adequate to simulate its hydrodynamics and a model developed from the SIMSYS2D model was applied. The purpose of this study is to describe the implementation a nd calibration of this model which is able to predict tide-induced water level and depth integrated velocity for the entire lagoon. The numerical bathymetry used was developed from data concerning depth obtained from a general survey carried out in 1987/88 and actualised for several channels in the last years. The Monte Carlo method wa s used to generate the rectangular computational grid, which has 409 cells in the eastward direction and 966 cells in the northward direction (dimensions of 40 × 40 m). The model calibration was performed adjusting the bottom friction co efficient for the entire lagoon, through the comparison between measured and predicted time series of sea surface elevation (SSE) for a large number of stations distributed along the main channels of the lagoon. The re lative mean absolute error, the root-mean square and a skill assessment of the difference between those SSE values were determined to quantify the models performance. Harmonic analysis was also performed in or der to evaluate the model accuracy. According to the results the hydrodynamic model was successfully calibrated, reproducing accurately the barotropic flows in this complex lagoon.