Abstract. Precise predictions of storm surges during typhoon events have the necessity for disaster prevention in coastal seas. This paper explores an artificial neural network (ANN) model, including the back propagation neural network (BPNN) and adaptive neuro-fuzzy inference system (ANFIS) algorithms used to correct poor calculations with a two-dimensional hydrodynamic model in predicting storm surge height during typhoon events. The two-dimensional model has a fine horizontal resolution and considers the interaction between storm surges and astronomical tides, which can be applied for describing the complicated physical properties of storm surges along the east coast of Taiwan. The model is driven by the tidal elevation at the open boundaries using a global ocean tidal model and is forced by the meteorological conditions using a cyclone model. The simulated results of the hydrodynamic model indicate that this model fails to predict storm surge height during the model calibration and verification phases as typhoons approached the east coast of Taiwan. The BPNN model can reproduce the astronomical tide level but fails to modify the prediction of the storm surge tide level. The ANFIS model satisfactorily predicts both the astronomical tide level and the storm surge height during the training and verification phases and exhibits the lowest values of mean absolute error and root-mean-square error compared to the simulated results at the different stations using the hydrodynamic model and the BPNN model. Comparison results showed that the ANFIS techniques could be successfully applied in predicting water levels along the east coastal of Taiwan during typhoon events.

A three-dimensional hydrodynamic model was implemented and applied to the Danshuei River estuarine system and its adjacent coastal sea in northern Taiwan. The model was calibrated and verified with the available hydrological data measured in 2000. A detailed model calibration and verification was performed using field data which consisted of the measured amplitudes and phases of five tidal constituents, water surface elevations, tidal current and salinity distributions. The overall performance of the model was in qualitative agreement with the field data. The validated model was then used to investigate the changes in salt water intrusion and residual circulation as a result of channel regulation in the Keelung River. The residual circulations before channel regulation differed slightly from those after channel regulation and the result for the limits of salt intrusion before channel regulation were only slightly different from those after channel regulation. At the Kuan-Du wetland, the saline difference was only 0$3 parts per thousand. These results suggest that the channel regulations for flood control in the Keelung River made no substantial contribution to the expansion of the mangrove areas and disappearance of freshwater marshes in the the Kuan-Du wetlands.