Modelling effects of realignment of Keelung River, Taiwan

Abstract

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.