Modeling of Flow Resistance in Mangrove Swamp at Mouth of Tidal Keelung River, Taiwan

Abstract

The effects of mangrove trees on the flow field in a tidal estuary during high freshwater discharge events are investigated using a depth-averaged two-dimensional hydrodynamic model. The model is refined to include the effects of mangrove trees on flow resistance. The resistance is described by a set of two empirical equations depending on water depth and vegetative parameters. The vegetative parameters are investigated and tested using on-site samples of Kandelia plants. The model is calibrated and verified with experimental data measured in a physical model. The agreement between the measured and computed water surface elevation is good. The model is then applied to the entire tidal Tanshui River system, which includes mangrove swamps near the mouth of the Keelung River. The flow patterns and resistance distributions are investigated for several scenarios of high flow events. The results show that the refined model provides an ideal management tool for the mangrove swamps.