Three dimensional numerical simulations of hydrodynamics and morphodynamics on rapidly varied channel

摘要

Erosion and sedimentation are severe problems in Taiwan’s river. The riverbed changes rapidlyrndue to the huge discharges that often have resulted a large amount of property damage and threats to the safety ofrnhydraulic structures. The 1-D or 2-D depth-averaged hydraulic model has the limitation for the understanding ofrndownward flow toward the bed. To investigate the hydrodynamics and local scouring on rapidly varied channel,rnthe study of 3-D numerical model is needed.This study presents 3-D numerical simulations of hydrodynamics andrnmorphodynamics on rapidly varied channel by implementing a novel erosion and sediment transport approachrnin a finite element based free-surface turbulent flow model. To simulate the bedrock river, a stream power typernof bedrock erosion rate formula is integrated in the 3-D model. An uplifted reach of Taan River, Taiwan, causedrnby the Chi-Chi earthquake occurred in 1999 is chosen as the study site to validate the model. The simulatedrnand measured results show that the proposed model has the capability of simulating morphological changes onrnrapidly varied channel.