Technical Studies


Effect of Migration Behavior of Sand/Rock Bed on Channel Stability(2/3)

he purpose of this study is to examine the influence of migration process of main channel along the sand/rock bed river on channel stability. The sediment transport mechanism along the channel with compound cross section is analyzed by means of characteristics analysis and field investigation. The outcome from the theoretical analysis and application study is expected to be annotated as guidelines for hydraulic engineers in their designing and planning.

The annual report of this research project presents a sand bank failure experiment with considerations of geometric shape, stage drawdown and lateral bank erosion. The WRA model (2007) is adopted to simulate proposed experimental data and to analyze time and angle of bank failure. On the other hand, as known so far, there is still no suitable model for the sand/rock bed channel migration behavior. This study continues to extend the RESED2D model, which is a 2D depth-averaged mobile-bed model, to couple with capabilities of simulation of bed-evolution and river bank erosion/sliding. The two mechanisms including sand/rock bed evolution and river bank (sand material) sliding are jointly computed and applied to specific reach with sand-material bed in Jhuoshuei River.

Currently the rock erosion and bank failure mechanism are tentatively embedded in RESED2D model and applied to certain reach of Jhuoshuei River. Comparison of simulation results and the data observed from the field before and after typhoons event is also presented. The outcome of this study on Jhuoshuei River will be valuable for future improvement projects.