On A Quasi-Two-Dimensional Simulation of Scour and Deposition in Alluvial River Network

• Main Authors: Hsieh,Hui-Ming, 謝慧民
• Other Authors: Lee,Hong-Yuan
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/9dh868

博士 === 國立臺灣大學 === 土木工程研究所 === 84 === Most existing sediment routing models are one-dimensional models and hence cannot be used to simulate lateral channel bed deformations. Network or braided type channel geometry can be found in most alluvial rivers,and current sediment routing models are not applicable in these conditions. Basing on the state-of -the-art sediment transport theorem and numerical method , a quasi-two-dimensional model for scour and deposition simulation in an alluvial channel network was developed in this study. This model , named NETSTARS , has following capacities: (1). Both unsteady and steady flow routing schemes are available to calculate water stage and discharge in a network. It is also able to simulate sophisticated flow conditions such as hydraulic jump, drop and supercritical flow conditions. (2). Using the stream tube concept, this model is capable of simulating lateral variations of channel cross-sections in a channel network. (3). It is able to reflect different behaviors of nonuniform sediments during scouring and depositing process. (4). The model has an option to treat the suspended load and bed load separately and hence is able to simulate the deposition behaviors of the suspended sediment under a nonequilibrium process. An assessment of the model''s performance has been conducted through comparisons with analytical solutions and field data. Two river systems and three hydraulic laboratory data were used. It indicates that this model is numerically very stable and accurate. A dimensionless coefficient ,CO=(ALT * the largest size diameter * Δx * width of channel)/ (flow discharge * Δt), was found the range from 0.0001 to 0.001 in the above-mentioned simulations. Combining with the Courant condition ,it can be used to predict the ranges of the model''s parameters .