Dynamic Modeling of Meandering Alluvial Channels
Abstract
The migration of meandering alluvial channels is investigated theoretically, numerically, and experimentally. An equation for the rate of bank erosion is derived from a twodimensional continuity equation for sediment transport linked with the depthaveraged dynamic flow equations. A simple onedimensional theoretical analysis of meander migration leads to a relationship between the migration rate and the relative channel curvature and sediment properties. The simple model appropriately simulates the pattern and rate of meander expansion and migrations of the White River, Indiana and the East Nishnabotna River, Iowa. Application of the onedimensional model to sine generated alluvial channels indicates that meander migration reaches its maximum when the relative radius of curvature reaches about 4.8, or when the sinuosity of meander approaches 1.3. A twodimensional numerical model, DYNAMIC, which predicts both lateral and longitudinal migration of alluvial channels is then developed, based on a system of quasi steady depthaveraged flow dynamic equations, a sediment continuity equation, and a bank erosion equation. A linear analysis of the twodimensional model leads to a convolutional relation between the rate of meander migration and flow and sediment properties. In the twodimensional numerical analysis, a numerical algorithm called FLOWSOL is developed to solve the flow dynamic equations. The flow algorithm is then linked to the sediment continuity equation and bank erosion equation to simulate bed deformation and bank erosion. The developed twodimensional model is applied to calculate the velocity profiles in Rozovskii's experiments and the bed deformation and shear stress in Hooke's experiments. Good agreement is obtained between the calculated and measured velocities, shear stresses and bed profiles in all experiments. Small scaled meandering rivers are developed successfully on a floodplain with or without cohesive materials (about 3%) in a wide recirculating flume. The lateral migration of miniature rivers under relatively constant flow discharge is documented, analyzed, and compared with simulation results by the twodimensional numerical model.
 Publication:

Ph.D. Thesis
 Pub Date:
 January 1990
 Bibcode:
 1990PhDT.......213L
 Keywords:

 EROSION;
 Engineering: Civil; Physics: Fluid and Plasma; Hydrology