Author(s): Aly El-Dien Ahmed; Hiroshi Takebayashi; Masaharu Fujita
Linked Author(s): Hiroshi Takebayashi
Keywords: Fluvial erosion; Numerical model; Cohesive riverbanks; Boundary shear stress
Abstract: Based on the excess shear stress principle, a finite element model that simulates the temporal and spatial changes in the profile of cohesive riverbanks is developed. Two conjugate adaptive finite element meshes are used to represent both the river flow domain and the bank profile. The model predicts the distribution of boundary shear stress along the river cross section. The acting shear stress is continuously calculated, after each time step, according to the new updated bank profile. Accurate estimation of erosion progress in the riverbanks with layers of different material properties and shapes is obtained. The hydrodynamic variations in water surface level and river discharge at each time period are easily defined. A time marching procedure to calculate the minimum time step is described. Two test flumes were prepared to perform experiments to validate the numerical model. The first flume is to determine the erodibility coefficient and critical shear strength for cohesive bank material and the second flume is to measure the fluvial erosion that happens with time for different shear stresses. The fluvial hydraulic erosion model is validated by comparing its results with the experimental results. The comparison results are discussed.
Year: 2013