Tidally induced cross - shore sand - mud transport and long-term bed-profile evolution

A one-dimensional numerical model based on the shallow-water equations, suspended- sediment transport formulae and bed-material conservation equation was developed in order to study the morphological behaviour of idealised hump bed under cross-shore tidal current. A series of tests were carried out for some benchmark problems, such as wave propagation and hump morphodynamics, to validate the numerical scheme. The system of hydrodynamic equations was solved using the finite-volume numerical scheme associated with approximate Roe s Riemann solver, a data-reconstruction and slope limiter. Hump beds consisting of sand/mud mixtures were examined. It was found that the predicted morphological behaviours of the hump beds under the cross-shore tidal current for a five year period show quite similar trends and the height of hump- profiles is reduced at the top and increased at both sides. Moreover, sand content of 40 percent produces the highest peak of hump-bed profile. This study shows that the amount of decreasing and increasing of bed-profile depends on the critical shear-stress and quantity of sand and mud in the sediments fraction.