Jianchun Huang

Modelling of meander migration in an incised channel

Abstract An updated linear computer model for meandering rivers with incision has been developed. The model simulates the bed topography, flow field, and bank erosion rate in an incised meandering channel. In a scenario where the upstream sediment load decreases (e.g., after dam closure or soil conservation), alluvial river experiences cross section deepening and slope flattening. The channel migration rate might be affected in two ways: decreased channel slope and steeped bank height. The proposed numerical model combines the traditional one-dimensional (1D) sediment transport model in simulating the channel erosion and the linear model for channel meandering. A non-equilibrium sediment transport model is used to update the channel bed elevation and gradations. A linear meandering model was used to calculate the channel alignment and bank erosion/accretion, which in turn was used by the 1D sediment transport model. In the 1D sediment transport model, the channel bed elevation and gradations are represented in each channel cross section. In the meandering model, the bed elevation and gradations are stored in two dimensional (2D) cells to represent the channel and terrain properties (elevation and gradation). A new method is proposed to exchange information regarding bed elevations and bed material fractions between 1D river geometry and 2D channel and terrain. The ability of the model is demonstrated using the simulation of the laboratory channel migration of Friedkin in which channel incision occurs at the upstream end.

Development and Validation of GSTARS-1D, A General Sediment Transport Model for Alluvial River Simulation - One Dimensional

GSTARS-1D, Generalized Sediment Transport model for Alluvial River Simulation – One Dimensional, is the latest development in the GSTARS series. GSTARS-1D is a hydraulic and sediment transport numerical model developed to simulate flows in rivers and channels with or without movable boundaries. It is able to compute water surface profiles in single channels, simple channel networks, and complex channel networks. It has both steady and unsteady flow models, many sediment transport equations, floodplain simulation, and computation of width changes using a minimization theory. Lateral inflows can be simulated along with internal boundary conditions, such as time -stage tables, rating curves, weirs, bridges, and radial gates. Two examples are presented in this paper. The first example shows the capability of the network channel simulation with sediment transport. The second example illustrates the use of the unsteady flow and unsteady sediment transport features of GSTARS-1D in real engineering problems with hydraulic structures.