Slope- watershed coupling simulation under different vegetation coverage
based on GAST model
Abstract
A non-equilibrium sediment transport soil erosion model based on finite
volume method (FVM) coupled with two-dimensional hydrodynamic process is
proposed, application of the GPU techniques in the numerical model,
making it possible to simulate the sediment transport and bed evolution
in a high resolution but efficient way. The first-order Gudonov format
FVM is used to discreting the control equation. The variables on both
sides of the unit interface are obtained by limiting slope
interpolation. An efficient and robust non-negative depth reconstruction
algorithm is used to solve the dry-wet boundary problem. This algorithm
makes the model have second-order accuracy in space, and also
effectively suppresses the numerical oscillation. Harten, Lax van Leer
Contact (HLLC) approximate Riemann solver is used to calculate mass and
momentum flux, and the friction source term is calculated by the
proposed split point implicit method. These values are evaluated by a
novel 2D edge-based MUSCL scheme. The code is programmed using C++ and
CUDA, which can be run on GPU to greatly accelerate the calculation
speed. In this paper, two numerical experiments show that the model
performs well in accuracy and robustness of the algorithm in the process
of slope erosion and watershed erosion. The constructed model can
simulate the soil erosion of slope and watershed gully under different
vegetation coverage, and characterize the erosion process of interaction
between slope and gully.