Abstract

This paper presents a study of two-dimensional modelling for alluvial rivers in mountain areas, following a sustained research program. On the basis of sediment exchange mechanism, improvements are made in relation to the calculation method for river-bed deformation. The modes of non-homogeneous suspended load transport and non-homogeneous bed load transport are substantiated. Following that, a depth-averaged two-dimensional mathematical model is established under the orthogonal curvilinear body-fitted coordinate system with staggered grid. The governing equations of flow and sediment are discretized with the finite volume method. The relaxation technique and line-by-line method are used in solution of the discrete equations. The computed water level, velocity and riverbed deformation from the mathematical model are verified by field data in the Bayoutan Reach of the Beipanjiang River. It is shown that the flow field and the process of riverbed erosion and deposition in mountain river can be simulated reasonably well. The proposed mathematical model is adopted in the West Development Program “Study on the Regulation Schemes in Bayoutan Reach of Beipanjiang River,” and put into practical problem solving.

Keywords: mountain river; river-bed deformation; body-fitted coordinate; finite volume method; mathematical river modelling