A finite-volume numerical model is presented for the calculation of three-dimensional turbulent flow in meandering channels with natural bed configuration. The governing equations are written in a general curvilinear coordinate system so that all singly connected geometrical configurations can be accommodated. For simplicity, the Cartesian velocity components are retained as dependent variables. The numerical procedure is very general so that it can deal with complex cross sections and separated flow. Turbulence closure is through the standard k-ϵ model. Computed results show good agreement with experimental data in meandering channels with rectangular and natural bed configurations. This work provides a hydrodynamic basis for the study of the mechanisms for the formation of river meanders. ¿ American Geophysical Union 1993