Inversing open boundary conditions of tidal bore estuary using adjoint data assimilation method

The adjoint equations of the nonlinear shallow water conservative equations are set up,and the formulas for adjusting the open boundary conditions of unstructured triangular meshes are presented,based on the idea of the Godunov scheme and the Roe's scheme.The adjoint model used to invert the open boundary is founded based on the unstructured triangular meshes and finite volume method.The adjoint model is used to inverse the open boundary conditions of the generalized tidal bore estuary and the Qiantangjiang tidal bore estuary through some iterations.The average errors of amplitude along the open boundary are 0.000 6 m and 0.053 3 m respectively.The results indicate that the adjoint model is viable and adaptable to the discontinuous solutions.