Location identification of river bathymetric error based on the forward and reverse flow routing

River bathymetric data is fundamental to water flow simulation. In practice, due to measurement uncertainty and riverbed erosion and deposition, river bathymetric errors are inevitable. Therefore, identifying major cross sections with large bathymetric errors is of great significance. In this study, forward and reverse flow routing models were developed and then applied to obtain two different water stages for a specific cross section, which were respectively propagated from the upstream and downstream boundaries. The spatial variation of differences between the two calculated water stages was compared to quantify the influence of bathymetric errors, and then used as an indicator for the location identification of the bathymetric errors. After being tested and verified in a hypothetical river case, the identification method was then applied to the Xunjiang River case. The results show that the proposed method can effectively identify the cross sections with large bathymetric errors, and the identification performance is related to the flow magnitude. The research is valuable and practical to the improvement of river bathymetric data and the accuracy of water flow simulation.