To study applicability of the MIKE 21C, a river reach of the Brahmaputra River near Palashbari, which is suffering due to devastating bank erosion, has been selected. Preliminary observation, imaginary based study, model simulation has been carried out. The model study has also been performed using various bank protection measures. The computed hydrodynamic results resemble the actual field condition. The results showing bank erosion, morphological changes, are also quite logical. However, several input data are required for the simulation of the model. Though field data have been collected for some of the important parameters, default value or approximate value chosen on the basis of general experience has been used for some less important parameters. Extensive data collection is necessary for obtaining convincing results. Sensitivity of two parameters, eddy viscosity and Chezy coefficient, has been done. Sensitivity analysis of the model has shown that while eddy viscosity is quite sensitive, Chezy's coefficient is less sensitive particularly during flood period.