Hydraulic regime and morphology of a river section is in equilibrium if there is no human impact. However, under the human action impacts, the hydraulic regime and morphology of a river section have changed. The sediment imbalance in the river is usually caused by two factors, including the decline of sediment discharge from upstream when reservoirs were built and the sand mining. In particular, the sand mining process has a significant influence on the internal morphological changes as well as the river morphology at downstream section. In this article, a method of simulating the sand mining process on a mathematical model is presented and some results of morphological river prediction for the Thai Binh river are also shown in case of existing sand mining activities at the river upstream parts.