This study contains two topics which are important for the use of a one-dimensional computer model, calculating morphological changes in time. Firstly, for a good prediction of the morphological changes by the model a good reproduction of the water movement and the sediment movement is necessary. One of the conditions for a good reproduction of the process is a good schematisation of the river cross-section in the model. In the river cross-section, a good reproduction of all the parameters playing a role in the morphological process is required. Several schematisation-methods are treated, considering a fluctuation in the discharge and irregularly shaped cross-sections. The second topic of this study considers the interpretation of the calculated morphological change to the real cross-section. The calculated morphological change is distributed over the width of the cross-section in several ways, each distribution with his own physical background. The results show an influence of the distribution-option on some practical parameters. For both topics data are used of the Da River in Vietnam and of the River Waal in the Netherlands.