| Popis: |
The analysis carried out in this work is aiming at evaluating the capability of different mathematical models to reproduce both long- and short-term changes in river beds. To this purpose, the paper illustrates and compares three different one-dimensional models of river dynamics, all bassed on simplifying hypotheses, such as: non prismatic channels of rectangular cross section shape, with unerodible banks and mobile bed; sediments uniform in size and homogeneous in density; hydrostatic pressure distribution. Comparison of the three models maker reference to the expressions and the signs of the slopes of the characteristic directions that can be derivered from each model. Then, these slopes can be used to compare the models with respect to how and where boundary conditions have to be assigned. Finally, a discussion and comparison are provided, in order to evaluatr the possibility of decoupling the momentum and continuity equations for water from the continuity and transport equations for sediment. |
