FAQ/ Location of the cross-section where lateral inflow is given¶
If a river is fed with lateral inflow, to which cross-section is its flow rate added? Since DioVISTA uses a staggered grid for the river channel model, the position of the flow rate and the position of the cross section seem to be different.
The lateral inflow is given to the section closest to the specified inflow.
For example, define a river channel section every 200 m from 0 m at the downstream end. The position of lateral inflow is a distance mark of 201 m. In this case, the nearest cross section is the section with a distance mark of 200 m. The lateral inflow is added to this cross-section (the lateral inflow is given on the right side of the continuous equation. ）
Also, as you pointed out, DioVISTA uses a staggered grid. In this staggered grid, the water level and depth are in the cross-section. Flow velocity and flow rate exist between cross-sections.
As a result, the water level rises in the cross section closest to the point of lateral inflow. Then, downstream of that cross-section, the flow rate increases.
However, in the screen display of DioVISTA, the water level and depth present in the cross section are displayed at that position. The flow velocity and flow rate that exist between the cross-sections are also displayed at the cross-sectional position (only half of the cells are shifted downstream).