Skip to content

FAQ/ Setting a culvert wider than the mesh size

How do I set an embankment that is wider than the mesh size of the flood model?

For example, if the mesh size is 5 m, I want to set a culvert with a width of 10 m.

If you set an embankment in DioVISTA with a width that exceeds the mesh size of the flood model,

The culvert width is greater than the calculated mesh size.

and an error message is displayed, and the simulation cannot be performed.

However, we know that this behavior is normal and that the Technical Reference Boundary Conditions - Structures-Culverts states that an error is displayed if the width or height exceeds the mesh size.


If you set embankments or culverts that are wider than the mesh size, consider representing them as terrain. I think it is convenient to use the terrain editing function for this. For more information, please refer to the Technical Reference "Map Data - Topographic Editing Features".

The "Manual for Drawing Flood Expected Areas (4th Edition)" (Reference 6) contains the following requests.

Manual for Mapping Flood Areas (4th Edition) p. 19

3.1. Basic concept of flood analysis
(8) Continuous embankment, etc.
In order to more appropriately express the inundation phenomenon, continuous embankments whose embankment width is small with respect to the mesh width and cannot be sufficiently expressed by the ground height are modeled as impermeable boundaries when the inundation level does not exceed the embankment height, and overflow occurs when they are exceeded. Conversely, continuous embankments that are sufficiently wide with respect to the mesh width can be given as topographic conditions and continuously inundation calculations can be performed (see Figure 3.2-6).

Last update: 2023-03-17