Performing a river section conveyance check

Step-by-step guide

The conveyance calculated for river sections is important for the accuracy and stability of a model. If there are abrupt changes in roughness or slope, then a panel marker may not need to be set at each change. This is a manual process if they are not included in the original import. The panel markers assist in the calculation of the conveyance curve that is used during simulations.

To complete this exercise, copy the network out of the transportable database .icmt file for this tutorial or carry on from the previous exercise.

1. From the Database, double-click the 1D River Model to open it on the GeoPlan.

2. From the Modelling Grid Windows toolbar, select New lines window.

3. In the Cross section line window, in the table margin of cross section ID 16, right-click and choose Select and find in geoplan.

4. From the More GeoPlan Tools toolbar, click Conveyance Graph Pick.
5. On the GeoPlan, click the selected cross section to open the graph.

It should be a smooth curve from the bottom-left to the top right. The conveyance of this curve currently drops back down as the elevation increases, which can cause simulation instability. To correct this, add panel markers to aid the calculations:

6. Close the graph window.
7. Select Tools > Options.
8. In the Options window, switch to the General tab.
9. Enable Allow editing of river reach data.

This allows the river section data to be altered directly. Otherwise, the cross section line data would need to be updated first, and then the river reach section data would need to be built again to update it.

10. Click OK.
11. In the GeoPlan Tools toolbar, click the Select tool.
12. On the GeoPlan, double-click the 16DS river reach to open the Properties window.
13. In the River sections row, click the More (…) button to open the sections data.

14. In the River sections data window, under Sections, select 16.
15. Under Survey Points, for rows 7 and 34, enable New panel.

This adds panel markers at the top of the banks where there is an abrupt change in slope, especially on the left hand side. The panel markers are indicated in the graph by vertical blue lines.

16. Click OK.
17. Click Conveyance Graph Pick.

18. Click the 16DS cross section to open the graph.

The graph line is now smoother and monotonic.

19. Close the graph.
20. Click Commit changes to database.
21. Add a comment of “River section data imported and checked”.
22. Click OK.
23. In the validation popup, select No. This model contains errors, as it is not fully connected.