fluctuating river stage boundary condition at an embankment (2D vertical plane)

Hello  outthere!

currently we are investigating the pressure propagation dynamics at embankments/dikes in the case of rapid river stage fluctuations.
I am uncertain how to apply the right boundary conditions at the slope surface (2D vertical plane model) in contact to the river.
Initially one can apply heads below the water surface and seepage above. When the river water table rises, then initially set "seepage-nodes" must change to "head-nodes" as soon as they are submerged. With river stage case "head-nodes" must change to "seepage-nodes" as soon as the river stage falls below the elevation of the respective nodes.
I presume that there must be a way to consider these river stage fluctuations via some kind of constraints.

Any clues warmly appreciated!

Héctor

An IFM might be the best solution

Hello Pete,

thank you for your hint!

I have not applied IFMs yet, so  am not familiar to these kind of external subroutines.
Is there already one suitable for fluctuating river stage boundary conditions?

The only one I found was:
[i]VaryingBC[/i]: Sets and removes boundary conditions and/or constraints for specific time intervals and node groups.

However in the required case the shift in BC must depend on the elevation of the respective nodes relative to the BC accounting for the external river stage.

Any further ideas?

Héctor

The only other way (non IFM) would involve creating one constraint time series for each unique BC node elevation.  This would be rather impractical if you have many BC nodes.

However, it would be reasonably striaghtforward to export the nodes (with elevations), set up a spreadsheet to generate the constraint timeseries, making reference to the stage time series.  You can then batch import the timeseries and import a dataset with all the nodes and their corresponding time series IDs.

Minimum flow constraint time series would look something like this (assuming time series time is constant steps and node in question is flooded T = 100 - 200 days):

T            Q
0            0
100        -10000
200        0
300        0

If I understand you right you propose to assign a seepage boundary condition with a time variant constraint allowing so inflow during submersion for the specific nodes.
It sounds viable, at least in the case of simple  stage time series and a reasonable number of nodes. I will give a try!
Thank you very much for your support!