Potential 1D-2D balance error

[Behzad Jamali]

I see a potential water balance error when modelling 1D-2D. A flow limiter is implemented for situations where water flows from the 2D domain to SWMM:

## flow limiter ##

# flow leaving the 2D domain can't drain the corresponding cell

if new_linkage_flow < 0:

    maxflow = (h * cell_surf) / dt1d

    new_linkage_flow = max(new_linkage_flow, - maxflow)

However, there is no such limiter when the flow is from SWMM to 2D domain. If the node head level in the 2D model is much larger than the water level in the 2D domain, the calculated `new_linkage_flow` can potentially be much larger than what exists in the 1D model.

In my test simulations, I get more water on the surface when the flow source is surcharge from SWMM (sometimes the volume of water on the 2D domain is 100 times more than the total runoff).  

[Laurent C.]

Hi Behzad,

Thanks for you e-mail. Indeed Itzï does not implement a flow limiter on the flow leaving the drainage network. I did some tests with outflow limiter. However the flow was much lower than other models according to the EA report.

For more details on that matter you can have a look at the doctoral thesis, especially in Section 3.2.4:

https://thesiscommons.org/38w4t/

Ideally the model would be calibrated against reality, but this information is difficult to obtain.

Best regards,

Laurent

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