Aborting due to too many negative depth error

EFDC+
1

Hello,

I am running a model for a large lake, there is recirculation, aeration, outflow for irrigation, and inflow of urban runoff. When I run the model I get the error “ABORTING RUN DUE TO TOO MANY NEGATIVE DEPTHS” as seen bellow.

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After reading the other topics relating to negative depth, I changed the time step and ensured the water depth was accurate however I still get this issue. what is the cause of this issue and how do you fix it?

Thank you for your help,

2

Hello jpenderghast
Usually, these issues will be related to the time step, but there are some cases also due to incorrect settings or model inputs time series, if you changed the time step and still get this issue I think you can send me the model I will check it more carefully below is my email address
bmhoa@dsi.llc

Sincerely,

3

I am also getting same problem, any solution?

4

Hi ha626
Here are some suggestions to fix negative depth related errors:

  1. Reduce the Safety Factor:
    EFDC+ uses a safety factor to automatically control the time step. Try lowering this factor.

  2. Decrease the Initial Time Step:
    Especially at the beginning of the simulation, when the flow is still stabilizing, it’s better to use a smaller time step

  3. Check the Entire Model Domain:
    Use the 2D Plan View to observe the Water Surface Elevation. If you see a “checkerboard” pattern (alternating high and low water levels between adjacent cells), it’s a clear sign the model is numerically unstable.

    Although EFDC+ may continue running in this unstable state, it often leads to errors like negative depth later.

  4. Review the Grid and Input Data:

    • Check for unrealistic bathymetry, such as sharp or steep slopes.
    • Verify that boundary conditions (e.g., inflows) are not too large or rapidly changing.
    • Make sure the initial conditions are physically reasonable.

If after following the above suggestions you still get errors, please give me some images of your model, the last time it was displayed on 2DH, 2DV… we will look into them more closely
Sincerely,
BMHoa