How to calculate mass balance error


I found this web page mentioned ‘’ if they have rapidly changing bathymetry at the open boundary then it is possible to get mass balance errors.’’

How do I know if the model gets mass balance errors? And how to calculate?

Thank you.

You can tell if you are likely to be getting mass balance errors by a visual inspection of the cells in the region of the open boundary. Unrealistic concentrations near the BC are an indication of mass balance problems. Open BCs should not be close to the area of interest so flattening the cells in that region to ensure mass balance should not impact the results.