Views:

You have the following options to check the water balance from a coupled simulation:

Option 1
A mass balance summary is provided in the *.log file created during the simulation and contains a section called “Volume balance” related to the 2D component as illustrated in Fig. 1 for the FM version.

Fig. 1 - Volume balance related to 2D component for the MIKE 21 FM version

This summary is also provided in HTML file format in the same folder as the *.m21fm file.  This summary provides the initial and final volumes in the domain area, as well as volumes from sources / sinks, boundaries, precipitation / evaporation, and exchanged with 1D models.
Furthermore, you may check that the continuity balance is small compared to the volumes involved. 

Option 2
The “Water Balance” section obtained with the classic version of MIKE 21 is similar as illustrated in Fig. 2 below. This summary is also provided in HTML format in the folder containing the *.m21 file.
 

Fig. 2 - The “Water Balance” section obtained with the classic version of MIKE 21

Conclusion 
The Water Balance Summary shows a clear overview of the initial and final volumes in the domain area as well as volumes from sources / sinks, boundaries, precipitation / evaporation (here described as “Volume from process”) and exchanged with 1D models. It also includes two additional items: “Volume from transport” which is not used and always set to 0, and “Volume defect” which is the necessary volume correction applied when water level is below bed level.  The most important detail to check is whether the volume error is small in relation to the other involved volumes. 

FURTHER INFORMATION & USEFUL LINKS

Manuals and User Guides
MIKE+. 2D Overland. User Guide

Release Notes
MIKEPlus Release Notes 2022

Training options
MIKE+ CS - Getting started with urban drainage modelling 
MIKE+ 2D Overland Flow - Getting started with urban flood modelling

 

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