Question
How can I create a dfsu file with the exact same bathymetry values as in a dfs2 file?
Answer
You can convert a domain bathymetry from a dfs2 file to a dfsu file by running a simple MIKE 21 FM HD model. The process is as follows:
1. Setup a MIKE 21 FM HD model using the dfs2 file as domain bathymetry
2. Specify 0 time steps
3. Set initial water level such that there is no water in the model, e.g. to -1000
4. Set all open boundaries to land
5. Make sure no infiltration, precipitation, evaporation, or sources are included.
6. Define an area output, using 'Discrete values' and 'Whole domain' and select the output item 'Surface elevation' as the only item in the output dfsu file (see Fig. 1 below)
7. Run the model
You have now created a dfsu file where the bathymetry values at the center of the elements correspond to the values from the grid cells in the dfs2 file. This file can be modified or used directly in MIKE+.
Fig. 1 - Specifying output in MIKE 21 HD model
An example of the result of the process is shown in Fig. 2.
Fig. 2 - Original bathymetry in dfs2 file (upper), generated bathymetry in dfsu file (lower)
Optional: Change item type
If you want to apply the dfsu file in MIKE 21 HD FM as a Depth correction to a mesh with a flat bed at level zero, the item type is required to 'Bed level change'.
You can change the item type to match the requirement from a GUI. The process is as follows:
1. Open the dfsu file in Data Utility
2. Change the item type and item name to 'Bed level change' (see Fig. 3)
3. Save the file and close Data Utility
Fig. 3 - Changing item name and item unit
FURTHER INFORMATION & USEFUL LINKS
Manuals and User Guides
MIKE 21 Flow Model FM User Guide
MIKE+ 2D Overland User Guide
MZ Data Utility Online help