MIKE 21 BW - Sign Convention

Reference Manual
116 MIKE 21 BW - © DHI
Figure 5.7 MIKE 21 BW Model Setup Planner efficient model setup and execution
Example
A minimum wave period of T
min
= 6 s and a minimum water depth h
min
= 4 m
gives a minimum wave length of L
min
= 35 m.
Grid Spacing: The grid spacing should then be at least 35/7 = 5 m, in order
to ensure 7 grid points per wave length.
Sign convention
Bed levels (water points) are specified as negative values when they are
below the bathymetry datum, and positive values when they are above it.
Note that simulations are carried out using the still water level (SWL) as refer-
ence. SWL = bathymetry value + shift of reference level, see Figure 5.8.
Example
As an example, consider a bathymetry created using LAT as datum. You wish
to run a simulation for mean sea level (MSL). The MSL is 1.0m above LAT, so
you specify +1.0m as shift of reference level. At a point where the bathymetry
bed level is -7.0m, the total water depth becomes
-(-7.0m) +1.9m = 8.0m.