TUFLOW Message 2118
CHECK 2118 - Lowered SX ZC Zpt by <change in 2C cell elevation> to 1D node bed level.
WARNING 2118 - Lowered SX ZC Zpt by <change in 2C cell elevation> to 1D node bed level.
Lowered SX ZC Zpt to 1D node bed level.
A "Z" flag has been used to adjust the ZC elevation at each cell at/along the 2D SX object to below the 1D node bed elevation where ZC is higher. The ZC elevation is set to the Cell Wet/Dry Depth below the 1D node bed. It is not recommended to use the Z flag without first checking that the reason for the discrepancy in elevations between 1D and 2D domains is appropriate.
The "Z" flag lowers only the cell centre (ZC) and if used inappropriately can result in stability issues if there is a discrepancy between 1D node and surrounding 2D elevations.
The message switches from a CHECK to a WARNING at 0.3m (or 1 ft if using English Units) to draw further attention to large changes that may indicate potential erroneous inconsistency between the pit/channel level and the ZC ground level.
Check elevation at 1D node and 2D cells, if a large discrepancy exists, review levels. For example a 1D pit with an elevation (from survey) maybe significantly below the elevation in the DEM. Using a SX connection with a Z flag will lower the cell centre to below the 1D level, but will not lower a flow-path into pit and may cause stability issues. To lower flow path into the pit, Z shape polygon can be used.