TUFLOW Message 2234

TUFLOW Message
ERROR 2234 - HQ boundary has zero slope and a blank boundary name.

Alternate Message
ERROR 2234 - HQ boundary has zero or negative slope - for TUFLOW HPC slope is required.

Message Type
ERROR

Description
TUFLOW Classic:
A HQ type boundary object is a head-flow or stage-discharge boundary. The stage discharge relationship can be specified by the user, by either:

• Specifying a "name" attribute for the HQ object in the 2d_bc layer, and linking this to a stage-discharge relationship in the boundary condition database (bc_dbase.csv).
• Alternatively a stage-discharge relationship can be automatically calculated by TUFLOW by giving a water surface elevation slope, this is specified in the "b" attribute of the 2d_bc layer (slope is in m/m or ft/ft).
  

Note: If both a boundary name and a water surface slope ("b" attribute) are specified in the 2d_bc object for the HQ boundary, the automatic (water surface slope) approach is adopted.
TUFLOW HPC - until 2020-01-AB:
Due to model splitting to parallelise the 2D domain across CPU or GPU cores, the HPC solver applies the HQ boundary slope to each individual cell along the boundary and doesn’t treat the HQ boundary as a single flow line. Therefore, the linking to a stage-discharge relationship in the boundary condition database is not supported.
TUFLOW HPC - from 2020-10-AA:
The linking to a stage-discharge relationship in the boundary condition database is supported.

Suggestions
TUFLOW Classic:
Specify a slope for automatic calculation of stage-discharge relationship in the "b" attribute, or specify a Name attribute with a csv file to manually enter the relationship.
TUFLOW HPC - until 2020-01-AB:
Specify a slope larger than zero for automatic calculation in the "b" attribute.
TUFLOW HPC - from 2020-10-AA:
Specify a slope larger than zero for automatic calculation of stage-discharge relationship in the "b" attribute, or specify a Name attribute with a csv file to manually enter the relationship.

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