TUFLOW Message 2365

TUFLOW Message
WARNING 2365 - Exceeded top of HQ curve.

Alternate Message
NA

Message Type
WARNING

Description
Water level at HQ boundary has exceeded the top of the defined stage (H) vs flow (Q) relationship. The HQ boundary automatically creates an stage-discharge relationship to the highest elevation encountered along the boundary.

Suggestions
If a stage-discharge relationship has been defined consider extending this relationship for higher water levels. If a stage-discharge relationship is calculated by TUFLOW by defining a water surface slope, the automatic HQ relationship extends to the highest elevation along the HQ line (the HQ relationship calculated by TUFLOW is outputted to the _2d_bc_tables.csv file).

To extend the level that the HQ relationship is calculated for an automatic HQ boundary there are two options:

• Extend the HQ line to higher grounds.

• The 2d_bc “d” attribute can be used to set the maximum depth of the automatically generated HQ curve (note d is a depth, not an elevation). This option assumes glass walls at the edges of the HQ line, e.g. there is no additional flow area to the sides, it does not take into account the increase in floodplain storage as the water surface level goes up. This might artificially inflate water surface levels immediately downstream and understate the flood extent.

For both suggestions, HQ curve would be automatically extended:

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