TUFLOW 1D Channels and Hydraulic Structures: Difference between revisions
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[[File:Section deactivation N R.png | 200px]]
==Calculating a 1d_bc Head-Discharge Curve==
There is no automatic way of creating a Head-Discharge curve for 1d_bc HQ boundaries. However, the condition to be satisfied for a normal depth is the Manning’s equation. So the HQ depth should be set up with elevation and the discharge calculated from Manning’s equation (including Area and Hydraulic Radius for each elevation point) and can be calculated manually in a few steps:<br>
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<li>Set the model up your ESTRY model using a dummy downstream level boundary (e.g. a HQ boundary with no name, an error will be reported however the required check file will have been produced, otherwise any boundary will work) and run the model in test model (-t) so that check files are produced.
<li>From the check folder, open the '''*_1d_ta_tables.csv''' file.
<li>Find the entry for the most downstream cross-section (directly upstream of the 1d_bc HQ point). The '''*_1d_ta_tables.csv''' will contain a table of hydraulic parameters. The K entry highlighted is the cross-section conveyance in m<sup>3</sup>/s and is calculated as: <br><br>
K = 1/n * A * R<sup>2/3</sup><br><br>
Where
* A is the Eff Area
* R is the Radius
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[[File:Ta tables example.png | 800px ]]<br><br>
<li>Determine a representative slope (S), this could be taken from the last two cross-sections.
<li>Calculate the downstream Discharge (this is the same as calculated discharge from Mannings equation): <br><br>
Q = K * SQRT(S)<br><br>
Where:
* S is a representative slope value for the downstream reach.
* K is obtained from the '''1d_ta_tables.csv'''
<li>Use the Elevation (Head) vs Discharge pairs to populate the HQ table.
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