1D Integrity Tool - Flow Trace

Tool Description

Creates an upstream trace from the selected channel, selecting all upstream network objects in the QGIS map window (network lines and network points). It's recommended to use the flow trace tool in conjunction with the snapping tool and pipe direction tool, as it will highlight any 'breaks' in the network ('breaks' could be caused by snapping or pipe direction errors). In this respect, it can be used initially without any of the processing options turned on.

The flow trace tool is similar to the continuity tool but can limit the checking to sections of the network and adds a long plot visualisation option.

The behaviour of the flow trace can be modified depending on the number of selected channels. See the Processing Options below.

Inputs

The following inputs are used:

• Input Network Lines
• Input Network Points (optional)
• Input Tables (optional)
• Input DEM (optional)

Outputs

The following are output from the tool:

• Output point layer - an output log from the tool identifying potential continuity errors
• Plot window (if the long plot processing option is selected)

Processing Options

The following options are available:

• Flow Area Check - will flag locations where the downstream flow area decreases.
  •  % decrease - only relevant where more than one pipe is entering the downstream junction. Input value will determine the threshold at which the flow area is considered decreasing (e.g. 50% = the downstream flow area has to decrease by at least 50% of all incoming channels). The purpose of this setting is to prevent the amount of unnecessary flagging along 'trunk' pipes that don't increase or decrease in pipe diameter but have small feeder pipes entering it.
• Invert Check - will flag locations where pipes have either an adverse gradient, or where the invert of the outgoing pipe is higher than the invert of the incoming pipe. Will only flag locations where this is true for all incoming and outgoing pipes at any given junction.
• Angle Check - will flag locations where the angle between the incoming pipe and outgoing pipe is less than the given input angle (180 deg is straight). Will only flag locations where this is true for all incoming and outgoing pipes at any given junction.
• Ground Cover Check - requires an input DEM. Will flag locations where the distance between the pipe obvert and ground elevation is less than the input threshold.
• Generate Long Plots - Creates an interactive plotting window with long plots to help visualise the network. The outputs from the continuity check will also be flagged in the long plot. The behaviour of the tool can be modified depending on the number of channels initially selected when the tool is run:
  • One channel selected - will select all upstream network objects and generate a long plot for each unique network branch (e.g. if the pipe system splits upstream of the selected channel, a long plot will be generated for both branches).
  • Two channels selected - will try and connect the selected channels and perform a continuity check only between the selected channels. If channels are not connected, the tool will produce an error message. This is useful to check whether 2 channels are connected and also to focus on a particular branch or section of the network.
  • Three or more channels selected - similar to when two channels are selected, but will generate an extra branch for each extra channel selected (e.g. selecting 3 channels will create 2 branches starting from the most downstream channel). Currently 5 selected channels is the upper limit to stop this from accidentally being triggered for too many branches.

  Note: substantial improvements have been made to the long plot functionality in terms of speed, plot interaction, and behaviour in TUFLOW Plugin Version 3.3. It is recommended to use at least this version.

• Use Previously Selected Channels - this will select the channel lines that were used the previous time the Flow Trace tool was run. This saves the user the effort of manually reselecting the starting line(s) each time they run the tool and allows for quick iterations of the flow trace tool.

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