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QGIS SWMM Junctions Set Attributes: Difference between revisions

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== Introduction ==
This tool sets SWMM junction attributes 'Ymax' (maximum depth), 'Ysur' (maximum surcharge depth), and 'Apond' (area of ponding). The junction attributes are set based on generic rules, and individual nodes may need to be modified.<br>
This tool supports in-place editing if selected in the QGIS processing window.
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<ol>
<li>'''Input layer:''' The existing junctions layer that willto be updated. To only update the fields of some of the layers' features, select the desired ones and tick on 'Selected features only'.
<li>'''Selected features only:''' If node(s) in the junctions layer have been selected using the 'Select Features' tool, this option will become available. If checked on, the tool will only update the selected node(s).
<li>'''Input Subcatchments [optional]:''' The subcatchments layer(s) that the node(s) receive flow from.
<li>'''Input Inlet Usage Layers [optional]:''' The input inlet usage layer(s) that the node(s) are connected to.
<li>'''Input BC Connection Layers [optional]:''' The BC connection layer(s) that connect the node(s) to the 2D domain.<br>
<li>For information on the other input parameters, refer to the <u>[[QGIS SWMM Junctions Set Attributes#Recommended Settings|Recommended Settings]]</u> section.
<li>'''JunctionAtts:''' Determines the location and filename of the output junctions layer.
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'''Note:''' If 'Edit Feature In-Place' is selected, the tool does not require the 'Input layer' or the 'JunctionAtts' parameters as the tool will override the existing junctions file with the updated attributes.
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[[File:set_attributes_dialogJunctions_Set_Attributes_Dialog_d.png]]
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=== Recommended Settings ===
 
The recommended settings for junctions within the 2D domain dependsdepend on whether the node receives flow from a subcatchment and whether and how the node is connected to the 2D domain. <br>Below is a description of the input parameters and their recommended values.
'''Note:''' It is recommended that Ymax be set to 0.0 for all junctions. SWMM will set Ymax to highest soffit of connected conduits.
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'''Junction nodes receiving subcatchment flows:'''<br>
The recommended settings allow any discharges unable to be conveyed through the node to immediately enter the 2D domain. These discharges are reported as flooding by SWMM.<br>
::*Ysur = 0.0 (forced)
::*Apond = 0.0 (forced)
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<brol>▼
<li>'''General Options:'''
:; Maximum Depth Option (Ymax):
::* Set to 0.0:&nbsp; Initializes the Ymax for all junction nodes to 0.0. This option may be overwritten by the parameters set in the 'Nodes connected to 2D with inlets (underground pipe network)' section.
::* Leave as is:&nbsp; Leaves the Ymax value as is for all junction nodes. This option only applies if using 'Edit Feature In-Place'.
:; Nodes receiving subcatchment flows option (if connected to 2D):
::* Based on options selected below:&nbsp; Parameters set in the following sections will be applied.
::* Set Apond = 0.0; Ysur = 0.0 (overwrites options below):&nbsp; Forces subcatchment outlets to use 0.0 for Ysur and Apond (turns off ponding). When ponding is off, node surcharging is reported as 'flooding' to SWMM and is immediately transferred to the 2D domain.
 
<li>'''Nodes connected to the 2D without inlets (through embankment culvert):'''
'''Junction nodes not receiving subcatchment flows:'''<br>
: '''Ysur:'''&nbsp; Sets the surcharge at nodes connected to the 2D with inlets. Recommended value is 0.0.
It is recommended to allow ponding (set Apond >0). This will allow the head in the node (including pressure head) as a water level. If the water level in the node exceeds the water level in the 2D domain, there will be a flow from the 1D domain to 2D domain.<br>
: '''Apond:'''&nbsp; Set to the approximate area of the 2D cells associated with the 1D/2D BC culvert connections layer(s). A larger area may improve stability, but may artificially attenuate discharges.
▲<br>
 
*<li>'''Junction nodesNodes connected to 2D with aninlets inlet(underground pipe network):'''<br>
:; Maximum depth (Ymax) option (overwrites general setting):
:When nodes are connected through an inlet, either Ysur (surcharge depth) or Apond (area of ponding) can be used to allow the pressure head to exceed Ymax (by default highest adjacent conduit soffit). Using a positive area of ponding may enhance stability. When used, Apond should represent the manhole shaft or a small area. A larger area may enhance model stability but may artificially attenuate discharges. If Apond is non-zero, Ysur is ignored.<br>
::* Set to inlet elevation - node elevation:&nbsp; Sets the Ymax value to the inlet elevation minus the node elevation.
:*Ysur = 0.0, if ponding otherwise higher than expected depths to prevent flooding.▼
::* Use global option:&nbsp; Sets the Ymax value based on the parameters set in the 'Global Options' section.
:*Apond = Manhole area
▲:* '''Ysur:'''&nbsp; =Set to 0.0, if using ponding. otherwiseOtherwise, set to higher than expected depths to prevent flooding.
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: '''Area of ponding:'''&nbsp; Set to the approximate area of the 2D cells associated with the Inlet Usage connections layer(s).
 
*<li>'''JunctionNodes nodeswithout connected toa 2D withconnection a(underground HX boundary (nopipe inletnetwork):'''<br>
:FloodWhen a node is not connected to the 2D, flood losses wouldwill be lost from the model resulting in mass losses and inaccurate results. PreventTo byprevent allowingthis, allow ponding (option 1) or makingmake surgethe elevationsurcharge depth high (option 2).<br> ▼
:When nodes are connected through an HX boundary such as culverts through an embankment, it is recommended to set Apond (area of ponding) to the approximate area of connected cells. A larger area of ponding may improve stability but may artificially attenuate discharges. This will depend on the model cell size. Generally, a typical value is chosen that is reasonable for most of the connections and any significantly larger or smaller structures can be modified on an individual basis. <br>
:; Option #1: ▼
:*Ysur = 0.0
::* Surcharge depth:&nbsp; Set to 0.0.
:*Apond = Typical area of connected 2D cells (higher values may aid stability).
::* Area of ponding:&nbsp; Set to some positive value.
:or; Option #2:▼
::* Surcharge depth:&nbsp; Set to a value higher than any expected depth in the model.
::* Area of ponding:&nbsp; Set to 0.0.
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=== Example ===▼
*'''Junctions not connected to 2D domains:'''<br>
▲:Flood losses would be lost from the model resulting in mass losses and inaccurate results. Prevent by allowing ponding or making surge elevation high.<br>
▲:Option #1:
::*Ysur = higher than expected node depths
::*Apond = 0.0
▲:or Option #2:
::*Ysur = 0.0 (ignored)
::*Apond = (positive number)
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{{Video|name=Animation_Junctions_Set_Attributes_01c.mp4|width=1236}}
 
▲=== Example ===
The following example videos demonstrate junction nodes not receiving subcatchment flows and connected to 2D with a HX boundary (no inlet).<br>
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Save to an existing GeoPackage:
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{{Video|name=Animation_Junctions_Set_Attributes_01a.mp4|width=1235}}
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Using the 'Edit FeaturesFeature In-Place' tool:
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{{Video|name=Animation_Junctions_Set_Attributes_02aAnimation_Junctions_Set_Attributes_02c.mp4|width=12351236}}
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