Difference between revisions of "QGIS SWMM Junctions Set Attributes"

Latest revision as of 15:46, 26 August 2024

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.
This tool supports in-place editing if selected in the QGIS processing window.

Usage

This tool, Junctions - Set Attributes, can be found in the QGIS processing toolbox panel under TUFLOW >> SWMM. To open the Processing Toolbox panel, navigate to 'Processing' in the menubar and select 'Toolbox'.

Parameters

Input layer: The existing junctions layer to be updated.
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).
Input Subcatchments [optional]: The subcatchments layer(s) that the node(s) receive flow from.
Input Inlet Usage Layers [optional]: The input inlet usage layer(s) that the node(s) are connected to.
Input BC Connection Layers [optional]: The BC connection layer(s) that connect the node(s) to the 2D domain.
For information on the other input parameters, refer to the Recommended Settings section.
JunctionAtts: Determines the location and filename of the output junctions layer.

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.

Recommended Settings

The recommended settings for junctions within the 2D domain depend on whether the node receives flow from a subcatchment and whether and how the node is connected to the 2D domain. Below is a description of the input parameters and their recommended values.

General Options:
Maximum Depth Option (Ymax)
Set to 0.0: 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: 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: Parameters set in the following sections will be applied.

Set Apond = 0.0; Ysur = 0.0 (overwrites options below): 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.
Nodes connected to the 2D without inlets (through embankment culvert):
Ysur: Sets the surcharge at nodes connected to the 2D with inlets. Recommended value is 0.0.

Apond: 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.
Nodes connected to 2D with inlets (underground pipe network):
Maximum depth (Ymax) option (overwrites general setting)
Set to inlet elevation - node elevation: Sets the Ymax value to the inlet elevation minus the node elevation.

Use global option: Sets the Ymax value based on the parameters set in the 'Global Options' section.
Ysur: Set to 0.0 if using ponding. Otherwise, set to higher than expected depths to prevent flooding.

Area of ponding: Set to the approximate area of the 2D cells associated with the Inlet Usage connections layer(s).
Nodes without a 2D connection (underground pipe network):
When a node is not connected to the 2D, flood losses will be lost from the model resulting in mass losses and inaccurate results. To prevent this, allow ponding (option 1) or make the surcharge depth high (option 2).
Option 1
Surcharge depth: Set to 0.0.

Area of ponding: Set to some positive value.
Option 2
Surcharge depth: Set to a value higher than any expected depth in the model.

Area of ponding: Set to 0.0.

Example

Using the 'Edit Feature In-Place' tool:

Up
Back to TUFLOW QGIS Plugin Main Page

@@ Line 1: / Line 1: @@
 == Introduction ==
-This tool sets SWMM junction attributes 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 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.
 <br><br>
@@ Line 13: / Line 13: @@
 <ol>
-<li>'''Input layer:''' The junctions layer that will be updated. To only update the fields of some of the layers' features, select the desired ones and tick on 'Selected features only'.
+<li>'''Input layer:''' The existing junctions layer to be updated.
+<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>'''Input BC Connection Layers [optional]:''' The BC connection layer(s) that connect the node(s) to the 2D domain.
 <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.
@@ Line 22: / Line 23: @@
 '''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.
 <br><br>
-[[File:Junctions_Set_Attributes_Dialog_a.png]]
+[[File:Junctions_Set_Attributes_Dialog_d.png]]
 <br><br>
 === Recommended Settings ===
-The recommended settings for junctions within the 2D domain depends on whether the node receives flow from a subcatchment and whether and how the node is connected to the 2D domain. <br>
+The recommended settings for junctions within the 2D domain depend on whether the node receives flow from a subcatchment and whether and how the node is connected to the 2D domain. 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.
-<br><br>
-'''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)
-<br>
-'''Junction nodes not receiving subcatchment flows:'''<br>
-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>
 <br>
+<ol>
+<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.
-*'''Junction nodes connected to 2D with an inlet:'''<br>
+<li>'''Nodes connected to the 2D without inlets (through embankment culvert):'''
-: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>
+: '''Ysur:'''&nbsp; Sets the surcharge at nodes connected to the 2D with inlets. Recommended value is 0.0.
-:*Ysur = 0.0, if ponding otherwise higher than expected depths to prevent flooding.
+: '''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.
-:*Apond = Manhole area
-<br>
-*'''Junction nodes connected to 2D with a HX boundary (no inlet):'''<br>
+<li>'''Nodes connected to 2D with inlets (underground pipe network):'''
-: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>
+:; Maximum depth (Ymax) option (overwrites general setting):
-:*Ysur = 0.0
+::* Set to inlet elevation - node elevation:&nbsp; Sets the Ymax value to the inlet elevation minus the node elevation.
-:*Apond = Typical area of connected 2D cells (higher values may aid stability).
+::* Use global option:&nbsp; Sets the Ymax value based on the parameters set in the 'Global Options' section.
-<br>
+: '''Ysur:'''&nbsp; Set to 0.0 if using ponding. Otherwise, set to higher than expected depths to prevent flooding.
+: '''Area of ponding:'''&nbsp; Set to the approximate area of the 2D cells associated with the Inlet Usage connections layer(s).
-*'''Junctions not connected to 2D domains:'''<br>
+<li>'''Nodes without a 2D connection (underground pipe network):'''<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>
+When a node is not connected to the 2D, flood losses will be lost from the model resulting in mass losses and inaccurate results. To prevent this, allow ponding (option 1) or make the surcharge depth high (option 2).
-:Option #1:
+:; Option 1:
-::*Ysur = higher than expected node depths
+::* Surcharge depth:&nbsp; Set to 0.0.
-::*Apond = 0.0
+::* Area of ponding:&nbsp; Set to some positive value.
-:or Option #2:
+:; Option 2:
-::*Ysur = 0.0 (ignored)
+::* Surcharge depth:&nbsp; Set to a value higher than any expected depth in the model.
-::*Apond = (positive number)
+::* Area of ponding:&nbsp; Set to 0.0.
+</ol>
 <br>
-=== Example ===
+== Example ==
-The following example videos demonstrate junction nodes not receiving subcatchment flows and connected to 2D with a HX boundary (no inlet).<br>
 <br>
-Save to an existing GeoPackage:
+{{Video|name=Animation_Junctions_Set_Attributes_01c.mp4|width=1236}}
-<br><br>
-{{Video|name=Animation_Junctions_Set_Attributes_01a.mp4|width=1235}}
 <br>
-Using the 'Edit Features In-Place':
+Using the 'Edit Feature In-Place' tool:
 <br><br>
-{{Video|name=Animation_Junctions_Set_Attributes_02a.mp4|width=1235}}
+{{Video|name=Animation_Junctions_Set_Attributes_02c.mp4|width=1236}}
 <br>