• InfoWorks ICM

Setting 2D flood types

Assign 2D flood types to nodes in a 2D zone in order to couple them to the 1D sewer network.


Tutorial resources

These downloadable resources will be used to complete this tutorial:

Set_2D_Fld_Types.icmt

Step-by-step guide

2D nodes are used in 2D simulations to model the exchange of water between the 1D sewer system and a 2D zone. When modelling the 1D-2D surface interaction, node ground levels can vary greatly from ground model data, resulting in inaccurate flows and instability. Node ground levels, element ground levels, or node locations may need to be changed. In this example, one potential solution is tried. Always consider what is most appropriate for the specific model and its purpose.

  1. For this example, open the transportable database Set_2D_Fld_Types.icmt, and then copy it to the database.
  2. In the Database, double-click 1D/2D Sewer Model to open it on the GeoPlan.

The InfoWorks ICM interface, with the model for this example copied to the Database and open on the GeoPlan.

The 2D zone is already imported and a 2D mesh is generated. Now, couple the 1D sewer network by setting 2D flood types:

  1. In the GeoPlan, select the 2D zone.
  2. From the Selection menu, click Select objects in selected polygons to select everything within the 2D zone.

In the Selection menu, Select objects in selected polygons selected and highlighted in red.

  1. While pressing the CTRL key, from the Windows toolbar, expand the Grid windows drop-down and select New nodes window.

On the GeoPlan, everything within the 2D zone highlighted in green, and in the Windows toolbar, the Grid windows drop-down expanded, with New nodes window selected and called out.

This grid now displays all nodes within the 2D zone.

Next, locate the Flood type column:

  1. Right-click the grid and select Find column.
  2. In the Find column grid dialog box, expand the Columns drop-down, and select Flood type.

The nodes grid window, with all nodes in the 2D zone listed, and the Find column grid dialog box, with Flood type selected in the Columns drop-down.

  1. Right-click the Flood type column heading and select Sort on selected columns descending.
  2. While pressing the SHIFT key, select all fields with a value of Stored.
  3. Right-click the selection and select Current cell(s) value > Set new value(s) for cell(s).

In the nodes grid window, Flood type column, all values of Stored selected, and in the shortcut menu, Current Cell(s) Value selected, with Set new value(s) for cell(s) selected in the flyout.

  1. In the New Cell Value popup, select 2D.

The New Cell Value popup, with 2D set as the value, highlighted in red.

  1. Click OK.

For a 2D flood type, the exchange of water between the 2D manhole and the mesh is calculated using the weir equation, assuming a weir crest level at the node ground level and crest length equal to the node shaft circumference.

  1. In the nodes grid window, find or scroll to the Flooding discharge coefficient column.

A flooding discharge coefficient equivalent to the weir discharge coefficient is specified for the node.

  1. Ensure that the rows have a default value of 0.5. If not, populate the values.

The next step is to assign the Gully 2D flood type to the nodes which are currently set as Lost. First, however, the head-discharge relationship that these nodes will follow needs to be defined:

  1. From the Grid windows drop-down, select New links window.

From the Windows toolbar, the Grid windows drop-down, with New links window selected.

  1. At the bottom of the grid window, scroll to the Head discharge tab. This is currently populated with a screen head discharge table.
  2. In the Head discharge ID column, select the cell below Screen.
  3. Enter an ID of “Typical Cover” to generate a new table entry.

In the Grid window, the active Head discharge tab called out with a red arrow, and in the Head discharge ID column, the new Typical Cover entry created and highlighted in red.

  1. In the far-left cell of the same row, double-click to open the table Properties window.
  2. In the Head discharge power table field, click More ().

In the Head discharge window, enter the following values into the table:

  1. In Row 1, set the Head to -0.5 and the Discharge to -2.
  2. In Row 2, set the Head to 0 and the Discharge to 0.
  3. In Row 3, set the Head to 0.5 and the Discharge to .001.

In the Properties window for Typical Cover, the More (…) button called out, and in the Head discharge window, values entered in the first three rows of the table for this example.

Negative values in this table represent flooding onto the 2D zone, and positive values represent flow entering the sewer system. This table has been set up to allow minimal flow into the node from the surface, while allowing a relatively free discharge of flow (flooding) onto it. This would be most appropriate for foul or sanitary sewers, or where the gully connections are represented in detail.

  1. Click OK.

Now, assign the 2D Gully flood type to nodes currently set as Lost:

  1. Return to the nodes grid window.
  2. In the Flood type column, use the SHIFT key to select all fields with a value of Lost.
  3. Right-click the selections and select Current cell(s) value > Set new value(s) for cell(s).
  4. In the New Cell Value popup, select Gully 2D.
  5. Click OK.

For a gully 2D flood type, the exchange of water between the 2D manhole and the mesh is calculated using a head discharge relationship.

  1. Scroll to the Head discharge table column, which should be populated with the Typical Cover table that was just created.

In the nodes grid window, the Head discharge table column populated with the Typical Cover table.

Finally, update the outfall nodes:

  1. In the nodes grid window, right-click the Node type column heading and select Sort on selected column(s) descending, so that the outfall nodes appear at the top of the list.
  2. Select the Outfall values.
  3. Right-click the selection and click Current cell(s) value > Set new value(s) for cell(s).
  4. In the New Cell Value popup, select Outfall 2D.
  5. Click OK.

In the nodes grid window, Node type column, Outfall values selected and highlighted in red, and in the New Cell Value dialog box, Outfall 2D selected as the new value, with OK selected.

The 2D outfall is used to allow the exchange of water between an outfall and a 2D element. These outfalls will now interact with the 2D mesh, rather than the flow being lost from the system.

  1. Click Validate to make sure there are no errors in the network.
  2. Click OK.
  3. Click Commit changes to database to save the changes.
  4. Add a comment, such as "Added connections for 1D nodes to 2D".
  5. Click OK.