By default, the geographic extent of the created water quality geometry encompasses all the elements in the selected ResSim network. To modify the default extent for a geometry dataset:

  1. From the ResSim main window, select the Water Quality Extent and Regions (WQ Extent/Regions) tool from the Toolbar. When the tool is active, the mouse pointer changes to a drawing tool .
  2. To modify the extent of the selected geometry dataset using the WQ Extent/Regions tool, click and hold the left mouse button. Then, drag the mouse to create a polygon that surrounds the network elements you wish to include, excluding those you want to remove from the extent. The mouse will act as a drawing tool to create the selection polygon , highlighting the desired area for the new extent.
  3. Release the mouse button to select the elements within the drawn polygon. The selected elements will be highlighted in yellow (e.g., Lake Sonoma in the HEC-ResSim Main Window – Water Quality Extent and Regions Tool – Extent Selection Polygon Example ).


HEC-ResSim Main Window – Water Quality Extent and Regions Tool – Extent Selection Polygon Example
Tip: By default, when the geometry dataset is displayed in the map window, the WQ Reach Cells and HEC-RAS cross-sections are automatically included. For more information on map layers, refer to Water Quality Layers and Layer Properties. 
To view the selected geometry without the WQ Reach Cells (making the highlighted elements more visible in the map window schematic), follow these steps: 

  1. From the ResSim main window, go to the View menu and select Layers. This will open the Layer Selector window ( Layer Selector – Unselect WQ Reach Cells Layer).

  2. In the Layer Selector window (Layer Selector – Unselect WQ Reach Cells Layer), uncheck the box next to the Reach Cells layer in the Layers tree.

  3. The geometry reach cells layer will no longer be displayed in the map window, making the selected elements more apparent (as shown in HEC-ResSim Main Window – Water Quality Extent and Regions Tool – Elements Selected Example).



Layer Selector – Unselect WQ Reach Cells Layer


Figure 4.21 – HEC-ResSim Main Window – Water Quality Extent and Regions Tool – Elements Selected Example
To include additional elements that were missed by the selection  polygon, select the WQ Extent/Regions tool, then hold the Shift key on your keyboard and left-click on the element in the map window to add it to the selected elements. 

To modify the geometry extent, right-click on the selected elements. A shortcut menu will open (see Figure 4.22). Three options are available for modifying the list of elements in the extent:

  1. Replace the entire existing extent.
  2. Add a selected element to the existing extent.
  3. Remove an upstream or downstream element from the existing extent.

When making changes to the extent using these shortcut menu options (HEC-ResSim Main Window – Extent Shortcut Menu Options), an internal check ensures the extent remains contiguous. If the extent becomes discontinuous, an error message (Example Error Message – Extent Must Be Connected) will appear, prompting the user to resolve the issue and make the extent contiguous.

 

HEC-ResSim Main Window – Extent Shortcut Menu Options


Example Error Message – Extent Must Be Connected

Replace Existing Extent


To replace the entire list of elements in the existing extent:
From the WQ Extent/Regions tool's shortcut menu (Figure 4.22), under Extent, click Replace. Network elements that are removed or excluded from the extent will be displayed in the map window schematic in a grayed-out state (e.g., Lake Sonoma in Network Elements Excluded from Extent (e.g., Lake Sonoma)).

 

Network Elements Excluded from Extent (e.g., Lake Sonoma)

A Warning message dialog opens (Warning Message Dialog). Click OK, to close the Message dialog and update the list of elements in the Extent tab for the selected geometry dataset. Alternatively, click Cancel, to close the Message dialog without changing the elements in the geometry dataset.


Warning Message Dialog
Instead of replacing all the elements in the extent, individual element(s) can be added or removed using the following shortcut menu options.

Add a Network Element to the Extent


To add selected element(s) to the extent:

  1. In the map window schematic, right-click the element of interest (or left-click additional elements while holding the Shift key, then right-click). This will open the WQ Extent/Regions tool's shortcut menu.
  2. From the shortcut menu, under Extent, click Add to.
  3. The Extent message dialog will open  (Extent – Warning Message – Adding Sub Domains), displaying a warning about adding subdomains. It lists the selected element(s) ("Sub Domains") that have been added to the extent.
  4. Click OK to close the Extent message dialog.



Extent – Warning Message – Adding Sub Domains

Remove Upstream or Downstream Elements from the Extent

To remove all elements upstream or downstream of a selected element:

  1. In the map window schematic, right-click the element of interest to open the WQ Extent/Regions tool's shortcut menu.
  2. From the shortcut menu, under Extent, select Remove Upstream Elements from. The selected element (along with any elements listed in hydrologic order above it) will be immediately removed from the extent.
  3. Alternatively, from the shortcut menu, under Extent, select Remove Downstream Elements from. The selected element (along with any elements listed in hydrologic order below it) will be immediately removed from the extent.

Once the extent contains the desired contiguous list of elements on the ResSim network, click Apply in the Geometry Editor's Extent tab to save the changes. Alternatively, click OK to save the edits and close the Geometry Editor.