By default, the geographic extent of the created geometry contains the entire HEC-ResSim elements in the selected network. To modify the default extent for a geometry dataset:

  1. From the HEC-ResSim main window (Figure 4.1), from the Toolbar (Figure 4.1), select the Water Quality Extent and Regions (WQ Extent/Regions) tool . With the tool active in the map window the mouse pointer changes to .


  1. To use the WQ Extent/Regions tool to modify the extent of the selected geometry dataset, click and hold the left mouse button, drag a polygon to surround the network elements of interest (excluding the elements to remove from the extent). The mouse acts as a drawing tool to create the polygon highlighting the area to create the new extent. Release the mouse to select the elements within the selection polygon. Selected elements display in yellow (e.g., Lake Sonoma in Figure 4.19).



Figure 4.19 – 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 following layers are automatically included (listed in order of the top layer to the bottom layer): WQ Reach Cells, geometry extent elements, HEC-RAS cross-sections, and the HEC-ResSim network. Review Section 2.7 for more information regarding map layers.
In order to view the selected geometry without the WQ Reach Cells (so that highlighted elements are more apparent in the map window schematic), from the HEC-ResSim main window (Figure 4.1), from the View menu, select Layers (Figure 2.25). The Layer Selector window (Figure 4.20) opens. From the Layers tree, uncheck the checkbox for the WQ Reach Cells layer (Figure 4.20). The geometry reach cells layer is no longer displayed in the map window (Figure 4.21).

Figure 4.20 – 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 the elements that were missed by the selection polygon, select the WQ Extent/Regions tool (Figure 4.21), hold the Shift keyboard key and left-click the element in the map window to add it as a selected elements.
To modify the extent of the geometry, right-click the selected elements and a shortcut menu opens (Figure 4.22). Three techniques are available for modifying list of elements in the extent. To replace the entire existing extent, to add a selected element to an existing extent, or to remove and upstream or downstream element from an existing extent.
When making changes to the extent using the shortcut menu options (Figure 4.22), an internal check tests to make sure the extent is contiguous. If not, an Error message (Figure 4.23) opens asking the user to make them contiguous.

Figure 4.22 – HEC-ResSim Main Window – Extent Shortcut Menu Options


Figure 4.23 – 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 (Figure 4.22). Network elements removed or excluded from the extent are displayed in the map window schematic in grayed out (e.g., Lake Sonoma in Figure 4.24).

Figure 4.24 – Network Elements Excluded from Extent (e.g., Lake Sonoma)

  1. A Warning message dialog opens (Figure 4.25). Click OK (Figure 4.25), to close the Message dialog and update the list of elements in the Extent tab for the selected geometry dataset (Figure 4.18). Alternatively, click Cancel (Figure 4.25), to close the Message dialog without changing the elements in the geometry dataset.



Figure 4.25 – Warning Message Dialog
Instead of replacing all of the elements in the extent, element(s) can be added to the extent or removed from the extent using the following shortcut menu options.

Add a Network Element to the Extent


To add selected element(s) to the extent:

  1. From the map window schematic, right-click the element of interest (or left-click to select additional elements while holding down the Shift keyboard key, then right-click) the WQ Extent/Regions tool's shortcut menu (Figure 4.22) opens. From the shortcut menu, under Extent, click Add to (Figure 4.22).


  1. The Extent message dialog opens (Figure 4.26). The Extent message dialog lists the selected element(s) ("Sub Domains") that were added to the extent. Click OK to close the Extent message dialog opens (Figure 4.26).



Figure 4.26 – Extent – Warning Message – Adding Sub Domains

Remove Upstream or Downstream Elements from the Extent


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

  1. From the map window schematic right-click the element of interest, the WQ Extent/Regions tool's shortcut menu (Figure 4.22) opens.


  1. From the shortcut menu (Figure 4.22), under Extent, click Remove Upstream Elements from (Figure 4.22). The selected element (and any other elements listed in hydrologic order above the selected element) is immediately removed from the extent.


  1. Alternatively, from the shortcut menu (Figure 4.22), under Extent, click Remove Downstream Elements from (Figure 4.22). The selected element (and any other elements listed in hydrologic order below the selected element) is immediately removed from the extent.


Once the extent contains the desired contiguous list of HEC-ResSim elements, from the Geometry Editor (Figure 4.17), from the Extent tab (Figure 4.17), click Apply (Figure 4.17) to save edits. Alternatively, click OK, to save edits and close the Geometry Editor (Figure 4.17).