Draw and Assign Diversions Command

A diversion is an element with two outflows, main and diverted, and one or more inflows. Inflow comes from other elements in the basin model. If there is more than one inflow, all inflows are added together before computing the outflows. A diversion can be used to represent weirs or pump stations that divert flow into canals or off-stream storage. The diversion element includes optional properties for limiting the amount of diverted flow.

In GeoHECHMS, diversions can be defined by either drawing or assigning nodes on the Map View using the following commands:

Drawing/Assigning Diversions

The Draw/Assign Diversions command is used to manually draw/assign multiple diversion nodes on the Map View, one after another, until completed.

Follow the steps below to use the Draw/Assign Diversions command:

1. From the Input ribbon menu, select the Diversions dropdown menu and then choose the Draw/Assign Diversions command.
   
2. The following dialog box(s) will be displayed.

Drawing Diversions

Drawing Diversion Nodes

The Draw Diversion Nodes section is used to draw diversions on the Map View using nodes. To draw diversion nodes, follow the steps below:

1. From the Draw Diversion Nodes section, click the [Draw] button, and the dialog box will temporarily disappear.
   
2. The status bar (shown under the Map View) will prompt you to place a diversion on the Map View. Click on the Map View to place the diversion.
   
3. Following placement of a diversion, the Draw Diversions dialog box will be redisplayed, and the Diversion nodes read-only field will change from Not Drawn to Drawn.
   Notes:
   • To position the diversions more accurately, use the mouse roller wheel to zoom into a specific location.
   • The Snap Mode option can be enabled to cause the drawn diversion to snap to the nearest HEC-HMS element.

Assigning Diversions

Selecting Diversion Nodes

The Select Diversion Nodes section can be used to manually assign multiple nodes on the Map View as diversions. To assign diversion nodes, follow the steps below:

1. From the Select Diversion Nodes section, click the [Pick] button and the dialog box will temporarily disappear.
   
2. The status bar (shown under the Map View) will prompt you to select a diversion node from the Map View. Click on the previously drawn diversion node on the Map View to select it.
   
3. Following the selection of a diversion node, the Assign Diversions dialog box will be redisplayed, and the Diversion nodes read-only field will change from Not Selected to 1 Selected.
   

Diversion Specifications

This section is common to both the Draw Diversions and Assign Diversions dialog boxes and is used to specify the diversion ID for each drawn/assigned diversion. The user can assign these IDs either manually or automatically using some predefined formats.

Follow the steps below to assign diversion IDs to the diversions:

1. If a diversion was drawn/assigned while the Diversion ID radio button option was selected, the user can manually enter the diversion ID in the corresponding field as shown below.
   
2. Alternatively, the user can enable the Auto-name diversion ID radio button option to automatically name every newly drawn/assigned diversion as per the user’s predefined naming formats as shown below.
   The different naming formats present in the Auto-name diversion ID option are as follows:
   • Diversion ID prefix: This option allows a prefix to be added to the start of the diversion ID.
   • Diversion ID digits: This option permits specification of a set number of digits to use for the diversion ID. For example, using 3 digits causes the diversion ID to be of the format 001, 002, etc.
   • Next available diversion ID: This entry defines the next element ID number to be used.
   • Diversion ID increment: This entry defines the increment to use when numbering elements. The default value is 1.
   • Diversion ID suffix: This option allows a suffix to be added to the end of the diversion ID.
   • Diversion ID preview: This entry provides a preview of the diversion naming specification defined above.
3. After providing the Diversion ID, press the [Enter] key or click the [Apply] button.
   

Note that if the auto-name option is enabled and the user returns to the dialog box, the [Apply] button will be disabled since the just drawn/assigned diversions have already been named and created.

Assign Invert Elevation

This section is common to both the Draw Diversions and Assign Diversions dialog boxes and allows the user to assign an invert elevation to the diversion using a terrain model. Define this section before drawing diversions so that invert elevations can be assigned.

To assign an invert elevation, the Terrain elevation source dropdown combo box supports the following surface types:

The user can also apply an elevation offset to raise or lower the diversion by the specified amount by checking the Apply elevation offset checkbox. On selecting this checkbox, the entry field next to it becomes available for entering an elevation offset value. A negative offset value will lower the diversion by the specified amount.