Sinks define the elements (i.e., dry wells, wet wells, etc.) where one or more inflows enter, but there are no outflows. Multiple inflows in a sink element are added to determine the total amount of water entering the element. Sinks can be used to represent the lowest point of an interior drainage area or the outlet of the basin model.
In GeoHECHMS, sinks can be defined by either drawing or assigning nodes on the Map View using the following commands:
- Draw Sinks
- Assign Sinks
The Draw/Assign Sinks command is used to manually draw/assign multiple sink nodes on the Map View, one after another until completed.
Follow the steps below to use the Draw/Assign Sinks command:
- From the Input ribbon menu, select the Sinks dropdown menu and then choose the Draw/Assign Sinks command.
- The following dialog box(s) will be displayed.
- Draw Sinks:
- Assign Sinks:
- Draw Sinks:
The following sections describe how to use the Draw/Assign Sinks command and interact with the above dialog box(s).
Drawing Sink Nodes
The Draw Sink Nodes section is used to draw sinks on the Map View using nodes. To draw sink nodes, follow the steps below:
- From the Draw Sink Nodes section, click the [Draw] button, and the dialog box will temporarily disappear.
- The status bar (shown under the Map View) will prompt you to place a sink on the Map View. Click on the Map View to place the sink.
- To position the sinks more accurately, use the mouse roller wheel to zoom into a specific location.
- The Snap Mode option can be enabled to cause the drawn sink to snap to the nearest HEC-HMS element.
- Following placement of a sink, the Draw Sinks dialog box will be redisplayed, and the Sink nodes read-only field will be changed from Not Drawn to Drawn.
Selecting Sink Nodes
The Select Sink Nodes section can be used to manually assign multiple nodes on the Map View as sinks. To assign sink nodes, follow the steps below:
- From the Select Sink Nodes section, click the [Pick] button and the dialog box will temporarily disappear.
- The status bar (shown under the Map View) will prompt you to select a sink node from the Map View. Click on the previously drawn sink node on the Map View to select it.
- Following the selection of a sink node, the Assign Sinks dialog box will be redisplayed, and the Sink nodes read-only field will be changed from Not Selected to 1 Selected.
This section is common to both the Draw Sinks and Assign Sinks dialog box and is used to specify the sink ID for each drawn/assigned sink. The user can assign these IDs either manually or automatically using some predefined formats.
Follow the steps below to assign sink IDs to the sinks:
- If a sink was drawn/assigned while the Sink ID radio button option was selected, the user can manually enter the sink ID in the corresponding field as shown below.
- Alternatively, the user can enable the Auto-name sink ID radio button option to automatically name every newly drawn/assigned sink as per the user’s predefined naming formats as shown below.
The different naming formats present in the Auto-name sink ID option are as follows:
- Sink ID prefix: This option allows a prefix to be added to the start of the sink ID.
- Sink ID digits: This option permits specification of a set number of digits to use for the sink ID. For example, using 3 digits causes the sink ID to be of the format 001, 002, etc.
- Next available sink ID: This entry defines the next element ID number to be used.
- Sink ID increment: This entry defines the increment to use when numbering elements. The default value is 1.
- Sink ID suffix: This option allows a suffix to be added to the end of the sink ID.
- Sink ID preview: This entry provides a preview of the sink naming specification defined above.
- After providing the Sink 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 sinks have already been named and created.
Assign Invert Elevation
This section is common to both the Draw Sinks and Assign Sinks dialog box and allows the user to assign an invert elevation to the sink using a terrain model. Define this section before drawing/assigning sinks so that invert elevations can be assigned.
To assign an invert elevation, the Terrain elevation source dropdown combo box supports the following surface types:
- Elevation grids
- LandXML data
- TIN surfaces
The user can also apply an elevation offset to raise or lower the sink 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 sink by the specified amount.