Georeferencing Sinks

A sink is an element with one or more inflows but no outflows. Multiple inflows are added together 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, the Georeference Sinks command is used to manually georeference each of the sinks to the background base map displayed in the Map View.

The Georeference Sinks command provides the following two options to manually georeference sinks to the desired location:

Follow the steps below to use the Georeference Sinks command:

1. From the Input ribbon menu, expand the Sinks dropdown menu and select the Georeference Sinks command.
   
2. The Georeference Sinks dialog box will be displayed.
   

The following sections describe how to georeference a sink to a desired location and interact with the above dialog box.

Selecting Sink to Georeference

The Select Sink to Georeference section allows the user to select the sink that is to be georeferenced. The user can select the sink from the Sink ID dropdown combo box that lists all the sinks contained within the model. Alternatively, the user can click the [Pick] button to select the sink from the Map View.

After clicking the [Pick] button, the dialog box will temporarily disappear, and a prompt will be displayed on the status bar instructing the user on what to do next. The user can then interactively select a sink from the Map View. Note that the user can select only one sink at a time to georeference.

Upon selecting a sink, the dialog box will be redisplayed, and the Sink ID dropdown combo box updates automatically to match the selected sink.

The user can click the [Clear] button to cancel all the previous selections and redo the entire process.

Snapping Sink to an Alignment Point

If an existing alignment point for the sink exists on the Map View, the Snap to Alignment Point option can be used to snap the sink to the alignment point.

The user can click the [Pick] button to select the alignment point from the Map View. On clicking the [Pick] button, the dialog box will temporarily disappear, and a prompt will be displayed on the status bar instructing the user on what to do next. The user can then interactively select the alignment point from the Map View.

Upon selecting the point, the dialog box will be redisplayed, and the status of the Select alignment point read-only field changes to Selected. Note that the user can select only one alignment point to use for georeferencing.

The user can click the [Clear] button to cancel all the previous selections and redo the entire process.

Once the alignment point has been selected, click the [Snap] button, and the software will snap the selected sink to the alignment point.

Drawing Sink Node on Map View

The Draw on Map View radio button option allows the user to draw a sink node on the Map View to which the selected sink is to be georeferenced. Selecting the Draw on Map View radio button option enables the [Draw] button.

On clicking the [Draw] button, the Georeference Sinks dialog box will temporarily disappear, and a prompt will be displayed on the status bar instructing the user on what to do next. The user can then draw the sink node on the Map View. Once the sink node is drawn, the dialog box will be redisplayed and the selected sink will be georeferenced to the drawn node.

Assigning Sink Elevation

The Assign Sink Elevation section uses the elevation data to assign an invert elevation to the georeferenced sink. The user should define the data in this section before georeferencing sinks. Alternatively, the user can use the Assign Sink Elevations command to assign invert elevations to the already drawn sinks. Refer to this article in our knowledge base to learn more about the Assign Sink Elevations command.

For assigning elevation data, the Terrain elevation source dropdown combo box supports the following surface types:

The following surface types are unsupported:

The user can also apply an elevation offset to raise or lower the selected sink by the specified amount by checking the Apply elevation offset checkbox option. On selecting this checkbox, the user can enter the offset value in the entry field next to Apply elevation offset checkbox option.