Draw and Assign SA/2D Initial Condition Points Command

Initial conditions consist of flow and stage information at each of the cross sections and elevations for any storage area or 2D flow area defined in the system. Initial conditions can be established in two different ways. The most common way is to enter flow data for each reach and then have the software compute water surface elevations by performing a steady flow backwater analysis. The second method can only be used if a previous run was made. This method allows the user to write a file of flow and stage from a previous run (Restart File), which can then be used as the initial conditions for a subsequent run.

In GeoHECRAS, the SA/2D flow area initial condition points can be either drawn or assigned as nodes using the following commands:

Drawing SA/2D Initial Condition Points

The Draw SA/2D Initial Condition Points command allows the user to manually draw storage area or 2D flow area initial condition points on the Map View.

Follow the steps below to draw the SA/2D initial condition points:

1. From the Input ribbon menu, expand the SA/2D BC Elements dropdown menu, and then choose the Draw SA/2D Initial Condition Points command.
   
2. The Draw SA/2D Initial Condition Points dialog box will be displayed.
   
3. Click the [Draw] button adjacent to the Initial conditions point read-only field.
4. The Draw SA/2D Initial Condition Points dialog box will temporarily disappear, allowing the user to draw the initial condition node inside a SA/2D flow area on the Map View.
5. Once done, the drawn node will be highlighted on the Map View, and the Draw SA/2D Initial Condition Points dialog box will be redisplayed. In addition, the status of the Initial conditions point read-only field will change to Drawn.
   
6. The software automatically names the drawn SA/2D flow area initial condition point as defined in the Initial Conditions Point Specifications section. Note that the Initial conditions point name entry field is editable.
7. Click the [Apply] button, and the SA/2D initial condition point will be created.

Assigning SA/2D Initial Condition Points

The Assign SA/2D Initial Condition Points command allows the user to manually assign existing node(s) from the Map View as SA/2D flow area initial condition points.

Follow the steps below to assign nodes as SA/2D initial condition points:

1. From the Input ribbon menu, expand the SA/2D BC Elements dropdown menu, and then choose the Assign SA/2D Initial Condition Points command.
   
2. The Assign SA/2D Initial Condition Points dialog box will be displayed.
   
3. Click the [Pick] button adjacent to the Initial conditions point read-only field.
4. The Assign SA/2D Initial Condition Points dialog box will temporarily disappear, allowing the user to select an existing node(s) from the Map View.
5. Once done, press the [Enter] key or right-click and select Done from the displayed context menu.
6. The Assign SA/2D Initial Condition Points dialog box will be redisplayed, and the number of selected nodes will be shown in the Initial conditions point read-only field, as shown below.
   
7. The Initial Conditions Point Specifications section is used to name the selected node either manually or automatically. If a single node is selected from the Map View, then the dialog automatically switches to the Initial conditions point name option for naming the selected node individually. Whereas, if multiple nodes are selected from the Map View, then the dialog automatically switches to the Auto-name initial conditions point, prefix option for naming each node as per the defined initial condition point prefix.
8. After naming the initial condition point(s), click the [Apply] button and the software will assign the selected node(s) as SA/2D initial condition point(s).