- Neither inflow branch is regulated - no configuration is required as there are no orders;
- One inflow branch is regulated; or
- Both inflows branches are regulated.
Figure 1. Confluence node (ordering configuration)
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| Note: The confluence node adds the upstream minimum and maximum constraints together. |
One regulated branch
If there is only one regulated branch, the unregulated branch behaves like an inflow node.
As there is only one regulated upstream branch, priority setting is not required. In this case, the confluence node can be thought of as acting in a similar manner to an inflow node. As such, the branch which is unregulated needs to have forecasting ability of the inflow arriving, so that orders may be adjusted for the expected inflow. Therefore the confluence node has a forecasting model attached to it (as shown in Figure 1). The forecast model is the same as that available for an inflow node (see Forecasting inflows). However, you cannot choose to use a model based on the current time-step.
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| Note: The confluence forecast model ignores any upstream nodes on the regulated branch. This means that any upstream inflow node forecast models are ignored in the confluence node forecast calculation. |
Figure 1. Confluence node (Single regulated branch)
Both regulated branches
If both branches are regulated, orders are processed according to the method specified under Regulated under Regulated Ordering Methodology (as shown in Figure 1):
- Constraint based (default) - Specify a priority for each branch. Click the cell in the Priority column and edit the value; or
- Harmony based - Use an expression to calculate how the order will be split. - Used to balance the volumes of defined storages on each upstream branch in a defined ratio. You must specify the upstream storage volume for each upstream branch on which to base the harmony operations. These are defined by the Function Editor, so that potentially each branch’s volume can be sourced from multiple storages. You must also specify how to split the upstream orders - using either a table or an expression.
When defining a table that has the proportional relationship on how orders are to be split upstream based on the defined volume of water up each branch for each owner as shown in Figure 2. You can work with the table as follows:
- To add a column, right click on one of the column headings and choose Add Volume. The other menu options will change the columns as shown in Figure 2; and
- To add a row, click on a cell in the last row to edit it. Enter a value and press Enter.
Figure 2. Confluence node, harmony based
The names in the Link column are those you assign to the upstream links. For systems with a single regulated inflow, it is possible to define a method to forecast inflows from the unregulated system. In this situation, you select the row representing the unregulated link, after which you can adjust the Recession Forecast Model controls.
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Note: You may have to select the regulated link and then re-select the unregulated link before the forecasting controls become visible. |
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