A Confluence node represents a natural join in a river system (a tributary or a reconnection of an anabranch). Both inflows combine into a single effluent without any loss or delay. You describe the arrangement of the natural system as one of (Figure 1):

Neither inflow is regulated;
One inflow is regulated; or
Both inflows are regulated.

Figure 1. Confluence node (ordering configuration)

The behaviour of a confluence node depends on the number of branches that are regulated. If there is only one regulated branch, the unregulated branch behaves like an inflow node. If both branches are regulated, orders are processed according to the method specified under Regulated Ordering Methodology (as shown in Figure 1):

Constraint based - Specify a priority for each branch; or
Harmony based - Use an expression to calculate how the order will be split.

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.

Note: You may have to select the regulated link and then re-select the unregulated link before the forecasting controls become visible.

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. Note that the confluence forecast model ignores any upstream nodes on the unregulated branch. This means that any upstream inflow node forecast models are ignored in the confluence node forecast calculation.

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