The Compute Incremental Local Inflows on Subbasin category is used to specify whether the Control Point contains cumulative local inflows that must be disaggregated. Methods allow the user to either disaggregate all cumulative flows at once or forecast the cumulatives then disaggregate. The disaggregation is executed from the Computational Subbasin containing this Control Point. See “Incremental Local Inflows” for details.

The Compute Incremental Local Inflows on Subbasin category contains three methods, None, Compute Full Run Incremental Local Inflows and Compute Forecast Period Incremental Local Inflows methods.

When the Input Local Inflows is selected in the Local Inflow Calc category, the Compute Full Run Incremental Local Inflows becomes available. The new method contains two new slots: Cumulative Local Inflow and Incremental Local Inflow. Data must be input into the Cumulative Local Inflow slots. The computational subbasin will execute the Compute Full Run Incremental Local Inflows method and set the Incremental Local Inflow slots as input. Setting the Incremental Local Inflow slots as input prevents the slot values from being cleared in future model runs when the subbasin is disabled. The computational subbasin will first check that Compute Full Run Incremental Local Inflows method has been selected on all reservoirs and control points in the basin. During the model run, the Compute Full Run Incremental Local Inflows method will copy the value in the Incremental Local Inflow slot and set the Local Inflow slot.

When a forecast method is selected in the Generate Forecast Inflows methods, a new method becomes available within the Compute Incremental Local Inflows on Subbasin category: Compute Forecast Period Incremental Local Inflows. This method contains the Cumulative Local Inflow slot and the Forecasted Cumulative Local Inflow slot. When this method is selected the computational subbasin executes the Compute Forecast Period Incremental Local Inflows method and sets the Local Inflow slots.

This method is the default for the Compute Incremental Local Inflows on Subbasin category and should be selected when local inflow data is not cumulative or the computation of incremental local inflows is not desired.

There are no slots specific to this method.

The Compute Full Run Incremental Local Inflows method is available from the Compute Incremental Local Inflows on Subbasin category on the Control Point. This method is only available if the Input Local Inflows method is selected in the Local Inflow category. The method contains two slots: Cumulative Local Inflow and Incremental Local Inflow. These slots will be accessed by the computational subbasin when executing the Compute Full Run Incremental Local Inflows method. The computational subbasin will use the user input Cumulative Local Inflow value to calculate and set the Incremental Local Inflow slot. The Compute Full Run Incremental Local Inflows method on the control point then copies the results of the calculation in the Incremental Local Inflow slot values to the Local Inflow series slot.

The Compute Forecast Period Incremental Local Inflows method is available from the Compute Incremental Local Inflows on Subbasin category on the Control Point only if the Forecast Local Inflows method is selected in the Local Inflow category and one of the forecasting methods (that is, Geometric Recession or Exponential Recession) is selected in the Generate Forecast Inflows category. If this method is selected, but the control point is not part of a subbasin with the appropriate methods selected, an error will be issued. The method contains two slots: Cumulative Local Inflow and Forecasted Cumulative Local Inflow. These slots will be accessed by the computational subbasin when executing the Compute Forecast Period Incremental Local Inflows method. The computational subbasin will use the user input Cumulative Local Inflow value to forecast and set the Forecasted Cumulative Local Inflow slot.

See “Compute Forecast Period Incremental Local Inflows” for details. See “Forecasting Incremental Local Inflows From Cumulative Flows” in USACE‑SWD Modeling Techniques for USACE‑SWD models.