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USACE-SWD Algorithms
Improved Debugging Diagnostics
The following changes were made to the Control Point and Computational subbasin USACE-SWD Flood Control methods for better debugging:
• Unnecessary debugging diagnostics that print the routing coefficients were removed.
• Debugging diagnostics for the target balance level computation were enhanced. This computations a bisection method, so now the diagnostics show the starting conditions and the total empty space to fill. It then prints messages on each iteration in the bisection. Finally, when a target is found, diagnostics are posted showing the storage above the balance level and the final computed share value.
• Formatting of debugging diagnostic messages was improved to show an appropriate level of precision.
Alternative Routing on Subbasin
In some USACE-SWD models, alternative routing is specified on the computational subbasin to modify the routing coefficients used during high (or low) flow events. Previously, to use this method, you had to specify the following methods:
• Reach: Variable Step Response
• Control Points: Compute Aggregate Coefficients
• Computational Subbasin: Compute Aggregate Coefficients
The reach stores the alternative coefficients and is used as the location where the flow conditions are measured. The subbasin and control points compute their coefficients at the beginning of each timestep by aggregating the coefficients from each upstream reservoir to the control point. This limited the dispatching to only use the Variable Step Response method and no other methods.
To allow Variable Step Response for flood control, but a different routing for simulation, a new category and reach was added to the reach: Alternative Routing on Subbasin category and Variable Step Coefficients method. This method allows the Variable Lag Coefficients to exist on the reach for use in the computation of aggregated Control Point coefficients while the actual simulation routing uses an alternative routing method. For more information, see Alternative Routing on Subbasin in Objects and Methods
In addition, on the Control Point, the name of the Temp Routing Coefficients slot was changed to Computed Routing Coefficients. It was also configured to show that it is generated from other data and is read-only. This slot is recomputed in each run so existing models will not be affected unless RPL logic references this lot. For more information, see Compute Aggregate Coefficients in Objects and Methods.
Revised: 08/02/2021