Priority Determination
This category appears only if the Operating Level Balancing method is selected in the Flood Control category.
Methods in this category determine the timing of the priority determination of reservoirs.
None Note: This is not a valid method; an error will be posted if selected.
This is the default method.
End of Prior Timestep, FixedThe reservoirs in the subbasin are given priorities based on their “fullness” at the end of the prior simulation timestep, if in the flood pool at that time. If a reservoir is in the flood pool at the end of the prior timestep, its ending operating level is its priority. If not, its forecast operating level at the end of the balance period becomes its priority. These priorities are used for the entire duration of the flood control method, regardless how much water is scheduled for release from any reservoir in the subbasin during the method’s computations.
When this method is selected, the set of “full” reservoirs on any pass is processed in the order of the predetermined priorities, above. If reservoirs are to be added to the set, the Reservoir Set category (q.v., below) selection must be Reservoirs Starting in or Entering Flood Pool.
Slots Specific to This Method
Forecasted Operating Level
Type: Agg Series Slot
Units: Lengths
Description: There is one column for each reservoir in the subbasin (this is recreated at run initialization). Each column stores the forecasted operating level; that is for the current timestep, the operating level a the end of the balance period. Thus, if the balance period is 4. The value shown on this slot at timestep 1 is the forecasted operating level at timestep t+3 (current plus three timesteps). This operating level is from the first pass only.
Information: This slot is invisible but can be viewed in the computational subbasin’s Special Results details on the Model Run Analysis tool; see Model Run Analysis—Special Results Details Dialog in USACE‑SWD Modeling Techniques.
I/O: Output only
Links: Not linkable
RA ended yesterday’s simulation at level 4.8, RB at 8.1, RC at 4.4. RA is forecast to be at level 5.6 at the end of the balance period, RB at 10.0, and RC at 4.9. The priorities are assigned as follows: RA: 5.6, RB 10.0, RC 4.4. On each pass, the reservoirs will be processed (given a chance to consume channel space) in this order: RB, RA. RC will not be processed, unless the Reservoir Set category selection is Reservoirs Starting in or Entering Flood Pool, in which case, it will be processed on the last pass if it takes on tandem storage to bring it into the flood pool.
End of Balance Period, VariesFlood control considers only the reservoirs’ forecast operating levels at the end of the balance period. Those priorities are recomputed at each pass of the algorithm, based on the latest forecast storages, which take into account proposed release schedules and proposed tandem storage. At the beginning of each pass, the entire subbasin’s set of reservoirs is considered. The last pass is demand-driven, so that if reservoir A’s new releases change the state of empty space in a way that might affect reservoir B, reservoir B is reprocessed.
Slots Specific to This Method
Forecasted Operating Level
Type: Agg Series Slot
Units: Lengths
Description: There is one column for each reservoir in the subbasin (this is recreated at run initialization). Each column stores the forecasted operating level; that is for the current timestep, the operating level a the end of the balance period. Thus, if the balance period is 4. The value shown on this slot at timestep 1 is the forecasted operating level at timestep t+3 (current plus three timesteps). This operating level is from the first pass only.
Information: This slot is invisible but can be viewed in the computational subbasin’s Special Results details on the Model Run Analysis tool; see Model Run Analysis—Special Results Details Dialog in USACE‑SWD Modeling Techniques.
I/O: Output only
Links: Not linkable
RA ended yesterday’s simulation at level 4.8, RB at 8.1, RC at 4.4. RA is forecast to be at level 5.6 at the end of the balance period, RB at 10.0, and RC at 4.9. The initial priorities are assigned as follows: RA: 5.6, RB 10.0, RC 4.9. On the first pass, the reservoirs will be processed (given a chance to consume channel space) in this order: RB, RA. As soon as RC takes on enough storage to put it above the balance level of a pass, it will be processed. Likewise, the other reservoirs will be reprioritized on each pass, according to their projected levels that result from the projected releases on the prior pass.
Revised: 07/09/2023