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Simulation Objects
The following enhancements to the RiverWare simulation objects are described briefly. The user is encouraged to consult the Simulation Objects Documentation in the RiverWare Help for more detailed descriptions of the enhancements to the objects and their methods.
Slope Power Reservoir
Weighting Coefficients Method
In the Weighting Coefficients method, the Segment BW Table has been renamed Partition BW Table and a unique three column block of data now represents the partitions headwater, backwater, and flow relationship. In addition, the method was modified to set the Backwater Elevation equal to the value of the most upstream partition’s backwater elevation. This allows the user to link the Backwater Elevation to an upstream reservoir’s Tailwater Base Value slot.
Power Reservoir Objects
Peak Power Equation with Off Peak Spill
A new power method called Peak Power Equation with Off Peak Spill was added to the Power Calculation Category on the power reservoir objects. This new method uses the standard power equation to calculate power and energy produced for a peaking portion of the timestep using the water power equation. Included also is a calculation of the off peak spill that occurs when the turbines are not operating.
Additional Hydropower Release
A new category called Additional Hydropower Release Calculation was added to the power reservoir objects. It is used to calculate the additional release necessary to meet a hydropower demand. Two methods were added to this category: the default, no-action No Additional Release method and the Meet Hydropower Load method. Both methods are dependent on having the Phase Balancing or Operating Level Balancing flood control method selected. In addition, this category is dependent on having the Peak Power Equation with Off Peak Spill power calculation method selected. The Meet Hydropower Load method is used by the U.S. Army Corp of Engineers - Southwestern Division to calculate the additional hydropower release necessary to meet a hydropower load. The methods in this category are executed from the HydropowerRelease() predefined rule function.
Load Calculation
A new category called Load Calculation was added to the power reservoir objects. The category is dependent on having the Meet Hydropower Load method selected (see above). In this new category there are seven new methods: No Method, Input Load, Annual Load, Monthly Load, Periodic Load, Seasonal Load and Seasonal Load Time. The selected method in this category is executed at the beginning of each timestep to calculate the desired energy (load) to be generated for the timestep.
Distribution Canal
Storage Calculation
A new method category, Storage Calculation, has been added to the Aggregate Distribution Canal object. If selected, the Input Change in Storage method allows the user to specify when, and at what rate, the canal fills and drains. Between fill and drain dates, the distribution canal will mass balance to track the storage. It is assumed that storage will remain constant and the flows in the canal should be such that storage is maintained. Evaporation and other losses are removed from the canal outflow.
Evaporation from Storage
A new method, Evaporation from Storage, has been added to the Aggregate Distribution Canal object. There is only one user method available, Input Evaporation. The Input Evaporation method allows the user to specify evaporation in a periodic slot. In order to maintain storage (and it is assumed that storage is kept constant except when filling/draining) flows through the canal must be large enough to account for evaporation. Any evaporation is removed from the canal outflow when in the mass balance calculation.
Pipeline Object
Pipeline Hydraulics
The Pipeline object has been enhanced to track the head and head loss associated with pressurized pipe flow. Head loss is computed based on the Hazen-Williams formula.
Thermal Object
Regulation Calculation
The simulation modeling of an ancillary service, voltage regulation, has been improved in two ways. First, regulation is checked for consistency with power generation and hydro capacity (MW): power + regulation <= hydro capacity. If necessary, regulation is reduced to satisfy this constraint. Second, several warning messages have been added. In the course of this work, several relatively small bugs in the simulation calculation of values on the thermal object were detected and corrected.
New Objects: Pipe Junction and Inline Pump
Two new objects have been added to the RiverWare Object Palette, the Inline Pump and Pipe Junction. These objects are intended to be used with the Pipeline object to model a pipeline distribution network. The Inline Pump object is intended to model a booster pump station which adds head and computes the energy consumed. The Pipe Junction object simulates the split or junction of pressurized pipe flow.
Table Interpolation Error and Warning Messages
The table interpolation warning and error messages have been enhanced to increase clarity and to supply more information about the variables involved. Information is now given about the table, the timestep, and the value used in the interpolation. All information is given in user units.
Water Quality / Salinity Enhancements
The well-mixed salinity calculations were enhanced on the following objects: Reaches, Aggregate Reaches, Aggregate Diversion Sites, Confluences, Reservoirs, Bifurcations and Stream Gages.
The Reach and Aggregate Reach objects were enhanced to solve in an upstream direction (when Outflow Salt Concentration is known), and for Local Inflow Salt Concentration (when both Inflow and Outflow Salt Concentration are known). Prior to this release, the Reach and Agg Reach could only solve in the downstream direction.
The Reservoir object has been enhanced to solve in both the upstream and downstream direction. Also, a new user-selectable solution method was added. In addition to the existing default method that solves given a weighting factor, a new method has been added to use the Huen or predictor-corrector solution approach.
On each of the objects mentioned above, slots were added to hold the salt mass data as well as salt concentration data. Essentially, each salt concentration slot (i.e. Inflow Salt Concentration, Diversion Salt Concentration, etc.) now has a corresponding salt mass slot.
Revised: 01/05/2024