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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 online help for more detailed descriptions of the enhancements to the objects and their methods.
Water User
Multiple Split Return Flows
A new method, Multi Return Fractional Split, is available in the returnFlowSplitCalculation category. This method allows the user to split the Return Flow and send it to as many destinations as is necessary. In other words, a single Water User can be used to model an areas with similar characteristics that may produce more than one return flow. Each return flow can be linked to a different destination in the model. When this method is selected, the Returned Flows multislot is added. This slot can be linked to the Return Flow (or any other series slot) on several different reaches. When a link is created to this slot, a column representing this link is added to the necessary input table slots. This allows the user to have any number of return flows and data only needs to be given for those return flows that are specified by a link to the Returned Flows slot. Information regarding the use of this method is available in the Simulation Object Documentation online.
Return Flow Routing
A new method category called Return Flow routing is available on all Water User objects. The methods available in this category are dependent upon the method selected in the returnFlowSplitCalculation category. Three methods are available to route the either the return flow, the surface or ground water return flows, or any of the multiple split return flows. The impulse response method is the only routing calculation that is used for return flows. If the user needs to route return flows using a method other than impulse response, a separate Reach object must be used. Information regarding the use of the Return Flow Routing methods is available in the Simulation Object Documentation online.
Split Return Flow Fraction/Efficiency
Since the Multi Return Fractional Split method has been added to the returnFlowSplitCalculation category, the previously existing two categories were renamed so that it is apparent that these methods are used to split between surface and groundwater returns. Therefore, Split Return Flow Fraction and Split Return Flow Efficiency have been renamed SW GW Fractional Split and SW GW Efficiency Split, respectively.
Minimum Efficiency Slot
The Minimum Efficiency slot on the Water User object was changed from a Table Slot to a Series Slot. RiverWare automatically extends the time series range on this slot to match the Run Control Dialog. The single value held in the Table Slot is copied to every timestep in the series. So every model should be updated automatically to use the single table slot value for every timestep in the run. However, if the run dates of the model are changed, values for Minimum Efficiency must be input for the new timesteps. This can be done by hand or preferably through a DMI. If your DMI moves the timestep of your model ahead, then it should be modified to add data to the Minimum Efficiency slot. Another approach would be to extend the timeseries range on the Minimum Efficiency slot to include a very large number of timesteps. Then a value could be input on every timestep using the Fill Values command. This will work as long as the time series is expanded to encompass any possible run period.
Minimum Diversion Request
A new slot, Minimum Diversion Request, has been added to all methods in the Diversion and Depletion Request category. If the user has input a value on this slot, the Diversion and Depletion Request methods will make sure that the calculated Diversion Request is at least the Minimum Diversion Request. If however, the calculated Depletion Request is zero, this slot is not used and the Diversion Request is set to zero. The use of this slot is optional.
Impulse Response Slot Reconfiguration
The Lag Coeff slot was reconfigured to display the lag coefficients in rows rather than columns. This happens automatically and should not affect model results.
Evaporation Category
A new Evaporation Calculation category is available on the Reach object. This category is only available when noRouting is selected in the routing method category. The evaporation category contains a default method, which does nothing, and an Inflow Exponent Pan Evap method. This method computes evaporative loss from the reach based on an empirical equation that uses the Inflow raised to an exponent and a pan evaporation coefficient. Details on the specifics of the equation are available in the Simulation Objects Documentation online.
Reach Bank Storage Calculation
Previously, when computing the Bank Storage Return for the first few timesteps, a Routed Flow of zero was used for those timesteps prior to the Start timestep. This was causing volume conservation problems so the method was modified to assume a constant value for Routed Flow, prior to the Start timestep, that is equal to the first calculated value for Routed Flow. However, if the user has input Routed Flow values prior to the Start date, these will take priority and will not be reset.
(Variable) GainLoss Coefficient
The GainLoss Coefficient (or Variable GainLoss Coefficient) is no longer allowed to be -1.0 when a reach is solving upstream. A GainLoss Coefficient of -1.0 means that 100% of the Inflow to the reach is lost. When solving upstream given an Outflow value, it is impossible to determine a unique Inflow value if the GainLoss Coefficient is -1.0. Basically, an infinite number of Inflows could result in the given Outflow because 100% of it is lost before getting to the Outflow. RiverWare now detects this situation and flags an error when it occurs. Models that contain reaches that solve upstream and have a GainLoss Coefficient of -1.0 will abort when run in the new release. The GainLoss value must be changed to any number that is greater than negative 1.0.
Confluence Object
Confluence Solution Direction
A new method category, Confluence Solution Direction, was added to the Confluence object. The default method in this category is Solve Upstream or Downstream. If this method is selected the Confluence will be able to solve either upstream or downstream depending on the knowns and unknowns. The user may also select the Solve Downstream Only method. If this method is selected the Confluence will always solve in a downstream direction. This is useful in rules models where slot priorities may be causing the object to solve in a direction that is not intended.
Power Reservoirs
Power Capacity Slot
A new slot, Power Capacity, was added to the PeakPowerCalc and PeakBasePowerCalc methods. The peak power value will be set in the Power Capacity slot. This represents the power that could be generated at the given operating head if the turbines are fully open. Prior to this release, the peak power value was stored in the Power slot. Now the Power Capacity slot will hold the peak power and the Power slot will contain the actual power produced. This is calculated by dividing the Energy by the timestep length.
Input Energy Adjustment
A new method category, Input Energy Adjustment, was added to all power reservoir objects. The default method, No Energy Adjustment, will do nothing. If the user selects Reduce Input Energy, and the input Energy value exceeds the maximum energy for the given timestep, the Energy value will be reduced to the maximum value and will be flagged Max Capacity.
Input Outflow Adjustment
A new method category, Input Outflow Adjustment, was added to all reservoir objects. The default method, No Outflow Adjustment, will do nothing. If the user selects Reduce Input Outflow, and the input Outflow value exceeds the maximum outflow for the given timestep, the Outflow value will be reduced to the maximum value and will be flagged Max Capacity.
Inline Power Plant Object
An Inline Power Plant Object is now available on the object palette. This object is used to simulate power production on a reach with no storage capabilities. The object has an Inflow and Outflow that are always equal, and a user method to compute Power and Energy based on the flow rate in the reach. Detailed documentation of the Inline Power Object may be found in the Simulation Objects Documentation online.
Revised: 08/02/2021