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Simulation Objects
Power Reservoirs
Unit Power allows negative unit energy
On the power reservoirs, the Unit Power method was modified to allow the user to set (via input or rules) negative Unit Energy values to represent times when the unit is consuming energy. In this case, the Unit Turbine Release is set to zero.
Conversion of series slots to Periodic
On the reservoirs, the following slots were converted from Series Slots to Periodic Slots:
• Irrigated Area Loss Rate
• K Factor
• Meadow Area Loss Rate
• Pan Ice Switch
When you first load your model, if you are using these slots, a series of warning message will be posted to diagnostics, for example:
“SLOT: Reservoir.K Factor: Trying to convert former slot type ("SeriesSlot") to new slot type ("PeriodicSlot")."
You must re-entered the data into these slots where applicable. This is especially true for the Pan Ice Switch; previously, the value would default to 0 if not input, now the value MUST be input. A single 0.0 in the periodic slot is sufficient if only 0 is required.
Periodic Net Evaporation Method
A new evaporation method, Periodic Net Evaporation was added to the reservoirs’ Evaporation and Precipitation category. Periodic Net Evaporation computes the gross evaporation from the reservoir and then subtracts out components of evaporation that would have occurred if the reservoir had not been built. This is the net evaporation and is set in the Evaporation slot. Each area of the submerged reservoir is separate including: river, streamside, terrace, and any remaining areas.
Single Value Seepage method
A new seepage method, Single Value Seepage, was added to the reservoirs’ Seepage Calc category. The Single Seepage Value method sets the seepage through the face of the dam equal to a scalar value.
Pan Evaporation method
A new method, Pan Evaporation, was added to the reach’s Evaporation Calculation category. This method models evaporation based on the pan evaporation rate, the surface area of the reach and a pan evaporation coefficient.
For more information, see Pan Evaporation in Objects and Methods.
Reach Seepage
In the Head Based Seepage and One Timestep Seepage Lag methods, positive seepage is limited to be less than or equal to the inflow to the reach. A bug occurred when the reach re-dispatched with a larger inflow. The seepage was not reverting to its original value, but was using the constrained value. A slot "Seepage from Previous Timestep Conditions" was added to hold the lagged seepage. Then, the seepage is reset to this value when necessary.
Groundwater Storage - Evaporation category and methods
A new category, Evaporation, was added to the groundwater storage object.
This category contains two methods: No Evaporation and Wetted Sand Evaporation. No Evaporation is the default method and performs no calculations. The Wetted Sand Evaporation method computes the evaporation that occurs from the wetted sand of the shallow groundwater.
Revised: 08/02/2021