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Conjunctive Use
The Conjunctive Use methods are used to model diversions from a different source (for example, groundwater) to supplement surface water diversions.
* None
This is the default user method. It performs no calculations.
There are no slots specific to this method.
* Supplement Diversion
This method functions differently for the three linking structures. There is also a different set of slots for each of the linking structures.
Slots Specific to This Method—No Structure Linking Structure
 Available Supplemental Water
Type: Series Slot
Units: Flow
Description: Represents the amount of water available to supplement surface water diversion
Information:  
I/O: Required input; however, it can by set through a link.
 Consumption
Type: Series Slot
Units: Flow
Description: Total amount of water consumed/used by the Water User
Information:  
I/O: Output only
 Consumption Shortage
Type: Series Slot
Units: Flow
Description: Total water shortage experienced by the crops
Information: This represents the shortage in terms of the water requested for consumption.
I/O: Output only
 Supplemental Diversion
Type: Series Slot
Units: Flow
Description: Amount of water diverted from groundwater for supplemental use
Information:  
I/O: Output only
 Supplement Return Flow
Type: Series Slot
Units: Flow
Description: Amount of return flow from the supplemental water
Information: Calculated by the same method that calculates return flow from surface diversions.
I/O: Output only
 Supplemental Use Delivery
Type: Series Slot
Units: Flow
Description: Amount of supplemental water received by the Water User
Information: For the No Structure case, this is always equal to the Supplemental Diversion.
I/O: Output only
 Supplemental Use Request
Type: Series Slot
Units: Flow
Description: Amount of supplemental water requested
Information:  
I/O: Optional; If not input, it is set to the lower value of Diversion Shortage or Maximum Supplement Request.
 Total Applied Water
Type: Series Slot
Units: Flow
Description: Total amount of water available for consumption/use by the water user
Information:  
I/O: Output only
 Total Return Flow
Type: Series Slot
Units: Flow
Description: Sum of the Return Flow and the Supplement Return Flow
Information: This value is split into surface and groundwater components if a method is selected in the Return Flow Split category.
I/O: Output only
Slots Specific to This Method—Sequential Linking Structure
 Consumption
Type: Series Slot
Units: Flow
Description: Total amount of water consumed/used by the Water User
Information:  
I/O: Output only
 Consumption Shortage
Type: Series Slot
Units: Flow
Description: Total water shortage experienced by the crops
Information: This represents the shortage in terms of the water requested for consumption.
I/O: Output only
 Supplemental Diversion Priority
Type: Table Slot
Units: None
Description: Integer value which represents the Water User’s priority in supplemental water rights
Information: A low integer value indicates a high priority.
I/O: Required input
 Supplement Return Flow
Type: Series Slot
Units: Flow
Description: Amount of return flow from the supplemental water
Information: Calculated by the same method that calculates return flow from surface diversions.
I/O: Output only
 Supplemental Use Delivery
Type: Series Slot
Units: Flow
Description: Amount of supplemental water received by the Water User
Information:  
I/O: Output only
 Supplemental Use Request
Type: Series Slot
Units: Flow
Description: Amount of supplemental water requested
Information:  
I/O: Optional; if not input, it is set to the lower value of Diversion Shortage and Maximum Supplement Request.
 Total Applied Water
Type: Series Slot
Units: Flow
Description: Total amount of water available for consumption/use by the water user
I/O:  
 Total Return Flow
Type: Series Slot
Units: Flow
Description: Sum of the Return Flow and the Supplement Return Flow
Information: This value is split into surface and groundwater components if a method is selected in the Return Flow Split category.
I/O: Output only
Method Details  
For both linking structures, Supplemental Use Request is set by the following equation:
(Maximum Supplement Request slot values are set by the Max Supplemental Request method.)
If the default linking structure is active, Supplemental Diversion is set by the following equation:
Supplemental Use Delivery is then set equal to Supplemental Diversion.
However, if the sequential linking structure is active, Supplemental Diversion is a slot on the Agg Diversion Site and therefore, is calculated there. The Agg Diversion Site then sets Supplemental Use Delivery on each Water User based on the Supplemental Diversion and the Supplemental Diversion Priority of each Water User. This is explained in more detail on the Agg Diversion Site object.
The following calculations are then performed regardless of the linking structure selected:
The Supplement Return Flow is then calculated by the method selected in the Return Flow category. For example, if the Fraction Return Flow method is selected, Supplement Return Flow is the product of Supplemental Use Delivery and the Fraction Return Flow. If the Variable Efficiency method is selected, the efficiency is recalculated based on the Total Applied Water. Return Flow and Depletion are then recalculated for the new Efficiency value. Supplement Return Flow is calculated by the following equation:
Consumption and Consumption Shortage are then computed.
Finally, compute the Total Return Flow, as follows:
• If the Return Flow is linked or the Supplement Return Flow is linked, the Total Return Flow is zero; both slots are linked so the flows go elsewhere.
• If the Return Flow is linked but the Supplement Return Flow is not linked, the Total Return Flow is equal to the Supplement Return Flow.
• If the Return Flow is not linked and the Supplement Return Flow is linked, the Total Return Flow is equal to the Return Flow.
• If neither Return Flow nor the Supplement Return Flow is linked, the Total Return Flow is the sum of Return Flow and Supplement Return Flow.
When the Water User is an element of a sequential Agg Diversion Site, the Outgoing Available water is set to the computed Total Return Flow. This determines how much water is available for downstream elements.
* Supplement Diversion including Soil Moisture
This method allows supplemental diversions when also modeling Soil Moisture. As a result, you must be using both the Irrigation Requests with Soil Moisture and Proportional Shortage with Soil Moisture, or Variable Efficiency with Soil Moisture method.
Note:  This method is available for any of the following conditions:
• On a standalone Water User
• On an element of a No Structure Agg Diversion Site
• On an element of a Sequential Agg Diversion Site
It is not available on a water user on a Lumped Agg Diversion Site.
See “Irrigation Requests with Soil Moisture” for a diagram of the use of Soil Moisture slots.
Slots Specific to This Method
 Available Supplemental Water
Type: Series Slot
Units: Flow
Description: Represents the amount of water available to supplement surface water diversion
Information:  
I/O: This value is required for the method to solve. It is usually propagated across a link.
 Consumption
Type: Series Slot
Units: Flow
Description: Total amount of water consumed/used by the Water User
Information:  
I/O: Output only
 Consumption Shortage
Type: Series Slot
Units: Flow
Description: Total water shortage experienced by the crops
Information: This represents the shortage in terms of the water requested for consumption.
I/O: Output only
 Consumptive Use from Supplemental
Type: Series Slot
Units: Flow
Description: Consumed water from the Supplemental Diversion
Information:  
I/O: Output only
 Irrigated Area
Type: Series Slot
Units: Area
Description: Surface area of the land to be irrigated
Information:  
I/O: Specified according to the selected method in the Irrigation Acreage and Evapotranspiration Rates category; see “Irrigation Acreage and Evapotranspiration Rates”.
 Maximum Soil Moisture
Type: Scalar
Units: Length
Description: Depth of water that the soil can hold.
Information:  
I/O: Required input
 Minimum Efficiency
Type: Series Slot
Units: Fraction
Description: Minimum amount of consumed flow per unit diverted flow
Information: Expressed as a fraction.
I/O: Required input
 Soil Moisture
Type: Series Slot
Units: Volume
Description: This slot tracks the volume of soil moisture water in the soil at each timestep in the run.
Information: For the initial timestep, this slot must be valid. If this slot is not input, it is computed as the Maximum Soil Moisture times the Irrigated Area at the initial timestep. That is, the soil moisture starts full.
I/O: Typically output for run timesteps.
 Supplemental Diversion
Type: Series Slot
Units: Flow
Description: Amount of water pumped from groundwater or diverted for supplemental use.
Information:  
I/O: Input, output, or set by a rule.
 Supplemental Flow to Soil Moisture
Type: Series Slot
Units: Flow
Description: Portion of the supplemental flow that goes to the soil moisture.
Information: This is only positive if Supplemental Diversion is set (input or rules) to a value larger than Supplemental Use Request and less than the infiltration limit.
I/O: Output only
 Supplemental Request Fraction
Type: Series with Periodic Input
Units: Fraction
Description: Fraction of the remaining demand that should be met with supplemental water.
Information: If not specified, it is assumed to 1.0.
I/O: Optional input as either a series or periodic relationship.
 Supplement Return Flow
Type: Series Slot
Units: Flow
Description: Amount of return flow from the supplemental water
Information:  
I/O: Output only
 Supplemental Runoff
Type: Series Slots
Units: Flow
Description: Amount of applied supplemental water that runs off the fields directly due to max infiltration limits.
Information: If the Supplemental Runoff slot is linked to a slot on another object it is not included in the total Return Flow. If the Supplemental Runoff is not linked, the Supplemental Runoff is included as part of the total Return Flow.
I/O: Output only
 Supplemental Use Delivery
Type: Series Slot
Units: Flow
Description: Amount of supplemental water received by the Water User
Information: For the No Structure case, this is always equal to the Supplemental Diversion.
I/O: Output only
 Supplemental Use Request
Type: Series Slot
Units: Flow
Description: Amount of supplemental water requested
Information:  
I/O: Optional; If not input, it is set to the lower value of Diversion Shortage or Maximum Supplement Request.
 Total Applied Water
Type: Series Slot
Units: Flow
Description: Total amount of water available for consumption/use by the water user
Information: It is computed as the sum of Delivered Flow, Excess Effective Precipitation Flow and Supplemental Use Delivery.
I/O: Output only
 Total Return Flow
Type: Series Slot
Units: Flow
Description: Sum of the Return Flow and the Supplement Return Flow
Information: This value is split into surface and groundwater components if a method is selected in the Return Flow Split category.
I/O: Output only
Method Details  
The following equations are executed from the dispatch method (this applies to a standalone or No Structure water user). This method is not available on a sequential Agg Diversion Site, but the soil moisture methods above can be used.
If the Proportional Shortage with Soil Moisture method is selected, efficiencyTemp is set to the Minimum Efficiency.
If the Variable Efficiency with Soil Moisture method is selected, efficiencyTemp is set to the computed efficiency on the slot.
If Maximum Supplement Request is in use and valid:
Otherwise
Since some water has already been applied, compute the new infiltration limit.
If Supplemental Diversion is not specified (Input or set by a rule),
Otherwise, the specified Supplemental Diversion is used.
Compute any Supplemental Diversion that runs off due to the infiltration limit, as follows:
Compute a temporary variable representing the supplemental flow that infiltrates into the soil, as follows:
Next, compute the supplemental use delivery as follows:
If the Variable Efficiency with Soil Moisture method is selected, recompute the efficiencyTemp as the new
When the Proportional Shortage with Soil Moisture method is selected, efficiencyTemp continues to be the Minimum Efficiency.
Compute the initialSupplementReturnFlow as follows. This is the amount that would become return flow regardless of soil moisture.
Calculate consumed supplemental flow as follows:
Calculate remaining available for soil moisture as follows:
Calculate the new limits on soil moisture refill including the flow to fill the soil moisture and the new infiltration limit, as follows:
Calculate the supplemental flow that fills the soil moisture, as follows:
Determine the new Soil Moisture volume, as follows:
Calculate final Supplemental Return Flow.
If the Supplemental Runoff slot is linked to another object, it is not included in the total Return Flow:
Otherwise, the Supplemental Runoff is not linked, the Supplemental Runoff is included as part of the total Supplemental Return Flow:
Compute Consumption and Consumption Shortage, and set Consumptive Use from Supplemental.
Finally, compute the Total Return Flow, as follows:
• If the Return Flow is linked or the Supplement Return Flow is linked, the Total Return Flow is zero; both slots are linked so the flows go elsewhere.
• If the Return Flow is linked but the Supplement Return Flow is not linked, the Total Return Flow is equal to the Supplement Return Flow.
• If the Return Flow is not linked and the Supplement Return Flow is linked, the Total Return Flow is equal to the Return Flow.
• If neither Return Flow nor the Supplement Return Flow is linked, the Total Return Flow is the sum of Return Flow and Supplement Return Flow.
When the Water User is an element of a sequential Agg Diversion Site, the Outgoing Available water is set to the computed Total Return Flow. This determines how much water is available for downstream elements.
Revised: 11/11/2019