Ordering priorities allow users in Source to specify how shortfalls are prioritised between different demands in Source. Previously, Source tried to shortfall all demands equally within the model, this functionality provides a solution to address situations encountered in water resource models such as the following:
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Prioritisation influences how water is taken by water users and how a storage with multiple outlets prioritises releases down the different outlets. A model with prioritisation configured is able to provide information on how water is supplied to users along regulated river reaches between regulating structures.
Principal
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developers
Ordering priorities were implemented for the Victorian government Department of Environment, Water, Land and Planning by eWater with the assistance of Murray Darling Basin Authority and NSW Department of Primary Industries.
Version
Source full version 4.1.1
Assumptions /Overview
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and Dependencies
A rules based ordering system must be active in Source. For a rules based ordering system to operate in Source, the "New rules based ordering system" option must be selected as the ordering algorithm. At least one supply or demand node must be present in the system.
The current behaviour for sharing shortfalls in Source is maintained as the default behaviour (distribute shortfalls equally)
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- Supply Points
- Environmental Demand Nodes
- Minimum Flow Requirements
- Storage Nodes
. This is reflected as all nodes receiving a priority of 1 initially in the priority table
Priorities are assigned in levels of 0 to n, with the lower n level having the highest priority
A priority array is calculated during the order phase which shows the proportion of the total order for all defined priority levels. The sum of this priority array must always equal 1 (within some pragmatic tolerance)
The priority array is calculated during the order phase for each elements minimum order time
The priority array must be kept for order times (0...min order time) at all elements. This should be managed in the ordering recorder much like constraint factors
The priority array at 0 time should be used in the flow array to determine whether a supply point can extract water
Where orders are increased/decreased for
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losses (evaporation, seepage
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) and gains (tributary inflows, rainfall, groundwater
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Then ), then the priority ratios are not changed as these adjustments are assumed to be required to supply the downstream order.
Variables
- n number of priorities specified
- pNode Node priority applies to things which can place orders
- dsOrder(min) ds order at a node at min flow time
- order(min) order propagated upstream at min flow time
- nPriority(n) output array of n priorities for the node
- dsPriority(n) array of n priorities being passed into the node
- sumDSPriorityG sum of dsPriority(n) where n < pNode
- sumDSPriorityGE sum of dsPriority(n) where n <= pNode
- sumDSPriorityL sum of dsPriority(n) where n > pNode
- sumDSPriorityLE sum of dsPriority(n) where n >= pNode
- sumnPriorityG sum of nPriority(n) where n < p
- MinFlowReq minimum flow requirement
- SupplyPointOrderOrder generated by water user and passed to supply point
- dsMainPriority(p) Priorities arriving at a splitter from the main branch
- dsMainOrder Order arriving at a splitter from the main branch
- dsEffPriority(p) Priorities arriving at a splitter from the effluent branch
- dsEffOrder Order arriving at a splitter from the effluent branch
Min Minimum Flow Node
The minimum flow node needs to have a priority assigned to it (pNode) by the user. The priority assigned to the minimum flow requirement can change the proportions of the priorities being passed upstream. There are essentially two scenarios that can occur
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Supply Point
There are essentially four scenarios in how a supply point node can be configured for the rules based-ordering, shown in Table 1. Note that if a Supply Point is selected as groundwater then it should not be part of the ordering network i.e. it should not be allowed to generate orders (this does not appear to happen in the model, maybe more validation for that setting?)
As the Supply Point can extract water from the system we need to consider how the priorities affect both the order phase and the flow phase.
| Anchor | ||||
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Scenario | Allow Order | Extract Water | Notes |
1 | True | True | Standard case |
2 | True | False | Just restrict the extraction in the flow phase – should not be an issue |
3 | False | True | Water will be extracted independently of the priorities |
4 | False | False | Nothing occurs |
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