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The main function of the environmental flow manager is to prioritise and activate actions based on a priority purchasing style conceptual model (Figure 3).

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The EFM prioritises the actions (or groups of actions) based on the condition of the asset (1-condition) multiplied by a user defined importance weighting (i.e. (1-condition) x importance). and importance. Environmental flow nodes keep track of the condition associated with the actions. The condition is calculated by default by dividing the average desired return interval by the number of days since last success (with values limited to maximum of 1). This can be replaced by a user specified condition function. The importance weighting is calculated using a user defined function, which allows flexibility in the way the events are prioritised and coordinated. 

The Environmental Flow Manager will then determine whether there is sufficient water available to meet each group's needs in priority order, decreasing the amount available to each subsequent priority as the group above reserves water. To do this, the EFM steps through the ranked action list and compares the cost of the action (ie. the volume of water required to deliver the action) to the available water in the portfolios of accounts that can be accessed by the action. If enough water is available, the EFM will commit the water required to meet the estimated cost (i.e. subtracts the volume from the water available), so that the committed water is not available for actions with lower importance. The environmental flow manager flags the action as active to the EFN. The environmental flow manager does not execute actions, it gives permission to the environmental flow node to evaluate the criteria of the flagged (committed) rule and initiate a target response (eg. place orders) when appropriate. Accounts are only debited after orders are made (either order debit or use debit depending on your accounting system). 

Figure 3. Expanded Environmental Flow Manager Conceptual Model: Detailed flowchart for the 'Prioritise and activate/flag actions' box in Figure 2.

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1. Update functions with time of evaluation of Environmental Flow Prioritisation
2. Decide if the flow manager will run based on the decision point configuration
3. Calculate Portfolio balances
4. Run the main prioritisation loop

The condition is calculated by default by dividing the average desired return interval by the number of days since last success (with values limited to maximum of 1). This can be replaced by a user specified condition function. The importance weighting is calculated using a user defined function, which allows flexibility in the way the events are prioritised and coordinated.

1. Update functions with time of evaluation of Environmental Flow Prioritisation

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foreach (group in Groups To Prioritise)
{
  if (group.IsActivelyDelivering) 
  {
      group.EnabledByEFM = true
      CommitEstimatedCostToPortfolios(group)
      Groups To Prioritise.Remove(group)
  }
}

CommitEstimatedCostToPortfolios will distribute the estimated cost of a group across portfolios so that the Portfolio.AvailableWater is reduced. This distribution works in a similar way to distribution of water user orders to supply points. That is, the cost will be split across the highest priority portfolios first in the share percentages specified in the portfolio configuration. Lower priority portfolios will only be used once higher priority portfolios have no available water.

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// sort groups by whether they were enabled by the EFM first, then by priority 
SortGroups(Groups to Prioritise)
 
foreach (group in Groups To Prioritise)
{
   UpdateFunctions()
 
   // TotalPortfolioAvailableWater is the sum of all of the group's portfolios AvailableWater.
   if (group.IsInSeason && group.TotalPortfoliosAvailableWater >= group.EstimatedCost)
   {
      group.EnableByEFM = true
      CommitEstimatedCostToPortfolios(group)
   }
   else
   {
      group.EnableByEFM = false
   }
}

It is important to note a few things in the above psuedo code. First, groups that were enabled the last time the EFM was run will be prioritised before other groups that were not, regardless of priority. Secondly, if a group has no actions that are in season today, they will always be disabled. The ReducePortfoliosByCost function is the same as described above.

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The default condition calculation if not specified by the user is EXP(- time since last successful spell/average return interval)

Environmental Flow Prioritisation Phase

All functions are set by default to evaluate at the start of time step, environmental flow prioritisation phase is an advanced usage. If enabling one group has dependencies on another, the functions will need to be evaluated multiple times during prioritisation, and therefore the time of evaluation in the Environmental Flow Prioritisation phase is indicated. This allows the cost of actions, and hence groups, to be recalculated based on the groups which have already been enabled or disabled. This recalculation occurs each time a group is enabled or disabled.

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