The main function of the environmental flow manager is to prioritise and activate actions based on a priority purchasing style conceptual model (Figure 3).
Actions are defined at environmental flow nodes and consist of a set of criteria (system conditions), target response, defined success, and condition function. Actions from various EFNs can be grouped and will then be assessed by the environmental flow manager as a set of actions that need to be activated together. Groups are defined at the EFM level allowing actions for multiple assets to be linked.
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). 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 an order) when appropriate. Accounts are not debited until after a managed target response is executed.
Figure 3. Expanded Environmental Flow Manager Conceptual Model: Detailed flowchart for the 'Prioritise and activate/flag actions' box in Figure 2.
Prioritisation of actions/groups within the flow manager
The environmental flow manager sorts groups of actions into ascending priority order by examining the priority values generated for each action by the importance and condition functions.
Priority = (1-Condition) x Importance
If groups have the same priority value, then they are ranked by the importance values, then by condition. The priority of a group is considered to be equal to that of the highest priority action within that group.
Priority can be 0, or even negative, and these are considered a higher priority than any positive value.
The environmental flow manager will not enable an action if it returns an importance value of zero. Groups with any actions with importance > 0 will still be enabled along with any actions in them. To disable a group with multiple actions all actions would need to have importance = 0.
The importance function has no default values and must be specified by the user or else it will be considered to have an importance of 0
The default condition calculation if not specified by the user is EXP(- time since last successful spell/average return interval)
Environmental Flow Prioritsation 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 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.
Enabling of Actions
An action can be disabled at the node and will be ignored by the flow manager, even if it is in a group.
An action will effectively be disabled if the flow manager does not allocate water to its group, however the action will still monitor the flow based on action definition.
Portfolios
Each account within a portfolio can have a balance adjustment specified.
Portfolio Account Balances + Portfolio Balance Adjustments = Balance considered when evaluating against Estimated Costs David Hehir (Deactivated)