Environmental Flow Node (Default)
- Jaya Reddy
Analytics
The Environmental Flow Node (EFN) is designed to simulate environmental flow requirements according to a set of rules. These rules are described through a set of actions, that aim to capture the environmental flow requirements at a particular location within the river system. The actions can be used to define both in-stream and overbank water events. However, in the case of overbank watering events, other nodes (such as a loss node or flow split) will be required to remove any water from the river reach.
The EFN provides a means of capturing the shape of flow events that an environmental water manager may wish to create. These definitions of watering patterns are captured as ‘actions’ within the EFN. Two types of actions are available at the EFN. These actions have been designed to capture the commonly defined environmental flow requirements specified in environmental flow studies and water regulations. These actions allow you to construct a flow regime at a location using of a combination of actions. The two types of actions available are:
- Spell based actions allows you to define a period that the flow has a set of desired characteristics. This type of action can be used to specify a range of event types such as baseflows, fish nesting events, and small to large flood events.
- Translucency actions allow you to specify the flow requirements in terms of some other time series, usually the release from a dam based on the inflow of the dam.
By setting a combination of different actions, you can describe a desired flow regime at a given location in the river system using the environmental flow node's feature editor.
How the environmental flow nodes interact with other components of your river system model such as the environmental flow manager (EFM) and resource assessment system is described in the Scientific Reference Guide. The user guide highlights when the node's behaviour will differ depending on if the environmental flow node is used as a stand-alone node or if it is used in conjunction with an EFM and a resource assessment system.
Setting up the EFN
How you setup the environmental flow node will depend on if you are using the node in conjunction with a resource assessment system and environmental flow manager.
Double-click the EFN to open its feature editor, shown in Figure 1. The EFN feature editor allows you to:
- Specify maximum account deduction. Note: this will only impact the model if the EFN is used in conjunction with a resource assessment system and the EFM
- Specify account deduction. Note: this will only impact the model if the EFN is used in conjunction with a resource assessment system and the EFM
- Specify a set of actions that will determine how the environmental flow node tracks events and/or orders water to deliver a particular flow regime. Actions are added by right-clicking on “Actions” and selecting “Add new action”. You can then choose to add a new Spell Based Action or Translucency Action.
Specify maximum account deduction allows you to specify a limit to water debited from the Portfolios specified in the Environmental Flow Manager. If this deduction cap is more than the total volume ordered, the total order is debited. This parameter can be specified as a value or a function. This parameter only applies when the EFN is used in conjunction with the EFM.
By default, the model will account for the volume of EFN orders (on top of the downstream order). Here, the user can specify a function to limit that volume to a maximum, for example: Max(0, Full Requirement—Minimum Constraint), so that the estimate of the minimum amount of water expected before the environmental flow node orders in the system is not included in the account deduction.
Specify account deduction allows users to Specify Account Deduction at the Environmental Flow Node (EFN) using a function. This parameter only applies when the EFN is used in conjunction with EFM. Users can select either "Specify Maximum Account Deduction," "Specify Account Deduction," or both options simultaneously using a function at the Environmental Flow Node. If both "Specify Maximum Account Deduction" and "Specify Account Deduction" are enabled, the account deduction is capped by the value defined in the "Specify Maximum Account Deduction" setting.
Account deduction can be set up at Node or Action Level as shown in Figure 1.
Specify account deduction at node level
Figure 1. Environmental Flow Node
To enable the account deduction at node level, all EFM groups linked to the Environmental Flow Node's actions must have the same portfolio arrangement, with identical priorities and shares. If portfolio arrangements differ across EFM groups, the system will display a message indicating that node-level account deduction cannot be applied. You must either update the EFM groups to have consistent portfolio setups or choose action-level deduction. If portfolios become inconsistent after enabling this setting, a runtime validation error will prevent the model from running until corrected.
Once validated, users can enable the "Specify Account Deduction" option, select "at node level" from the dropdown, and enter the function for water volume deduction. When node-level account deduction is enabled, actions continue to order according to their configurations but the account deduction is based on the function specified at the node level. The deduction volume is distributed across water accounts based on the priority and share of the portfolios and their associated accounts.
In this setup, action-level recorders (e.g., Environmental Flow Manager > Group x > Action y > Portfolio z > Account a > Debited Volume) display NaN since account deductions do not occur at the action level. Instead, the total deducted volume is recorded at the node level using the node-level recorder (e.g., Environmental Flow Node x > Total Debited Volume).
Specify account deduction at action level
To enable account deduction at the action level, portfolios do not need to match across Environmental Flow Manager (EFM) groups. To set this up, enable the "Specify Account Deduction" option, select "at action level" from the dropdown, which will then presents a table listing all the actions associated with an Environmental Flow Node (EFN) within the editor window as shown in Figure 2. Using this table, the user can configure the debiting using a function for individual actions, either for all the actions or only the selected ones as desired. Any actions not configured default to the standard account debiting method.
In this setup, action-level recorders (e.g., Environmental Flow Manager > Group x > Action y > Portfolio z > Account a > Debited Volume) reflect the deductions applied by the specified function for each individual action, portfolio, and account. The node-level recorder (Environmental Flow Node x > Total Debited Volume) captures the total volume deducted across all actions within the node.
Figure 2. Environmental Flow Node Account Deduction at Action Level Menu
Please note that negative debiting is not allowed in these debiting functions. If a function returns a negative value at a given timestep, it will be treated as zero, and no deduction will occur.
Adding an Action
To add an action, you right click on the top action menu item. You can then choose to add either a Spell Based or Translucency Action (Figure 3). You can add multiple actions to a single node. The actions will work together to determine a total requirement for each timestep.
Right clicking on the action title allows you to rename, add/edit note, delete or enable/disable the action.
Figure 3. Environmental Flow Node Actions Menu
Defining a spell-based action
Spell based actions allow you to define the characteristics of a flow event, the pattern of their occurrence, and conditions under which a rule will become active, and order may be made. Flow rules can be made active or inactive dynamically during a modelling run.
Ordering of actions are separated from the observation of actions.
Figure 4. Spell Based Action menu
| Menu Item | Description |
|---|---|
Desired frequency (return interval): | Determines the desired return (or recurrence) interval. In the case where the Environmental Flow Node (EFN) is managed by the Environmental Flow Manager (EFM), the desired frequency is used in the calculation of Antecedent Condition. The Antecedent Condition is used by the manager as part of prioritising events. If the EFN is not managed by the EFM, the node will use the desired frequency to determine if the action should be targeted. |
| Allow orders: | This is enabled by default. If this box is not ticked, then orders will not be placed. The EFN will use the Spell Observer functionality to record successful spells and seasons only. These non-ordering actions are not visible to the Environmental Flow Manager. |
| Allow forcing of spells: | If this box is ticked, the flow node will attempt to force an action without the trigger as spell requirements being met (i.e. it ignores the need for a threshold or direct order trigger). Forcing will occur at the end of a season when there is only the number of required days left. For example, if a 10-day spell is required, forcing will occur in the last 10 days of the season, if the required event has not already occurred within the specified season. When there are multiple spells in a season, the minimum interval between forced spells, and the length of rise and fall phases, as well the difference between min and max travel time are used to determine when the spells are ordered. The "forcing" of Spells functionality uses the count of observed successful spells by the Spell Observer in its decision-making. |
| Number of season failures before forcing | If "Allow forcing of spells" has been selected, the user needs to specify how many unsuccessful seasons the node should experience before it begins forcing the action. Outputs of the Spell Observer will be used to determine the number of unsuccessful seasons. When used with the EFM, orders will only be placed if the EFM has enabled the action. |
| End Spell using a function | If "End spell using a function" is selected, the user can define a Boolean function that returns 1 (True) or 0 (False). The EFN will continue Ordering while the function returns 0 (false) and orders will be cancelled while the function returns value 1 (True). |
| Override Condition | If enabled, the user can choose to override the default method of evaluating Antecedent Condition. This would allow to user to include more advanced ecological response model. See Antecedent Condition in scientific reference guide for more details. |
| Initial condition | This is to initialise the number of successful spells (for start of run) and is only relevant when the flow node is operating independently from an Environmental Flow Manager. The ‘initial condition’ is based on how desired Frequency has been defined. The user specifies the number of successful spells in the period (as used for the Desired Frequency) before the start of the run. The ‘initial condition’ impacts ordering only, not antecedent conditions. |
| Time since last successful spell | This is to initialise Time since last successful spell recorder. It does not impact the value for antecedent conditions. |
| Time since last successful spell in a successful season | This is to initialise Time since last successful season recorder. It also defines the initial value for antecedent conditions. |
The following Note will appear on the interface if the Action is managed by the EFM. "Note: This action is managed by the Environmental Flow Manager. It will decide if targets result in orders. 'Desired frequency' will still be used to determine the Condition."
Spell Ordering Definition
Figure 5. Spell Ordering Definition menu
| Menu Item | Description |
|---|---|
| Season | This period is for ordering the spells required to complete a successful season (this is to specify a season within a year, the year specified has no relevance). You can define a separate period for observation in the Spell Observer set-up. |
| Number of spells in season | An action could include a number of independent spells. If you require multiple spells for a successful season, be sure to set the "Number of spells required for a successful season" in your Spell Observer set up. |
| Minimum interval between ordered spells | This is relevant for any ordered events when the actions require more than one spell in a season. The "Minimum interval between ordered spells" is used to determine when the spells are ordered, but not for spell observation. |
| Spell Start method | You can choose between a Threshold-based method or Direct ordering-based method to order a spell. |
| Threshold | This will be enabled if you choose a Threshold-based Method in your Spell Start setup. Here, you can provide the threshold that the expected flow must equal or exceed for the spell to be triggered. The expected flow at the environmental flow node is the maximum of the Minimum Constraint at the upstream node and the Order at the downstream node. The user can implement a fixed flow rate, a data source or a function to determine Spell Start Threshold. Functions should be evaluated before the Order Phase. |
| Direct Ordering | This will be enabled if a Direct Ordering-based Method is chosen in your Spell Start setup. A Direct Ordering-based method provides an alternative to using a threshold with the option to initiate spell-based actions controlled by function. You can use a function to define Direct Ordering that returns a True (1) or False (0) to indicate whether the spell should be ordered or not. Functions should be evaluated before the Order Phase. |
| Target: | Target flow rate that the Action will order. The user can implement a fixed flow rate, a data source, a function or a flow target table to determine a spell’s Target You can define a separate target for observation in your Spell Observer set-up. |
| Limit target to reference flow | Limit target to reference flow: If enabled, the Target flow rate will be constrained to the Reference flow rate. When turned on, this allows the user to specify a time series, to which the flow requirement (target) will be limited. For example, the without development (natural) flow can be used to limit the flow requirement. |
| Reference flow: | Reference flow can be determined by a single value, a data source, a function or a flow target table. The target flow (full requirement) will be the minimum of either the Target or Reference flow. |
| Minimum spell duration: | This duration is used for ordering a spell. You can define a separate duration for observation in your Spell Observer set-up. |
| Extend spell duration | This allows the ordering to extend more than the minimum duration when possible The user can either always allow or disallow the spell to extend beyond the minimum duration using a binary TRUE (1) or FALSE (0) or use a function to evaluate whether the spell can be extended. The function should evaluate to TRUE (1) or FALSE (2). Spell Success will be determined by the Spell Observer. |
The parameters below in the Spell Ordering Definition screen define the Rise and Fall.
| Method | Days, Rate (ML/d) or Percentage to define a spell’s rise and fall. For more details see /wiki/spaces/SD560/pages/618038371
|
| Rise | Period, rate or percentage at which flow will rise from expected flow (Minimum Constraint) to the flow Target. |
| Fall | Period or rate at which the flow will fall from the Target flow rate to the Fall Target. The rate of fall is only relevant when expected flow (minimum constraint) and downstream order are both less than targeted flows. The fall period will lie within the defined season. There will only be a fall period if a spell is successful, this will be reflected in the Full Requirement. |
| Fall Target | Targeted flow rate to reduce (fall) flow to. This is used to determine the falling limb of the event based on number of days or rate at which flow should fall. However, if the Percentage method is selected, fall target will be ignored. Note: The rise and fall criteria are not considered in determining spell success. |
Spell Observer
The Spell Observer is designed to look for flow events regardless of whether you have ordered an event. This includes:
- The ability to look for events that occur outside the ordering window
- The ability to look for events that are based on the delivery of a specific volume of water during a particular season.
The Spell Observer functionality integrates with the action and changes the ordering behaviour. The interface (Figure. 6) allows you to set the parameters that will determine the success of a spell (and the success of a season). These parameters can also be set via input sets.
The spell Observer does not consider rates of rise and fall when deciding if an event has been successful.
Figure 6. Spell Observer Menu
| Season | This is a period during which the action is to be observed. If the “Use spell ordering season” is unchecked, the user can define the start and end dates of the observation season here. This period can be longer than the ordering period. |
| Use spell ordering season | If this box is checked, then the observer season will match the season defined for ordering on the Spell Ordering Definition Menu. |
| Start target for observation | Target Flow rate for observation. If the “Use spell ordering definition target” is unchecked, the user can define the flow rate here by either using value or function. If a function is used, the value will be set to the value of the function on the first day of the season each year. This target can be smaller than the one defined in the Spell Ordering Definition Menu. |
| Use spell ordering definition target | If the box is checked, then the observer’s Start target for observation will match the target from the Spell Ordering Definition Menu. You won’t be able to check this box (it will be inactive) if the target has been defined as a Flow Table or Data Source or is limited to the reference flow in your Spell Definition Menu. |
| Minimum duration for observation | Minimum duration of the spell for observation. If the “Use spell ordering definition duration” is unchecked, the user can define the duration here by either using value or function. If a function is used, the value will be set to the value of the function on the first day of the season each year. This duration can be smaller than the one defined in the Spell Ordering Definition Menu. |
| Use spell ordering definition duration | If the box is checked, the Observer’s Minimum duration matches the Minimum spell duration defined on the Spell Ordering Definition Menu. |
| End target for observation | This is the flow threshold below which the flow should fall for a certain number of days (Duration below end target) to consider spell to be finished. If “Use start target for observation” is unchecked, the user can define the end target by either using value or function. If a function is used, the value will be set to the value of the function on the first day of the season each year. If the flow does not drop below the end target for observation, the spell will end when the season ends. |
| Use start target for observation | If the box is checked, then “End target for observation” will match the “Start target for observation”. |
| Duration below end target | This is the minimum duration for which the flow must remain below the “End target for observation” for the spell to be considered complete |
The parameters below in the observation screen define the success criteria. A spell is successful when all these criteria are met.
Proportion Required -Target | Proportion of Start target for observation that needs to be achieved to call an event a success. |
Proportion Required -Duration | The proportion of the defined Minimum duration for observation that needs to be achieved to consider a spell successful. |
Proportion Required -Volume | The proportion of total action volume that needs to be achieved to call an event a success. |
Number of spells required for a successful season | The number of spells required to achieve a successful season. Where the “Number of spells required for a successful season” exceeds 1, the season is considered to be successful when the required number of successful spells is met. When a season is deemed to be successful, the antecedent condition resets to one. It will reset to 1 for each subsequent successful spell in the season. |
Translucency Action
This action allows you to define reference relationships where flow would be allowed to pass through a storage or restrictions be placed on extraction in an unregulated system.
Figure 7. Translucency Action Menu
Season: | Period in which action is required (this is to specify a season within a year, the year specified has no relevance). |
| Translucency reference flow: | Flow to be used to determine the targeted flow (and hence the release from storage) – this could be a time series of inflows to the storage. It could also be a function, which allows flexibility in the definition of the flow requirement. |
| Translucency percentage: | The percentage of the reference flow that is required. |
| Start Threshold: | Flow rate threshold to be reached before the action is triggered. |
| End Threshold: | Translucency action will be ended if flow rate falls below this threshold. |
Add or Edit Note
By right clicking on a heading, notes can be added or edited in three levels: (a) Top environmental flow level (e.g. Environmental Flow in Figure 8); (b) Individual Action level (such as Spell Based Action 1, or Translucency Action 1 in Figure 8) and (c) Function button level (any function button such as (1) in Figure 8 in Spell Ordering Definition, or a Spell Observer of a spell based action or any in Translucency action).
In the Note screen shown in Figure 8, you can define the note's properties using three icons; from section (2), add /edit the note in section (3), and delete the note with the bin icon. The selected property icon (i.e., info, warning and critical) will appear beside any items with that note for the information, even when the Note screen is closed.
Figure 8. Add/Edit Note
Note: For functions used in the Environmental Flow Node, if the function is using modelled variables relating to an action, any time of evaluation prior to and including environmental flow prioritisation can be used. If the function is using modelled variable relating to a group (e.g. group enabled or group cost), then environmental flow prioritisation must be selected for time of evaluation, and additionally, the modelled variable date range must be set to current iteration.
EFN Actions in the Feature Table
The parameters of the Environmental Flow Node (EFN) can be reviewed and edited from two separated elements in the Feature Table.
The node-level parameters, including the option to specify a Maximum Account Deduction can be reviewed and edited for all Environmental Flow Nodes using the Environmental Flow element of the Feature Table (Figure 9).
Figure 9. Environmental Flow element in the Feature Table
All Action-level parameters from all Environmental Flow Nodes in one scenario can be triggered from the Environment Flow Actions element of the Feature Table (Figure 10). Spell Based Action or Translucent Action in the left panel can toggle the relevant parameter details in the middle panel.
Figure 10. EFN Actions in the Feature Table
The Environmental Flow Actions in the Feature Table include both Spell Based Actions and Translucency Actions if applicable. All parameters defined in each Spell Based Actions and/or Translucency Actions can be reviewed and edited. Such parameters cover Spell Based parameters (Figure 4), Spell Ordering Definition parameters (Figure 5), Success Criteria (Figure 6), Rise and Fall parameters (Figure 5); and all Translucency Actions parameters(Figure 7).