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 Extreme dryDryMedianWet
Ecological watering objectivesAvoid damage to key environmental assetsEnsure ecological capacity for recoveryMaintain ecological health and resilienceImprove and extend healthy and resilient aquatic ecosystems

Management objectives

  • Avoid critical loss of threatened species
  • Maintain key refuges
  • Avoid irretrievable damage or catastrophic events
  • Support the survival and growth of threatened species and communities including limited small scale recruitment
  • Maintain deiverse habitats
  • Maintain low flow river and floodplain functional processes in sites and reaches of priority assets
  • Enable growth, reproduction and small-scale recruitment for a diverse range of flora and fauna
  • Promote low-lying floodplain-river connectivity
  • Support medium flow river and floodplain functional processes
  • Enable growth, reproduction and large-scale recruitment for a diverse range of flora and fauna
  • Promote higher floodplain-river connectivity
  • Support high flow river and floodplain functional processes
Management actions
  • Water refugia and sites supporting threatened species and communities
  • Undertake emergency watering at specific sites of priority assets
  • Use carryover volumes to maintain critical needs
  • Water refugia and sites supporting threatened species and communities
  • Provide low flow and freshes in sites and reaches of priority assets
  • Use carryover volumes to maintain follow-up watering
  • Prolong flood/high-flow duration at key sites and reaches of priority assets
  • Contribute to the full-range of in-channel flows
  • Use carryover to provide optimal seasonal flow patterns in subsequent years
  • Increase flood/high-flow duration and extent across priority assets
  • Contribute to the full range of flows including over-bank
  • Use carryover to provide optimal seasonal flow patterns in subsequent years
Key goalDamage avoidanceCapacity for recoveryMaintained health and resilienceImproved health and resilience

Assumptions

The following assumptions are made when EDM is configured in Source:

  • Water requirements are not additive: environmental water is not consumed and as such every individual flow rule water requirement can use the same water in accounting for the success of a flow rule being met;
  • Flow rules can be co-dependent: A flow rule can be conditionally contingent on another flow rule also being met;
  • Flow rules should only be attempted if their requirements are likely to be met: The EDM determines the daily demand, however before passing the demand for this day, the EDM checks to see if the total water required to complete the rule is available; and
  • The highest priority water demand is for flow rules which have commenced but not yet completed. If a flow rule has started to be met, then the continuation of meeting this flow rule requirement has precedence over commencing water ordering to meet a new flow rule.

Flow rules

The EDM  provides a means of capturing prescriptive descriptions of water patterns that the environment requires. These definitions of watering patterns are captured as ‘flow rules’ within the EDM and many combinations of flow rules can be prescribed for a single supply point. The four types of flow rules presented in the EDM have been designed to capture the most commonly defined environmental flow requirements specified in environmental flow studies and water regulations. These environmental demand rules allow you to construct a collective environmental water requirement by using combinations of environmental demand rules. These are:

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Rules can be made active or inactive during a modelling run using Disable in the rule's contextual menu.

Forecasting

The basic approach to determining the water order is to consider the collection of flow rules and determine how much water is required for a given day to meet these rules. As water is not consumed by the EDM, the water order is simply the difference between the calculated water required and the forecast flow at the extraction point on the future delivery day.The EDM allows two forecasting periods, a short term and a medium term. This approach is to reflect real world water management decision making, whereby, depending on the size of the catchment, river operators can generally make a very accurate prediction of the likely flow for the next few days to weeks. After that time the prediction is less accurate. The EDM allows you to define the ‘look ahead’ period, which is the period that can be accurately forecasted. You can use the Expression Editor to define the method of forecasting. The recommended methods for determining the forecast period are to refer to an upstream node with a known travel time.