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Species specific water requirements

Flow assessment

Generalised and process models

Fish resilience through movement


In intermittent streams, the resilience of resident fish populations is influenced by the capacity of fish to recolonise waterholes following periods of extended no flow. Water resource development and instream structures can impact on the capacity for fish to move. The basic approach of this model is to identify a period when habitat is contracted to waterholes (no flow for 365 days), and then to report on the duration of time from this point of further contraction until flow adequate to allow movement (magnitude and duration) has been achieved. The purpose of the model is to allow comparison in the number and severity (duration) of extended periods of stress (from dry period end until water hole reconnection).

Water requirements

Fish resilience in intermittent streams is heavily influenced by their ability to recolonise following periods of no flow.

Model purpose

The purpose of the model is to analyses long times series of modelled flow to determine if the risk to the ability of fish to recolonise following long dry spells is adversely affected by proposed water resource development (represented in the modelled flow).

Development context

This model was developed to support the Queensland Department of Environment and Resource Management’s ecological risk assessment for Water Resource Plan (WRP) reviews.

Spatial application

This model and its default parameters are applicable to intermittent lowland streams where the resilience of a fish population is contingent on their ability to recolonise following long dry periods.

Model description

Ecohydrological rules

Suitability scores for fish resilience are defined according to the following flow parameters:

  • Suitability score = 1 when wetlands have water (defined by the time since an overbank connection event and the time required for a wetland to dry).
  • Suitability score = 0.5 during periods following a wetland drying, and within the dry period (default = 365 days)
  • Suitability score = 0 following the dry period and up until the next wetland reconnection event (i.e., stress period; default = 730 days)

An opportunity for fish movement occurs when the following conditions are met:

  • Minimum flow threshold (e.g. 10 000 ML/day)
  • Minimum duration of minimum flow threshold to allow for effective fish movement (e.g. 2 days)
  • Temperature threshold (e.g. 16°C) or seasonal dates that define suitable time of year for fish movement

Assessment methods

This model has no assessment due to the format of its results.


  • Daily flow data
  • Daily temperature data (optional, only required if temperature season is used)
Parameter Sections
  • Flow parameters – define the flow required for a wetland to have water. Includes a cease to flow threshold (or ARI threshold), a stress period, a drying period and if the stress period should be reset after flow
  • Movement parameters – define the flow required for movement. Includes a season, which can be set via dates or days with a temperature above a minimum threshold, along with a flow threshold and a duration.


  • Daily time series of suitability scores (movement events after habitat contraction by no-flow events)

User interface

Underlying code

This plugin is written in Python and its underlying code is publicly available from the Eco Risk Projector computation repository.