More models

Species specific water requirements

Flow assessment

Generalised and process models

Fish barriers and connectivity

About Fish barriers and connectivity

Migration and dispersal are key components of freshwater fish life-history strategies for many fish species that occur in Australian rivers. The presence of natural and artificial barriers in a stream can reduce longitudinal connectivity by impeding the passage of fish under certain flow conditions. The purpose of this model is to predict the frequency and duration of fish passage opportunities past barriers under natural and managed stream flow scenarios.

Water requirements

This model has been designed for capturing the criteria for successful transition of instream barriers to allow fish movement. The model allows any number of instream barriers and considers the transition time between those barriers to allow for successful upstream and downstream migration.

Model purpose

The purpose of the model is to assess the long term population viability of fish that are dependent on longitudinal connectivity (both and up and downstream movement) for successful spawning.

Development context

Developed using quantitative life-history information from the literature and expert opinion (see Cockayne et al 2010), this model can be used to quantify the threats to the maintenance of fish communities through failures of longitudinal connectivity.

Spatial application

This model may be applied to any stream system where longitudinal connectivity is important for maintaining healthy fish populations.

Model description

Ecohydrological rules

The model considers the requirements for fish passage of a structure (drownout depth) for both upstream and downstream movement. The model further considers the transit time along reaches between barriers to consider the success of overall system transit across several barriers and the reaches in between those barriers.

Assessment method

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


  • Daily flow data (required for each barrier)
Parameter Sections
  • Global parameters – parameters applied across all barriers in the simulation. Includes swim speed (m/sec.), upstream start AMTD, downstream end AMTD, downstream season and upstream season.
  • Barrier (site) parameters – parameters applied for each barrier. Includes:
    • The barriers AMTD threshold (location in the system)
    • Slope, width and roughness,
    • Drownout threshold for both upstream and downstream navigation of the barrier. A barrier may have different drownout threshold depending on; the species of fish being modelled, the swimming abilities of the size class of fish, and the direction of travel being modelled, i.e. upstream or downstream.
    • Drownout duration for both upstream and downstream navigation of the barrier. Minimum duration required for fish passage (days). Duration times should be species and direction specific and could be age/size class specific


  • Daily time series of successful upstream and downstream movement. Includes intermediate results such as in season and impassable barrier (for both downstream and upstream).

User interface

Underlying code

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


Cockayne B, McGregor G, Marshall J, Lobegeiger J, and Menke N 2010, ‘Fitzroy Water Resource Plan review technical report 3: ecological risk assessment’, Department of Environment and Resource Management, Queensland Government, Brisbane.