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Species specific water requirements

Flow assessment

Generalised and process models

Simultaneous Spell Analysis

About Simultaneous Spell Analysis

Simultaneous Spell analysis allows the identification of simultaneous events in hydrological data where certain criteria are met in many locations at once. These events may need to be identified for many reasons, including:

  • Species specific watering requirements (flow above a threshold for a certain period of time)
  • Checking compliance with water release restrictions
  • Checking for widespread failure with potential for species loss

Model purpose

The purpose of the model is to identify simultaneous events within timeseries data and report a range of summary statistics based on these events. A simultaneous event occurs when all locations in a defined system experience an event at the same time (daily scale). Although commonly used on daily flow data, this model can be used on any timeseries data loaded into Eco Risk Projector. The model reports a range of summary statistics:

  • Count
  • Mean magnitude of peaks
  • Total duration
  • Mean duration
  • Single longest
  • Total duration between spells
  • Mean duration between spells
  • Single longest between spells

For each season present in the data (The season is defined by the input parameters).

The modal also provided a list of all the identified simultaneous events, along with an overall summary of these events containing the following statistics:

  • Threshold
  • Total duration
  • Mean duration
  • Max duration
  • Mean duration between spells
  • Max duration between spells

Development context

This model has been developed based on the expertise of industry experts.

It was developed as a general tool to support the Queensland Department of Environment and Resource Management.

Spatial application

This model is applicable to any location where spells are being assessed simultaneously across locations.

Model description

Ecohydrological rules

This model analyses the data to find events which fit the provided parameters. This means the event must occur within the specified season, meet the specified flow requirements (above, below, range), meet the minimum and maximum length requirements and finally have sufficient independence from all other events. This model then examines these events across all locations, to determine which locations experience simultaneous events. These simultaneous events are then used to calculate the summary statistics.

Assessment method

This model has no assessment, as a spatial component is already built into the results.


  • Daily time series data. This can be any type (flow, depth, rainfall, evaporation, etc.) provided it is at the daily or sub-daily time step.
Parameter Sections
  • Data – define the data type to run analysis on. All time series data types are valid options.
  • Season – define the season to split data into. Specify the start date and end date,
  • Event – define the parameters which determine a spell event. Includes the spell type (above threshold, below threshold, range), the threshold (either a set value or the ARI value), the minimum independence between events, the minimum spell length (optional), the maximum spell length (optional) and the lag (should be specified at each location, to allow the results to be aligned for simultaneous daily analysis).


  • Daily time series of simultaneous spell occurrences
  • Yearly time series of summary statistics for the given season (As defined in the parameters). Based on the daily time series of simultaneous spell occurrences
  • Event list of all simultaneous spell occurrences
  • Summary results for all simultaneous spell occurrences across the analysis period

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.