What is MFAT?

MFAT is a decision support system that relates river flow to potential habitat condition for river and floodplain environments. MFAT can help governments and communities make informed decisions on environmental flows for the River Murray system.

MFAT:

• uses the best available scientific information
• provides consistent and repeatable assessment
• integrates assessments from river zones to the whole river system
• documents the source and confidence of supporting ecological evidence
• is based on the prototype Environmental Flows Decision Support System (EFDSS) developed by CSIRO Land and Water and Environment Canada

How does MFAT work?

MFAT provides a score of the potential condition of habitat for floodplain and wetland vegetation, waterbirds and native fish for any given flow pattern. Scores range from 0 ('unsuitable') to 1 ('ideal') habitat conditions. MFAT also provides a score of the risk of nuisance blue-green algal blooms.

MFAT uses ecological models to assess habitat condition based on modelled daily river flows. Some ecological models use daily river flow data directly; others use the floodplain hydrology model to generate the required flow data.

The models are driven by ecological information from selected localities (where an assessment is made) along the river. Results for localities are then grouped to provide habitat condition scores for river zones and the whole river system.

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Ecological Models

The MFAT contains five ecological models. The first four models assess potential habitat condition under different flow scenarios for:

• Floodplain vegetation
• Wetland vegetation
• Waterbirds
• Native fish

The fifth model is an assessment of Algal growth.

The ecological models are associated with particular 'locality types' and use river flow data either directly or via a floodplain hydrology model, as described in the table below.

Preference Curves
Preference curves summarise the ecological information that underpins the assessment models. They describe the preferred habitat condition (e.g. flood timing) for selected species.

As an example, the preference curve below describes the months of the year adult vegetation of a particular species prefers to be inundated with floodwater in order to maintain its condition (1 = most preferred, 0 = least preferred).

Click on the 'information' button on the preference curve below for more explanation.

Preference curves are developed for adults as well as recruitment and can be combined to give an overall habitat condition score.

You can view all the preference curves used in MFAT by following the links in the MFAT Results section.

Evidence Fields
The preference curves and other ecological information contained in the MFAT come from sources ranging from expert knowledge and judgment through to published scientific information. Within MFAT the confidence and source of this information is transparently recorded.

MFAT records:

• author
• date of entry
• evidence
• confidence level
• sources

Weights
MFAT uses weights to indicate the relative importance of different components of the ecological models, or of different species/groups or localities within a zone.

Examples from the waterbird model are the relative importance of:

• breeding and foraging habitat to the overall waterbird habitat condition
• flood duration, rate of fall, dry period and nesting vegetation to breeding habitat condition

More information on the weights used in MFAT can be obtained by ordering a read-only version of the MFAT on CD-ROM.

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Daily river flows

Modelled daily river flows presented as 'flow scenarios' are used as input to MFAT.

A flow scenario is a set of daily river flow records for selected river locations modelled over a given period of time (at least 100 years). Flow scenarios provide information about daily flow volumes and include assumptions about how, where and when flows are released and managed in the river system.

Flow scenarios are provided by a river hydrology model. Modelling over a period of time reveals variations that can be expected based on historic weather patterns (e.g. wet and dry years). A 'natural'and 'current' flow conditions scenario are usually included for comparison with other flow management scenarios that are being assessed.

You can find out more information on the flow scenarios assessed using MFAT in MFAT & The Living Murray.

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Floodplain Hydrology Model

For some ecological models (listed in the table above) MFAT uses a floodplain hydrology model.

The floodplain hydrology model uses daily river flows to calculate the volume and timing of water reaching floodplains and wetlands at any given level of river flow.

The floodplain hydrology model represents floodplains and wetlands as a network of storages connected by pipes (in a mathematical sense). A 'floodplain configuration' is like a mud map of an area which defines 'storages' of a certain 'locality type' that are linked to particular ecological assessments.

The storages fill and empty depending on the volume of water they receive and the capacity of the storages and the pipes. The capacity of the pipes defines the rate at which water can be transferred to or from a storage. Factors such as water seepage into the ground and evaporation are also considered.

The diagram below shows an example of how a floodplain configuration set up to model the response of River red gum and Cumbungi rushland would be represented in the floodplain hydrology model.

The two storages are fed by a 'pipe' from the river. The model keeps track of when water moves out of the river and into the floodplain and wetland storages. A 'partitioning storage' separates the water that (theoretically) continues down the river from that moving to the floodplain and wetland storages. To do this, the model needs information on the river flow at which water will leave the river and begin to fill the storage, and the pipe capacity.

The model also requires information on the volume:area relationship of the storages being modelled. The floodplain hydrology model can be calibrated using historical information.

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Results

MFAT combines river flow information with species preferences to calculate an annual habitat condition score (between 0 and 1) for each year of flow record (>100 years).

When plotted, the 'time series' of annual scores varies depending on the suitability of the flow conditions for a particular species/group in any given year.

For 'Inside MFAT', the annual scores are summarised using the arithmetic mean (or 'average') to give a single score for each scenario assessed.

MFAT can also:

• calculate a range of graphical and tabular summary statistics (e.g. mean, median, min, max, S80, coefficient of variation)
• display outputs as time series, cumulative distribution functions or seasonal averages
• provide spell analysis
• compare results for two different scenarios at a time
• integrate assessments spatially (i.e. from localities to zone to system)

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More detailed information

For more technical information please refer to the MFAT Technical Manual [PDF 2.9 MB].

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