Lake Eyre Basin (LEB) Aquatic Ecosystems Mapping and Classification

Abstract

This dataset and its metadata statement were supplied to the Bioregional Assessment Programme by a third party and are presented here as originally supplied.

The Lake Eyre Basin (LEB) is an internally-draining basin that takes up almost one sixth of Australia's land mass in the arid and semi-arid interior. It is unique in being one of the only unregulated dryland river systems in the world and having the most variable flows in the world (Puckridge et al. 1998). The first assessment of the health of LEB rivers found them to be in near-natural condition (LEBSAP 2008). The LEB contains wetlands of national and international importance for supporting Australia's waterbird populations (Reid et al. 2010) and nationally threatened and endemic species are found in the SA LEB (Morton et al. 2010). The ecology is driven by the flow regime and cycles from 'boom' periods following large floods through to 'bust' periods with little to no flow (Bunn et al. 2006).

Description

The aims of the LEBRM aquatic ecosystem mapping and classification (AEMC) project were to provide up-to-date mapping and classification of aquatic ecosystems in the SA LEB.

The specific project objectives were to:

* Improve the spatial mapping of aquatic ecosystems

* Build on the work undertaken for the WAD project (Denny & Berens 2014)

* Align with the Interim Australian National Aquatic Ecosystems (ANAE) classification framework (AETG 2012a)

* Identify where aquatic ecosystems are dependent on groundwater (both subsurface and surface expression).

* Consistency in describing aquatic ecosystems

* Grouping aquatic ecosystems with common attribute values into types.

Applications of the classification of aquatic ecosystems include:

* Linking different types to conceptual and other models of ecosystem function (e.g. Imgraben and McNeil 2013)

* Understanding the drivers of aquatic ecosystems to enable assessments of vulnerability and risk

* Inform identification and description of High Ecological Value Aquatic Ecosystems (AETG 2012b)

* Identification of priority areas for data collection by including confidence rankings and 'unknown' categories for each attribute

* Mapping of specific attributes of aquatic ecosystems (e.g. salinity, persistence)

Purpose

The overarching goal of the LEBRM project was to collate a baseline of scientific knowledge around the hydrology and ecology of aquatic ecosystems in the LEB, thus providing an advanced and up-to-date knowledge platform that can support the detailed modelling, impact and risk analysis needs of LEB bioregional assessments. The LEBRM project background, purpose, approach and links to the bioregional assessment are described in more detail in DEWNR (2014). For more information about LEBRM and other water knowledge projects see DEWNR (2014).

Dataset History

Attribution was firstly undertaken at the whole of study-region scale where national, statewide or regional data (including the WAD) were available. For the priority study catchments and major large lakes, local-scale attribution was undertaken to improve the first level attribution.

Whilst the LEBRM AEMC represents a considerable advancement in mapping and classifying aquatic ecosystems in the study region, particularly the priority catchments, significant knowledge gaps still exist. Over a third of all polygons had insufficient data to enable them to be assigned to the broad types identified for the LEBRM project (see Section 2.3.1) and low confidence values applied to many hydrological attributes for the majority of sites. Within the priority catchments, the mapping of floodplains is considered preliminary. Outside of the priority catchments, the lack of differentiation of floodplains from lacustrine system types limited the automated classification of some other attributes, particularly hydrological connectivity. Further, the LEBRM AEMC focused on classifying the priority western catchments; however there is significantly more information available in reports and project datasets that could be used to classify the aquatic ecosystems of the major eastern catchments, the Georgina-Diamantina and Cooper.

Two related issues that could not be resolved through the LEBRM AEMC were the occurrence of overlapping polygons and multiple polygons representing a single aquatic ecosystem. These issues arise from the different methods employed to map aquatic ecosystems in the data sources accessed by the WAD, the WAD importing multiple datasets for the same features, and the LEBRM AEMC adopting a new source of floodplain mapping which overlapped with some prior floodplain mapping.

Data Capture Method Existing data consolidation ; 'Heads-up' digitising, Remote sensing unsupervised classifications ;

Data Capture Scale 1:50 000 ; 1:100 000 ;

Completeness Complete. The spatial data is subject to amendment as and when more data become available.

Positional Accuracy The accuracy is to the scale of mapping (50 metres at 1:50,000 and 300 metres at 1:100,000 mapping scale). This spatial data is to be used at the regional, subregional and catchment level.

As the LEB project area covered a, extensive area, and as existing data was taken from a variety of existing projects they inevitability have a variety of capture scales and accuracies. Accuracies should be considered relative.

Attribute Accuracy 70%

Consistency ESRI ARC/INFO GIS software was used to do topological consistency checks to detect flaws in the spatial data structure, this check ensured that all classified polygons are closed, nodes are formed at the intersection of lines and that there is only one label in each polygon.

Dataset Citation

"SA Department of Environment, Water and Natural Resources" (2014) Lake Eyre Basin (LEB) Aquatic Ecosystems Mapping and Classification. Bioregional Assessment Source Dataset. Viewed 27 November 2017, http://data.bioregionalassessments.gov.au/dataset/9be10819-0e71-4d8d-aae5-f179012b6906.