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Land classification for the Clarence-Moreton preliminary assessment extent

Created 22/03/2016

Updated 19/11/2019

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Abstract

The dataset was derived by the Bioregional Assessment Programme. This dataset was derived from multiple datasets. You can find a link to the parent datasets in the Lineage Field in this metadata statement. The History Field in this metadata statement describes how this dataset was derived

Shapefile defining landscape classes across the whole Clarence-Moreton preliminary assessment extent (PAE), as created for the Bioregional Assessments program. This landscape classification was developed to characterise the nature of water dependency among the diverse range of assets, based on key landscape properties related to patterns in geology, geomorphology, hydrology and ecology (both natural and modified ecosystems).

CLM Product 2.3 (Section 2.3.3) provides the methodology used to derive the classification.

Dataset History

Methodology is provided in Product 2.3, Ecosystems chapter, as copied below.

There are many different classification and landscape class methodologies which have been developed to provide consistent and functionally relevant representations of ecosystems (e.g. Australian National Aquatic Ecosystem (ANAE) classification framework). Where appropriate, the approach used to derive the 'Land classification for the Clarence-moreton preliinary assessment extent' built on, and integrated these existing classification systems.

The process of devising and implementing a landscape classification for the Clarence-Moreton PAE predominately involved combining existing classes within data associated with aquatic and groundwater-dependent ecosystems, vegetation and land use mapping. The landscape classification was derived from data layers consisting of polygons (e.g. vegetation, terrestrial/surface GDEs or wetlands), lines (stream network) and points (springs, economic groundwater assets) and produced an output polygon dataset.

  1. Classification of polygon features:

The approach taken was formulated in close collaboration with several experts that had extensive experience with the landscapes of the PAE and had input into developing similar classification systems such as the ANAE classification framework (Aquatic Ecosystems Task Group, 2012). The input datasets and rule sets used for analysis of the polygon layers for this component of the classification are given in Table 1 of Product 2.3, Ecosystems chapter.

Geology is the main landscape-forming driver with four types characterising the bioregion:

* Fractured (volcanic) rock

* Consolidated sedimentary rock

* Unconsolidated sedimentary sediments - alluvium

* Unconsolidated sedimentary sediments - estuarine

The fractured rock is represented by the steep escarpment mainly along the Queensland-NSW border within the bioregion. The consolidated sedimentary rock covers the rest of the bioregion except where it is covered by the alluvium associated with hydrological features and floodplains or the estuarine sediments along the coast. The broad geological classification divides the PAE according to Queensland pre-clearing remnant vegetation mapping (9b7bcebf-8b7f-4fb4-bc91-d39f1bd960cb) with the associated landzone classes and NSW Mitchell landscapes (e64597db-453c-46be-a352-360b775d2852). Both datasets were reclassified by a geologist to conform to the four geological types.

  1. Classification of lines (watercourses)

The approach to classifying watercourses in the PAE broadly focused on whether or not they were streams or rivers. The watercourses were primarily based on the Bureau of Meteorology's Geofabric cartographic mapping of river channels derived from 1:250,000 topographic maps (ed3acf9b-888c-4d53-b376-ecab89781651). The Geofabric is a purpose-built GIS that maps Australian rivers and streams and identifies how stream features are connected hydrologically. Detailed descriptions of the Geofabric can be found in the Geofabric product guide (Bureau of Meteorology 2012). The water regime of the Geofabric watercourses was defined according to their hierarchy - either 'river' (hierarchy 'major') or 'stream' (hierarchy 'minor').

Rivers were further classed as 'tidal river' where upstream tidal limits could be determined from published information.

The Geofabric watercourse mapping is a line dataset. As part of processing to derive the output landscape classes, all Geofabric watercourses were buffered 0.5m (total 1m both sides of the watercourse). This did not adequately represent the true extent of some watercourses - particularly estuaries and wide rivers. Accordingly, watercourses were broadened to reflect real extent, where NVIS4_1 dataset (57c8ee5c-43e5-4e9c-9e41-fd5012536374>) classes were 'sea and estuaries' and 'inland aquatic - freshwater, salt lakes, lagoons' and where these waterbodies were not already captured in the aquatic classes defined in Table 1 f Product 2.3, Ecosystems chapter.

Freshwater rivers were differentiated from freshwater streams according to the available Geofabric data and in part this served to acknowledge hierarchical differences in geomorphological and ecological processes within main channel depositional zones as opposed to smaller tributary systems. These rivers and streams were further differentiated from estuarine watercourses, to reflect major functional differences in hydrological processes and ecological function (Table 2 of Product 2.3, Ecosystems chapter).

  1. Classification of points (springs, waterholes, waterfalls and point-based economic receptors)

In the absence of adequate spatial datasets defining location of springs, waterholes and waterfalls, these were classified based on their occurrence in the Assets register (Table 3 of Product 2.3, Ecosystems chapter).

  1. Landscape classification

Landscape classification allows geographical areas to be delineated into classes that are similar in physical and/or biological and hydrological character. Forty-four landscape classes were defined for the Clarence-Moreton PAE (Table 4 of Product 2.3, Ecosystems chapter). For the water regime classes (other than 'springs and waterholes; waterfalls'), these landscape classes are a function of the four geological and four terrain 'types' defined in Table 1 of Product 2.3, Ecosystems chapter, and resulted in 24 landscape classes. The importance of geology as the main landscape-forming driver is discussed in the geology section (within Product 2.3) and Section 2.3.3.1. Terrain exerts a strong influence on morphology, flow patterns and associated biota. The slope thresholds from the Australian National Aquatic Ecosystems (ANAE) classification framework for the Murray-Darling Basin, based on the Stein Index (Brooks et al., 2014), were used to determine the four terrain types- lowland, low energy upland, high energy upland, and transitional environments.

Hydrological features were classified according to their position in the terrain and whether they were a moving or still body of water as well as their permanency.

Modified landscapes are mostly cleared of natural vegetation and are used for agricultural or other human-intended purposes. These were classified into "dryland agriculture" or "irrigated agriculture" (BRS 2009; DSITIA 2014 ). They were acquired from the latest land use data (BRS 2009; DSITISA 2014). Natural vegetation areas were delineated into major vegetation classes based on structure (especially height and cover), growth form and floristic composition (vascular plant species) in the dominant stratum of each vegetation type (Department of the Environment and Water Resources, 2007). It was also delineated between wet and dry sclerophyll forest. Groundwater-dependent ecosystems (GDEs) are vegetation communities that access groundwater on a permanent or intermittent basis (DSITIA 2015). They occur within the main vegetation classes, where groundwater is close to the surface and accessible. Groundwater-dependency was specifically considered through the spatial intersection of GDEs in the Assets register with the vegetation landscape classes, thus resulting in an associated GDE landscape class for each vegetation landscape class.

Derivation of landscape classes was essentially a process of joining different input datasets to create an output polygon dataset representing all landscape classes. Decisions were made at different points during the process about simplification of data (eg. elimination of small polygons), prioritisation of landscape classes when there was overlap of two or more landscape classes, and improvement of data. How to proceed in these instances was based on an understanding of the quality of the input data (spatial accuracy, spatial resolution, attribute accuracy, currency) combined with an understanding both of the requirements of the output land classification for subsequent receptor analysis and of the CLM PAE landscape. Improvement of data (eg. to code missing areas or re-code existing attributes) relied on the use of supplementary contextual data - maps, satellite imagery, reports or other 'contextual' datasets. Improvement was necessary particularly when defining the polygon water regime classes, where it was found that features and/or attributes within the dataset: 9ff7ab58-2e30-4268-bdf3-bc8aa72aa940 did not adequately cover all relevant aquatic features.

While areal representation across the landscape is 'true' for most landscape classes, the area of landscape classes derived from line and point input datasets (stream, river, tidal river, 'waterfalls', and 'springs and waterholes' landscape classes) does not represent real width of these features in most cases, due to the treatment of these during processing - see section 2.3.3.1 of Product 2.3, Ecosystems chapter, for further details.

Dataset Citation

Bioregional Assessment Programme (2015) Land classification for the Clarence-Moreton preliminary assessment extent. Bioregional Assessment Derived Dataset. Viewed 10 July 2017, http://data.bioregionalassessments.gov.au/dataset/a1d97959-d0f9-4deb-ab9b-af88120efd07.

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Additional Info

Field Value
Title Land classification for the Clarence-Moreton preliminary assessment extent
Language eng
Licence Restricted access. This dataset is not available for public distribution.
Landing Page https://devweb.dga.links.com.au/data/dataset/f80ebddb-e74a-4772-aa42-98194b1b1ae9
Contact Point
Bioregional Assessment Program
bioregionalassessments@environment.gov.au
Reference Period -
Geospatial Coverage POLYGON ((0 0, 0 0, 0 0, 0 0))
Data Portal data.gov.au

Data Source

This dataset was originally found on data.gov.au "Land classification for the Clarence-Moreton preliminary assessment extent". Please visit the source to access the original metadata of the dataset:
https://devweb.dga.links.com.au/data/dataset/a1d97959-d0f9-4deb-ab9b-af88120efd07

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