Areas of catchments that drain directly to Victorian estuaries - i.e. not via major freshwater tributaries.  The layer was derived by Deakin University as part of the project: "Linking catchments to the sea: Understanding how human activities impact on Victorian estuaries" funded by the National Heritage Trust and the Department of Sustainability and Environment.

Areas of catchments that drain directly to Victorian estuaries - i.e. not via major freshwater tributaries.  The layer was derived by Deakin University as part of the project: "Linking catchments to the sea: Understanding how human activities impact on Victorian estuaries" funded by the National Heritage Trust and the Department of Sustainability and Environment.

Areas of catchments that drain to directly to Victorian estuaries (rather than via main tributaries), excluding the Gippsland Lakes basin.  It complements the Fluv_catchments layer that comprises areas of catchments draining to estuaries via fresh water tributaries.  The ESTUARIES layer is an updated version of one that included estuaries and their upstream limits for catchment delineation.  In this layer, attributes relating to population, outcropping geology, land use, geomorphology and rainfall are associated with each catchment polygon. 

In order to assess the relationships between catchment-based activities and estuary condition attributes from this layer were analysed as part of the Deakin University project "Linking catchments to the sea: Understanding how human activities impact on Victorian estuaries".  Methods and results from this project are reported in Barton, J.L., Pope, A.J., Quinn, G.P. and Sherwood, J.E. (2008) Identifying threats to the ecological condition of Victorian estuaries (Department of Sustainability and Environment Technical Report, ISBN 978-1-74208-745-0 (online)).

Polygons were created based on modelling of data from multiple sources as described above.  
The majority of catchment boundaries follow Vicmap 20m DEM cell boundaries.  Metadata for the DEM states that it is suitable for use at a 1:25,000 scale. Where coarser DEMs and watercourse were used, there is less positional accuracy of boundaries.

Attributes for catchment polygons have been derived from a range of sources with differing collection dates and scales.  While valid for broad scale comparisons across multiple systems, the accuracy of attributes may not be suitable for other applications.  Refer to metadata of source layers for further details.

Dataset Source: Data Set Source:
Mean population density estimated from census collection districts (Australian Bureau of Statistics digital boundaries and data) for 2001 and 2006 censuses.  Total catchment population derived from mean density and total area. 

Geological classes were derived from GEOL250 for Victoria and the 'Surface geology of Australia 1:1,000,000 scale, New South Wales' layer from Geosciences Australia

Landuse was derived from several regional layers with currencies between 1997 and 2003:
Gippsland Land Use 1:25000;
Land Use Classification of  North Central CMA;
Land use of South-West Victoria - Port Phillip Region (Zone 55);
Land use of South-West Victoria - Glenelg-Hopkins & Corangamite Region (Zone 54);
Land use of Mid-Goulburn-Broken Catchment;
2003 South Australia State Land Use; and, for areas not covered by the above: 
2001/02 Land Use of Australia, Version 3.

Physical aspects of catchments were derived from Vicmap 20m resolution DEM.

Annual rainfall derived from 0.025 degree grid of Mean Annual rainfall Data (Base Climatological Data Sets) from the Bureau of Meteorology (1961-1990).

Dataset Originality: Primary & Derived

                            
                              History: Data Collection Method: 
Catchment polygons were derived primarily from Vicmap DEM (20m resolution) and 1:25,000 Vicmap Hydro watercourse and water area layers.  Processing and data limitations required the Little and Werribee catchments to be derived from resampled DEM information at 100m resolution and 1:250,000 scale watercourse data (see HYDRO250 metadata).  The South Australian portion of the Glenelg catchment was derived using 9 second resolution data.  The Snowy catchment was derived using a 40m pixel size.

For derived attributes refer to metadata for relevant source below.


Current Design Issues: Polygons showing boundaries of catchments are based on data at a range of scales that were appropriate for their original uses but should be taken into consideration if using the data for other purposes.  Similarly, attributes associated with the polygons were derived from data at a range of scales from sources that were appropriate for the original project but may not be so for other uses.  

Upstream limits of some estuary channels are based on derived locations and estimates.  Such limits are indicative only (refer to ESTUARIES metadata and layer).

Use of this layer is currently limited to display, query and some spatial analysis work since the data does not have a persistent unique identifier. This is due to the likelihood of revision of the set of estuaries in the future.

Future Design Issues: Inclusion of Gippsland Lake tributary estuaries.

Improve estimates of upstream limits of estuaries to 1:25,000, especially W Gippsland.

Changed locations of estuary heads will allow fluvial and estuarine catchment areas to be revised to reflect new boundary positions.

Revise estimates of derived attributes when consistency, currency or resolution of other sources is improved.

Investigate the feasibility of a persistent unique ID is flagged for future development considerations.

Related Documents: None

Refer to metadata for sources and Barton et al. (2008).