Geofabric Surface Catchments - V2.1

## **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 Geofabric Surface Catchments product is derived from the National Catchment Boundaries (NCB) V1.1.4. This data defines a catchment for every stream segment contained within the Geofabric Surface Network product according to the GEODATA Nine Second Digital Elevation Model (DEM-9S) Version 3. These stream segment level boundaries may be used individually or in aggregation. The product is designed to represent geographic surface boundaries that have a hydrological relationship to surface water features. The NCB Level 1 and NCB Level 2 features are the top two levels in the NCB Catchment hierarchy and have been provided as polygon boundaries. This product contains one Geofabric feature type called Catchment. It also contains three NCB feature types including: NCBLevel1Drainage Division, NCBLevel2Drainage Basin and NCBPfafstetter.



(http://www.bom.gov.au/water/geofabric/download.shtml )

## **Purpose** 

This product is intended to support the creation of or definition of topologically consistent and hydrologically enforced streamflow aggregation boundaries.  The catchment attributes can be extending by linking the NCB Pfafstetter table to include the Pfafstetter reference system for identifying and aggregating catchments.



This product is intended to supplement the Geofabric Surface Cartography and Geofabric Surface Network data products. This product is also used to as the basis for building contracted catchments in the Geofabric Hydrology Reporting Catchments product and provides a spatial framework for analysis and assessment of streams and their catchments.

## **Dataset History** 

Geofabric Surface Catchments is part of a suite of Geofabric products produced by the Australian Bureau of Meteorology. The geometry of this product is largely derived from the National Catchment Boundaries (NCB) V1.1.4. It consists of catchments, NCB Level 1 Drainage Divisions, NCB Level 2 Drainage Basins and the NCB Pfafstetter table.  The feature class terminology for Geofabric Surface Catchment components has been modified to distinguish it in terms of the products underlying data model.



The AHGFCatchments are based upon polygons converted from a regular 9 second grid delineating the NCBs for the Australian continent.  The NCBs delineate hierarchically-nested catchments derived using an automated drainage analysis procedure based on a multi-flow extension of the version 3.1 flow direction grid associated with the 9 second DEM (GEODATA National 9 Second Digital Elevation Model (DEM-9S) Version 3, ANZLIC unique identifier: ANZCW0703011541).



At the highest levels in the hierarchy the NCBs aggregate the 9 second drainage basins (9 second Basins product name and ANZLIC identifier to be inserted) into 12 topographically-defined Drainage Divisions (Level 1) and 191 Drainage Basins (Level 2) approximating the Australian Water Resources Council (AWRC) River Basins (Australia's River Basins, Geoscience Australia, 1997 ANZLIC identifier: ANZCW0703005427) where possible.  At lower levels, the Level 2 units are sub-divided into successively finer sub-catchments using a modified version of the Pfafstetter procedure (Verdin, K. L. and Verdin, J. P. (1999) A topological system for delineation and codification of the Earth's river basins. Journal of Hydrology, 218(1-2), 1-12).



This layer delineates the lowest level catchment units being the sub-catchments draining directly to a stream segment in the ANUDEM stream layer or, where there are no ANUDEM Derived Streams (ANUDEM Streams), the 9 second drainage basin. The higher level catchment membership of each of these sub-catchments is derived from its NCB code.

Processing steps: 



1. ANUDEM v1.1.4 National Catchment Boundaries (NCBs) dataset is received and loaded into the Geofabric development GIS environment. 

2. feature classes from ANUDEM NCBs are recomposed into composited Geofabric Framework Dataset feature classes in the Geofabric Maintenance Geodatabase.

3. re-composited feature classes in the Geofabric Maintenance Geodatabase Feature Dataset are assigned unique Hydro-IDs using ESRI ArcHydro for Surface Water (ArcHydro: 1.4.0.180 and ApFramework: 3.1.0.84)

4. feature classes from the Geofabric Maintenance Geodatabase Feature Dataset are extracted and reassigned to the Geofabric Surface Catchment Feature Dataset within the Geofabric Surface Catchment Geodatabase.



A complete set of data mappings, from input source data to Geofabric Products, is included in the Geofabric Product Guide, Appendices.

## **Dataset Citation** 

Bureau of Meteorology (2011) Geofabric Surface Catchments - V2.1. Bioregional Assessment Source Dataset. Viewed 12 December 2018, http://data.bioregionalassessments.gov.au/dataset/ea1b6f6c-e8a3-4c78-a463-044c89857fc0.

Tags: Australia, Cooper subregion, Galilee subregion, Gloucester subregion, Hunter subregion, inlandWaters
Organization: Bioregional Assessment Program