| Dataset Number | 1028 |
| Dataset Title | Surface Water Catchments |
| Custodian | Data Authority: Department for Environment and Water
Data Provider: Department for Environment and Water
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Description
| Description | A dataset displaying the boundaries of the surface water catchments of the Mount Lofty Ranges, Mid-North, Southern Flinders Ranges and Kangaroo Island. Attributes include catchment name, area, perimeter, name of coincident basin, drainage type and drainage division. Catchments were taken as areas from which surface runoff flows to the sea, a major waterbody (eg Lake Torrens), or a major river (eg the River Murray). |
| Usage | For planning purposes of catchment based processes and map production. |
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Data Quality
| Lineage | The source data were the contours and drainage spatial layers available in the 1:50,000 scale TOPIS data obtained from the Environmental and Geographic Information Division of the Department for Environment and Heritage circa 1997. The catchment boundaries were digitised on-screen (heads-up digitising) using the contour and drainage layers as the reference for the ground topography. The correct hydrology was determined by considering where a water drop falling on each point of the land would flow. In hilly areas with reasonably dense contour data the correct position of the catchment boundaries could, generally, be determined with little uncertainty. However, in flatter terrain the interpretation of surface hydrology is difficult and the catchment boundaries in these areas should be used with caution. Further details are given under Positional Accuracy. |
| Completeness | All linework has been re-digitised commencing November 2001. Linework will be updated as additional information becomes available (A working group began a review process of this and other catchment related datasets in September 2002). Linework that is likely to change includes catchment boundaries in urban areas and flat areas with poorly defined surface drainage. |
| Positional Accuracy | In general, the spatial accuracy of the catchment boundaries is similar to that of the contour data, i.e. suitable for use at 1:50,000 scale. In hilly areas, the catchment boundaries are generally hydrologically correct at the scale and accuracy of the contour data. However, in flat areas and areas with urban development, there is uncertainty as to the correct location of catchment boundaries as outlined below. Where contour detail permitted (i.e. hilly areas), the catchment boundaries were digitised on-screen at scales around 1:10,000 using a minimum vertex spacing around 25m. The catchment boundaries in these areas are, generally, as hydrologically correct as can be interpreted from the contour data. However, there are some areas (e.g. broad slopes with many small shallow gullies, and broad flat intersecting spurs and hilltops) where the exact surface hydrology can not be determined with certainty without field surveys. These areas are generally small and relatively insignificant at the 1:50,000 scale. In flatter areas with more widely spaced contours, the interpretation of surface hydrology becomes more difficult and is open to operator interpretation. A further aspect to consider in the flatter areas is whether there is actually any surface runoff. In general, a watercourse that crosses a flat plain is a losing stream and the surrounding land does not contribute to runoff as rainfall infiltrates INTO the ground and becomes groundwater. In times of high stream flow, water frequently floods out of the watercourse and onto the surrounding land. In these flat plains the approach to catchment boundary definition was to include a strip of land on each side of the watercourse where the contour data indicated a ridge may be present. If no ridge was indicated, a narrow strip on either side of the watercourse was included (arbitrarily taken as 300-500m wide). |
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Geographic Extent
| Extent Name | South Australia |
| Min Easting or Longitude | 129 |
| Min Northing or Latitude | -38.25 |
| Max Easting or Longitude | 141 |
| Max Northing or Latitude | -26 |
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Dataset Status
| Initially Acquired | 01-NOV-2001 |
| Last Updated | 17-JUN-2003 |
| Update Frequency | Irregular |
| Maintenance Method | As required |
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| AusGOAL | CC BY (Attribution) |
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