Revised Mapping of River Basins the Currently Defined Australian Drainage Divisions and River Basins Were Reviewed As Part of This Inventory of Arid NT Wetlands

12 9 E 13 8 E 20 S 20 S

WISO BASIN BARKLY BASIN

GEORGINA RIVER BASIN

MACKAY BASIN BURT BASIN

FINKE RIVER BASIN

HAY RIVER TODD RIVER BASIN BASIN

WARBURTON BASIN 26 S 26 S 13 8 E 12 9 E roads Lake Eyre Drainage Di vi sion rivers Western Plateau Drainage Divi sion lakes

Figure 9. Map of nationally defined drainage divisions and basins, with major rivers. Drainage divisions and river basins refined as defined by the Australian Water Resources Commission (Environment Australia 2001).

Revised Mapping of River Basins The currently defined Australian Drainage Divisions and River Basins were reviewed as part of this inventory of arid NT wetlands. The review was undertaken as a result of observations and information that indicated inaccuracies in a number of the nationally defined river basin boundaries. The distribution of catchments is important for understanding and reporting the nature and distribution of wetlands in the study area. The method used to refine the basin boundaries is presented below followed by a discussion of the results.

Method

The method was based on terrain analysis using a digital elevation model (DEM) in a geographic information system (GIS). The watershed tool within TNTMIPS V5.9 software was used with the AUSLIG Geodata 9 second DEM (version 2). The DEM cell size of 9 seconds corresponds to roughly 280 x 280 metre. Four levels of watersheds (with pourpoints) were defined by progressive basin fill and then digitally overlain on the existing Australian River Basin coverage. In areas where the DEM generated basin boundaries were substantially different from the nationally defined boundaries, manual checking was conducted. This used the 1:250,000 mapping of drainage, knowledge gained from field observations, previous catchment studies, information from Landsat images during periods of flooding, and more detailed topographic and radiometric data from the Northern Territory Geological Service (NTGS). The radiometric data were used to define the spatial distribution of paleo-floodouts by interpreting alluvial sediment distribution.

Wetlands of the Arid NT Volume 1: 36