Nationally framed assessment and planning as- sists coordination of resource management activities across jurisdictional boundaries and provides context for assess-ing the cumulative effects of impacts that can be underesti-mated by local or regional studies. However, there have been signi?cant shortcomings in the existing spatial frameworks supporting national assessment and planning for Australia’s rivers and streams. We describe the development of a new national stream and nested catchment framework for Australia that includes a fully connected and directed stream network and a nested catchment hierarchy derived using a modi?ed Pfafstetter scheme. The directed stream network with associated catch-ment boundaries and Pfafstetter coding respect all distribu-tary junctions and topographically driven surface ?ow path-ways, including those in the areas of low relief and inter-nal drainage that make up over half of the Australian con-tinent. The Pfafstetter coding facilitates multi-scale analy-ses and easy tracing and query of upstream/downstream at-tributes and tributary/main stem relationships. Accompany-ing the spatial layers are 13 lookup tables containing nearly 400 attributes describing the natural and anthropogenic en-vironment of each of the 1.4 M stream segments at multiple spatial scales (segment, sub-catchment and catchment). The database supplies key spatial layers to support na-tional water information and accounting needs and assists a wide range of research, planning and assessment tasks at re-gional and continental scales. These include the delineation of reporting units for the Australian Water Resources Assess-ment, the development of an ecohydrological environment classi?cation for Australian streams and the identi?cation of high conservation value aquatic ecosystems for northern Australia.
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