Tully River Subcatchments - Tully catchments from a 30 m digital elevation model

This dataset is the Tully River catchment boundaries created using ArcHydro 1.3, with a stream definition threshold of 5,000 cells. Stream definition was determined from a flow accumulation grid which was generated from a 30 m digital elevation model (S. R. Januchowski, R. L. Pressey, J. VanDerWal and A. Edwards. 2010. Characterizing errors in digital elevation models and estimating the financial costs of accuracy. International Journal of Geographical Information Science. in press.)
Purpose:
This data set has been designed to inform conservation and management planning and decision making exercise related to freshwater ecosystems. The subcatchment have been delineated from a 30 m digital elevation model, and therefore, are suitable for addressing catchment management questions at a regional scale.
History:
This dataset is the Tully River catchment boundaries created using ArcHydro 1.3, with a stream definition threshold of 5,000 cells. The catchment grid delineated using ArcHydro was used to convert grid catchments into a catchment polygon feature class. The adjacent cells in the catchment grid that have the same grid code are combined into a single area, whose boundary is vectorized. The single cell polygons and the "orphan" polygons generated as the artefacts of the vectorization process are dissolved automatically, so that at the end of the process there is just one polygon per catchment. The catchment grid was determined from a flow accumulation grid which was generated from a 30 m digital elevation model (DEM). The DEM used in this process was created using a combination of digital topographic contour lines and point data derived from the SRTM high-resolution digital topographic database (http://www2.jpl.nasa.gov/srtm/). The specifications and accuracy of this model are reported in S. R. Januchowski, R. L. Pressey, J. VanDerWal and A. Edwards. 2010. Characterizing errors in digital elevation models and estimating the financial costs of accuracy. International Journal of Geographical Information Science (in press). The topographic contour data had a 20 m positional accuracy (vertical and horizontal).The DEM had a vertical accuracy of 17.53 m in higher-relief areas and 6.31 in low-relief areas.