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Multi-flow directions in ANUDEM Michael Hutchinson Fenner School of Environmental and Society

Multi-flow directions in ANUDEM Michael Hutchinson Fenner School of Environmental and Society Australian National University. Contents. Background – the 9 Second Australian continental DEM ANUDEM – locally adaptive multigrid method

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Multi-flow directions in ANUDEM Michael Hutchinson Fenner School of Environmental and Society

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  1. Multi-flow directions in ANUDEM Michael Hutchinson Fenner School of Environmental and Society Australian National University

  2. Contents • Background – the 9 Second Australian continental DEM • ANUDEM – locally adaptive multigrid method • Multiple data sources – points, contours, lakes, streams, cliffs • Major anabranches and braided stream networks • Implementation in ANUDEM • Current and future progress

  3. History of Australian DEMs

  4. 9 Second Australian DEM Version 3 2008

  5. Maximum elevation error as functions of cumulative percentage area of the continent

  6. Data Flows for ANUDEM Elevation Gridding Program

  7. Cliff (red) and streamline (blue) data

  8. Automated adjustment of streams and cliffs to represent morphology

  9. Major anabranching systems – Darling River

  10. Major anabranching systems – Murray, Murrumbidgee

  11. Braided Stream Networks

  12. ANUDEM representation of braided stream network

  13. With multi-flow directions

  14. Without multi-flow directions

  15. Very complex braided streams

  16. Two multi-flow grid directions is not enough

  17. Heights not reliable in determining major branches

  18. Conclusions • Up to two flow directions at each stream grid point can represent major anabranching networks • Not always insufficient for complex braided networks • Additional branches required to respect full connectivity of stream data networks – needed for reliable hydrological and catchment analyses – such as revised pfafstedder systems (Janet Stein) • Revised grid flow direction structures needed • Stream heights not reliable in determining principal flow directions • Somewhat distinct from possible representation of multi-flow directions on general hillslopes

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