Disaggregation of the Central Mallee and Hopetoun Land Systems Using the Digital Elevation Model
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Disaggregation of the Central Mallee and Hopetoun Land Systems using the Digital Elevation Model April 2009 Publication details Acknowledgements Dissaggregation of the Central Mallee and The Mallee CMA and the DPI project team Hopetoun Land Systems using the Digital would like to thank retired soil scientists Jim Elevation Model Rowan and John Martin for furnishing us with their immense knowledge of the geo- Mallee Catchment ISBN No: 978-1-74217-450-1 (print) morphology and soils of the Mallee area. Management Authority ISBN No: 978-1-74217-451-8 (online) We would also like to acknowledge the www.malleecma.vic.gov.au participation and involvement of DPI PO Box 5017 Mildura 3502 April 2009 colleagues across North–West Victoria in Telephone 03 5051 4377 Sponsor: Australian Government’s National field validating and sharing their knowledge Facsimile 03 5051 4379 Action Plan for Salinity and Water Quality on the region. Victorian Government Department of Copyright Primary Industries. The Department of Primary Industries was © Mallee Catchment Management engaged by the Mallee Catchment Authority 2008 and The State of Victoria, Authors: Jonathan Hopley, Nathan Management Authority (CMA) to undertake 2009 Robinson, Richard MacEwan and David this project with funding provided by the Rees Australian Government’s National Action This publication is copyright. No part Department of Primary Industries Plan for Salinity and Water Quality (NAP) may be reproduced by any process Future Farming Systems Research and the Victorian Government Department except in accordance with the provisions Bendigo of Primary Industries. of the Copyright Act 1968. Cover images Disclaimer Left: East–west dunes of the Central Mallee Publications produced by the Mallee Land System. Catchment Management Authority and Middle: Jim Rowan and John Martin with the State Government of Victoria may be DPI Staff of assistance to you but the Mallee Right: Elongated ridge in the distance Catchment Management Authority and located east of Speed. the State Government of Victoria and its Cover photos: DPI employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purpose and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this or any Mallee Catchment Management Authority publication. Project partners DEPARTMENT OF PRIMARY INDUSTRIES Contents Acknowledgments.................................................................................................................... iv Summary................................................................................................................................... v 1 Introduction........................................................................................................................ 1 1.1 Aims and objectives................................................................................................................. 2 1.2 The study area.......................................................................................................................... 2 2 Methodology ....................................................................................................................... 5 2.1 Terrain analysis using rulesets on derived surfaces ............................................................. 6 2.2 Terrain analysis using MrVBF and FLAG ........................................................................... 6 2.3 Combining the ruleset map model and the FLAG/MrVBF model outputs........................ 9 2.4 Cleaning the dataset/removing noise from the dataset....................................................... 10 2.5 Validation of model outputs.................................................................................................. 10 3 Results and discussion ..................................................................................................... 12 3.1 Disaggregation of land systems ............................................................................................ 12 3.2 Descriptions of landform components ................................................................................. 16 3.3 Land system disaggregation accuracy assessment.............................................................. 27 3.4 Landform pattern regions..................................................................................................... 28 3.5 Area analysis and statistics of the landform components .................................................. 29 4 Conclusion ........................................................................................................................ 32 4.1 Recommendations.................................................................................................................. 32 References ............................................................................................................................... 34 Appendix 1 Field validation route map............................................................................... 35 Figures Figure 1 The Central Mallee and Hopetoun land systems highlighted from Rowan and Downes (1963) mapping.................................................................................................................................................................2 Figure 2 Central Mallee land system terrain section (from Rowan and Downes 1963) ......................................3 Figure 3 Hopetoun land system terrain section (from Rowan and Downes 1963) ..............................................4 Figure 4 A chart summarising the land disaggregation methodology..................................................................6 Figure 5 Mosaic of images showing various surface layers derived from the central DEM elevation dataset. The same view, presented in each image, is of a linear east–west dune in the Central Mallee Land System ....................................................................................................................................................................7 Figure 6 Sectors of the Central Mallee and Hopetoun land systems where the MrVBF and FLAG models were trialled...........................................................................................................................................................7 Figure 7 UPNESS index cdf log plot with three points discriminating four landform elements (source: Summerell et al. 2005). .........................................................................................................................................9 i DISAGGREGATION OF MALLEE LAND SYSTEMS Figure 8 A section of the Central Mallee Land System showing east–west dunes before cleaning (left) and after cleaning (right). Notice how the missing cells of the crests have been filled and the small areas previously assigned as dunes have been removed ........................................................................................10 Figure 9 Sectors of analysis for ridge and lakebed landform components. Each sector has a slightly different elevation threshold applied by the ruleset......................................................................................................12 Figure 10 Example area of the Hopetoun Land System mapping with the disaggregated landform components. All landform components are represented in this map .........................................................14 Figure 11 East–west dunes in the Central Mallee Land System. The left image shows the classified dunes (yellow border) superimposed over the relative elevation (70 m) surface, the right image shows the same dunes superimposed over the aerial photography. The north–south extents of the dunes seem to match well with the imagery; however the areas identified in the red boxes show an under‐ classification in this area....................................................................................................................................15 Figure 12 Extent of the classified ridges in a part of the Hopetoun Land System superimposed over a hill‐ shading of the DEM. The red box on the left highlights ridge areas that have not been classified as ridges whilst the box on the right shows a large lunette that was later classified as ‘lunettes associated with ridge’. ..........................................................................................................................................................15 Figure 13 East–west dunes of the Central Mallee Land System...........................................................................17 Figure 14 East–west dunes on the western slopes of a ridge................................................................................18 Figure 15 Elongated ridge in the distance located east of Speed..........................................................................19 Figure 16 Gentle rise located on an elongated ridge..............................................................................................20 Figure 17 Lower ridge slopes located east of Speed...............................................................................................21 Figure 18 Gentle rise on an undulating plain east of Ouyen ................................................................................22 Figure 19 Interdune swale (corridor) near Manangatang .....................................................................................23