Stream Salinity Status and Trends in South West
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Salinity and Land Use Impacts SLUI 38 2005 Stream salinity status and trends in south-west Western Australia Salinity and Land Use Impacts Series Stream salinity status and trends in south-west Western Australia SLUI 38 STREAM SALINITY STATUS AND TRENDS IN SOUTH-WEST WESTERN AUSTRALIA by Xanthe Mayer, John Ruprecht and Mohammed Bari Natural Resource Management and Salinity Division Department of Environment DEPARTMENT OF ENVIRONMENT SALINITY AND LAND USE IMPACTS SERIES REPORT No. SLUI 38 JANUARY 2005 i Stream salinity status and trends in south-west Western Australia SLUI 38 Salinity and Land Use Impacts Series Acknowledgments We are grateful to the hydrographic staff of the Department of Environment who have collected and processed accurate streamfl ow and water quality data in a highly professional manner for many years. In particular, we thank Richard Pickett, Andrew Maughan, Kevin Firth, Paul Earp, Kim Griffi n and their teams. We thank Peter Muirden for his extensive contribution to this report. We would also like to thank those who helped to review the document including Dr Richard George, Dr Tom Hatton, Dr Richard Silberstein, Richard Pickett, Andrew Maughan, Kim Griffi n and Martin Revell. Other people who assisted by providing comments and technical advice above and beyond their duties include Sally Bowman, Phillip Commander and Peta Kelsey. The work of the late Dr Luke Pen has been extensively used in this report and the work is gratefully acknowledged. Finally our thanks go to Tim Sparks for guiding the project through its many stages, Alex Waterhouse for technical editing, Mary-ann Berti and Lucie Penman for preparing fi gures and Peter Van De Wyngaard for preparing the maps. For more information contact: Mary-ann Berti Salinity and Land Use Impacts Branch, Natural Resource Management and Salinity Division 3 Plain Street East Perth WA 6004 Telephone (08) 9278 0300 Facsimile (08) 9278 0586 Recommended Reference The recommended reference for this publication is: Mayer, XM, Ruprecht, JK & Bari, MA 2005, Stream salinity status and trends in south-west Western Australia, Department of Environment, Salinity and Land Use Impacts Series, Report No. SLUI 38. We welcome your feedback A publication feedback form can be found at the back of this publication. ISBN 1 920947 25 6 (print) ISBN 1 920947 26 4 (PDF) ISSN 1447-7394 (print) ISSN 1449-5252 (PDF) January 2005 Cover photograph: Rivers, catchment, and associated salinity problems around the south-west of Western Australia L. Pen, J. Alford and T. Sparks. Designed by G. Kernick ii Salinity and Land Use Impacts Series Stream salinity status and trends in south-west Western Australia SLUI 38 Contents Summary ...................................................................................................................1 1 Introduction ............................................................................................................4 1.1 Background ............................................................................................................................ 4 1.2 Objectives ............................................................................................................................... 5 1.3 A brief history of agriculture in the Wheatbelt .........................................................................5 1.4 A brief history of stream salinity .............................................................................................. 6 1.5 The process of stream salinisation .........................................................................................7 1.6 Factors infl uencing stream salinity ......................................................................................... 9 1.7 Chemical composition of river water .................................................................................... 11 2 Methodology ........................................................................................................12 3 Regional salinity status ........................................................................................14 3.1 Introduction ........................................................................................................................... 14 3.2 South Coast Study Area ....................................................................................................... 14 3.2.1 Esperance Coast Basin (601) ........................................................................................................16 3.2.2 Albany Coast Basin (602) ..............................................................................................................18 3.2.3 Denmark River Basin (603) ............................................................................................................20 3.2.4 Kent River Basin (604) ...................................................................................................................23 3.2.5 Frankland River Basin (605) ..........................................................................................................25 3.3 South West Study Area ........................................................................................................ 27 3.3.1 Shannon River Basin (606) ............................................................................................................29 3.3.2 Warren River Basin (607) ...............................................................................................................30 3.3.3 Donnelly River Basin (608) ............................................................................................................33 3.3.4 Blackwood River Basin (609) .........................................................................................................35 3.3.5 Busselton Coast Basin (610) ..........................................................................................................38 3.3.6 Preston River Basin (611) ..............................................................................................................39 3.3.7 Collie River Basin (612) .................................................................................................................41 3.3.8 Harvey River Basin (613) ...............................................................................................................44 3.3.9 Murray River Basin (614) ...............................................................................................................45 3.4 Swan–Avon Study Area (615, 616) ......................................................................................... 47 3.5 Northern Agricultural Study Area .......................................................................................... 56 3.5.1 Moore–Hill Rivers Basin (617) .......................................................................................................56 3.5.2 Yarra Yarra Basin (618) and Ninghan Basin (619) .........................................................................60 3.5.3 Greenough River Basin (701) ........................................................................................................60 3.5.4 Murchison River Basin (702) ..........................................................................................................62 4 Overview of salinity in the south-west ................................................................64 4.1 Patterns of salinity ................................................................................................................ 64 iii Stream salinity status and trends in south-west Western Australia SLUI 38 Salinity and Land Use Impacts Series 4.2 Changes in salinity ............................................................................................................... 67 4.3 Major rivers ........................................................................................................................... 69 4.4 Forested catchments ............................................................................................................ 69 4.5 Water Resource Recovery Catchments ............................................................................... 71 4.6 Groundwater salinity ............................................................................................................. 72 4.7 Salinity relationships ............................................................................................................. 72 4.8 Salt balance .......................................................................................................................... 75 4.9 Salinity and biodiversity ........................................................................................................ 77 4.10 Longer term prognosis ......................................................................................................... 77 5 Conclusions .........................................................................................................78 5.1 Salinity status ....................................................................................................................... 78 5.2 Salinity trends ....................................................................................................................... 78 5.3 Salt balance .......................................................................................................................... 78 5.4 Forested catchments, major rivers and Water Resource Recovery Catchments .................79