Research Library Resource management technical reports Natural resources research 2001 Extent and impacts of dryland salinity Rod Short Cecilia McConnell Follow this and additional works at: https://researchlibrary.agric.wa.gov.au/rmtr Part of the Hydrology Commons, Natural Resources Management and Policy Commons, Soil Science Commons, and the Water Resource Management Commons Recommended Citation Short, R, and McConnell, C. (2001), Extent and impacts of dryland salinity. Department of Primary Industries and Regional Development, Western Australia, Perth. Report 202. This report is brought to you for free and open access by the Natural resources research at Research Library. It has been accepted for inclusion in Resource management technical reports by an authorized administrator of Research Library. For more information, please contact [email protected]. ISSN 0729-3135 January 2001 Extent and Impacts of Dryland Salinity Rod Short and Cecilia McConnell Resource Management Technical Report 202 Western Australian component of Theme 2 prepared for the National Land and Water Resources Audit EXTENT AND IMPACTS OF DRYLAND SALINITY Author details: Rod Short Catchment Hydrology Group Natural Resource Sciences Agriculture Western Australia Pinjarra WA 6208 Cecilia McConnell Catchment Hydrology Group Natural Resource Sciences Agriculture Western Australia South Perth WA 6151 Disclaimer The contents of this report were based on the best available information at the time of publication. It is based in part on various assumptions and predictions. Conditions may change over time and conclusions should be interpreted in the light of the latest information available. Chief Executive Officer, Department of Agriculture Western Australia 2001 2 EXTENT AND IMPACTS OF DRYLAND SALINITY Contents Summary ..................................................................................................................................... ...........5 1.0 Introduction......................................................................................................................................9 2.0 Methodology ..................................................................................................................................10 2.1 Extent.................................................................................................................................10 2.1.1 Spatial units. .......................................................................................................10 2.1.2 Groundwater analysis.........................................................................................10 2.1.3 Risk analysis.......................................................................................................12 2.1.4 Current extent. ....................................................................................................12 2.2 Impact resulting from the risk analysis..........................................................................13 2.2.1 Infrastructure.......................................................................................................13 2.2.2 Water resources. ................................................................................................13 2.2.3 Biodiversity. ........................................................................................................14 2.2.4 Agriculture...........................................................................................................14 3.0 Datasets used by the audit...........................................................................................................15 3.1 Spatial units. .....................................................................................................................15 3.2 Groundwater datasets......................................................................................................15 3.3 Data confidence................................................................................................................17 3.4 Constraints and issues raised from applying chosen methodology..........................19 4.0 Results............................................................................................................................................22 4.1 Extent of shallow groundwater .......................................................................................22 4.1.1 Groundwater depth.............................................................................................22 4.1.2 Groundwater quality............................................................................................22 4.1.3 Groundwater trend..............................................................................................24 4.1.4 Current extent based on wet and waterlogged soils ..........................................24 4.1.5 Risk of shallow watertables ................................................................................24 4.2 Impacts of shallow groundwater. ...................................................................................33 4.2.1 Biophysical impacts ............................................................................................33 4.2.2 Economic impacts...............................................................................................45 5.0 Other datasets ...............................................................................................................................49 6.0 Future groundwater monitoring...................................................................................................50 7.0 Key outcomes................................................................................................................................51 7.1 Extent..................................................................................................................................51 7.2 Impacts and implications.................................................................................................52 8.0 Recommendations. .......................................................................................................................55 9.0 Acknowledgments.........................................................................................................................55 References ............................................................................................................................................56 Compact disk containing maps ..................................................................................Inside back cover Appendices 1. Allocation of land use data and water balance calculations..............................................................58 2. Soil-landscape zone number, name, description and area (ha) .......................................................61 3. Soil-landscape system details...........................................................................................................64 4a. Zone area and allocated risk............................................................................................................70 4b. Percentage of each zone at risk of shallow groundwater. ...............................................................72 5. Risk allocated to systems..................................................................................................................74 3 EXTENT AND IMPACTS OF DRYLAND SALINITY 6. AWRC basins and allocated risk as a percentage of basin area. ................................................... 76 7a. Length of highways and allocated risk. ........................................................................................... 77 7b. Length of primary roads and allocated risk. .................................................................................... 79 7c. Length of secondary roads and allocated risk. ................................................................................ 81 7d. Length of minor roads and allocated risk. ....................................................................................... 83 7e. Length of rail and allocated risk....................................................................................................... 85 8. Towns and allocated risk of shallow groundwater........................................................................... 86 9. Stream length and allocated risk of shallow watertable. ................................................................. 87 10. Resource recovery catchment and allocated risk........................................................................... 88 11. Area of perennial vegetation at risk of shallow watertables. ......................................................... 89 12. Important wetlands and allocated area at risk of shallow groundwater.......................................... 91 13. Allocated risk of shallow watertables for agricultural land (ha)....................................................... 93 14. Indicative estimates of the costs of salinity on and off-farm in Western Australia.......................... 95 List of figures 1. Soil-landscape mapping hierarchy. .................................................................................................. 16 2. Soil-landscape zones for south-western Australia. .......................................................................... 18 3. Groundwater monitoring sites used for the NLWRA . .....................................................................