Combined impact of the 2003 and 2006/07 bushfires on streamflow: Broadscale assessment

- Report prepared by Sinclair Knight Merz for DSE, July 2009.

The 2003 and 2006/07 bushfires together burned nearly 2.4 million hectares in eastern Victoria and southern NSW, with approximately 130,000 ha being burnt by both fires. These large landscape changes are expected to have a significant impact on streamflows in affected catchments, with increased flows expected immediately after the fires due to the reduction in vegetation cover, and subsequent declines in flows as young regenerating forests establish themselves.

This report details the results of a study undertaken to evaluate the individual and combined impacts of these two recent fires on future streamflows (in the absence of future fires) using the Bushfire Impact on Streamflow Yield (BISY) model. This information helps inform assessments about future surface water availability for the purposes of developing Regional Sustainable Water Strategies.

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• Contents
• Executive Summary
• 1. Introduction
• 2. Study Catchments
• 3. Modelling Framework
• 4. Streamflow Reponse Functions for Regrowth Forests 

• 5. Inputs to BISY
• 6. Assessment of Forest Post-fire Response

• 7. Results - Individual Fire Impacts
• 8. Combined Impact of 2003 & 2006/07 Fires
• 9. Conclusions
• 10. References

• Appendix A: Rules for estimating forest age
• Appendix B: BISY documentation
• Appendix C: Previous post-fire response rules
• Appendix D: Rules for mapping Mixed Eucalypt subcategories
• Appendix E: Catchment results - 2003 fire
• Appendix F: Catchment results - 2006/07 fire
• Appendix G: Catchment results - combined impact for double burnt catchments

• Appendix H: Spatial inputs and outputs - 2003

• Appendix I: Spatial inputs and outputs - 2006/07
• Appendix J: Map figure datasets