This overview outlines how bushfires affect streamflow quantity and quality. The effects in the short term (months) are quite different to those in the long term (decades), but both can have significant impacts on the quantity of flow in streams and rivers, the quality of those flows, and the follow-on effects for water supply and the environment.
The fires that occurred in the summers of 2001/02, 2002/03 and 2006/07 in Victoria, NSW and the ACT have coincided with perhaps the largest drought on record. In places, the intensity and extent of these fires have been far more severe than the "Ash Wednesday" fires in 1983, and comparable to the "Black Friday" fires of 1939. Aside from the tragic human and property losses experienced, we can expect, and have observed, major changes in water catchments which affect all water users - human and otherwise.
Physical, chemical and biological processes in natural ecosystems are all disturbed when wildfire consumes a forest. To describe the expected consequences of forest fire, we here outline the kinds of changes that occur, then apply that information to water-related issues.
The diversity of forest types, topography, soils and rainfall patterns across southeast Australia means that catchments can respond to fires in markedly different ways. The impacts of fire described below are necessarily general in nature, but exceptional or extreme responses often occur. Thus, we do not intend to describe either the worst or the best consequences of fire, but we do try to alert the reader to the range of impacts that might be anticipated. The publications listed on this website describe a wealth of observations from historical fires, not only in Australia. As always, application of those experiences to a local catchment should be done with extreme caution and an understanding that other unrecognised factors may determine the response of each catchment.
This site also contains answers to a list of Frequently Asked Questions (FAQs). In most cases, the background to the FAQs is described or mentioned in these Background Sections. Keywords are given for the major topic areas, and these are linked to the publications that are listed on this website. In some cases, key references are also given throughout these background pages.
Please note that the words 'fire', 'bushfire' and 'wildfire' are used interchangeably through these pages.