Author(s): K. S. Tan; D. J. M. Flower; D. M. Flowers
Linked Author(s):
Keywords: Rainfall event; Runoff coefficient; Antecedent; Hydrologic similarity; Bushfire; Burn severity
Abstract: The February 2009 Victorian bushfires affected approximately 30% of Melbourne's water supply catchments. Previous experience of bushfires in south-eastern Australia indicates fires can affect catchment water balances, potentially increasing short-term runoff due to reduced vegetation cover and changes in soil conditions, and reducing long-term water yield due to forest regrowth. While changes in post-fire runoff can be investigated using conceptual or physically-based catchment models, these approaches often involve modelling assumptions. uncertainties and intensive data requirements. Consequently, there is a need for rapid assessment methods requiring fewer assumptions using readily-available hydrologic observations. In this paper, an approach for comparing pre-and post-fire runoff coefficients for hydrologically-similar rainfall events (and monthly, seasonal and annual periods) is used to investigate short-and medium-term runoff changes. Results reveal mixed catchment responses, with no clear indication of increased runoff in the initial one and a half year post-2009 bushfires possibly due to the relatively low/moderate burn severity and mortality in the two Melbourne Water catchments investigated.
Year: 2011