Estimating impacts of bushfire and climate variability on streamflow in
Victoria, Australia
Abstract
Bushfires are common in Australia and can cause vegetation loss and
affect hydrological processes such as interception, evapotranspiration,
soil water storage and streamflow. This study investigates bushfire
impacts on catchment mean annual streamflow for 14 Australian catchments
that have been severely impacted by the 2009 Victoria bushfire, the
second worst bushfire disaster in Australia. A statistical approach
based on sensitivity coefficients was used for quantifying the climate
variability impacts on streamflow and the time-trend analysis method was
used to estimate the annual streamflow changes due to bushfire
respectively. Our results show that bushfire has caused a noticeable
increase in mean annual streamflow in majority of burnt catchments for
an immediate post bushfire period (2009-2015), when the bushfire impact
on streamflow is evidently larger than the climate change impact.
Furthermore, the bushfire impact on mean annual streamflow linearly
increases with the burnt percentage area. These results provide strong
evidence for evaluating large-scale bushfire impact on streamflow at
small to medium sized catchments, and guidance for process-based
hydrological models for simulating bushfire impacts on hydrological
processes for the immediate period after bushfire.