Short Virtual Presentation & Digital Poster 10th Australian Stream Management Conference 2021

Post-fire erosion and recovery in Warrumbungle National Park – An outlook (#37)

Esther Qinggaozi Zhu 1 , Anthony Clark 1 , Kim Broadfoot 1 , Jennifer Wurtzel 1 , Scott Wallace 1 , Xihua Yang 2
  1. NSW Department of Primary Industries, MARSFIELD, NSW, Australia
  2. Department of Planning, Industry and Environment, Parramatta, NSW, Australia

In 2013, a catastrophic bushfire ravaged Warrumbungle National Park (WNP) in NSW burning almost 90% of the area. Subsequent storm events carried high levels of ash and particulate carbon into streams, which immediately affected water quality. In this study, post-fire erosion was modelled using the RUSLE across WNP. Rainfall erosivity, was estimated by multi-source data fusion. Erosion rates were modelled from rainfall erosivity, groundcover, soil erodibility and landscape factor. Twelve soil plots were installed to observe soil loss and assess model performance. 

It was found that intensive rainfall events immediately after the bushfire increased erosion and sediment entering streams. A longer time gap between bushfire and significant rainfall event has less erosion risk due to opportunities for groundcover recovery when there are favourable seasonal conditions. Soil loss from a single storm event has up to 25 t ha-1, compared to a long-term average 1.06 t ha-1 yr-1. Despite differences in fire severity from soil plots, modelling and observations show declines in average erosion due to widespread groundcover recovery in 1.5 years. The methodology is generic and thus readily applicable to other areas where data are available. Management outcomes included install erosion control works and monitor key mass movement hazard areas.

Future work will potentially include, post-fire recovery and water quality modelling for the mega-fire in summer 2019-20 in NSW coastal region. The existing sensor network will be essential for monitoring water quality in fire-affected areas by real-time tracking of salinity and nutrients, in conjunction with water sampling and lab analysis.

Download Full Paper