The effect of wildfire on runoff and erosion in native Eucalyptus forest

✍ Scribed by Ian P. Prosser; Lisa Williams

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 212 KB
• Volume: 12
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/(sici)1099-1085(199802)12:2<251::aid-hyp574>3.0.co;2-4

✦ Synopsis

Wild®res raise concerns over the risk of accelerated erosion as a result of increased overland ¯ow and decreased protection of the soil by litter and ground vegetation cover. We investigated these issues following the 1994 ®res that burnt large areas of native Eucalyptus forest surrounding Sydney, Australia. A review of previous studies identi®es the ®re and rainfall conditions that are likely to lead to increased runo and accelerated erosion. We then compare runo and erosion between burnt and unburnt sites for 10 months after the 1994 ®res.

At the scale of hillslope plots, the 1994 ®re increased runo by enhancing soil hydrophobicity, and greatly increased sediment transport, mainly through the reduced ground cover, which lowered substantially the threshold for initial sediment movement. However, both runo and sediment transport were very localized, resulting in little runo or sediment yield after the ®re at the hillslope catchment scale. We identify that after moderately intense ®res, rainfall events of greater than one year recurrence interval are required to generate substantial runo and sediment yield. Such events did not occur during the monitoring period. Past work shows that mild burns have little eect on erosion, and it is only after the most extreme ®res that erosion is produced from small, frequent storms.