Fire severity, water repellency characteristics and hydrogeomorphological changes following the Christmas 2001 Sydney forest fires

Richard A. Shakesby, Christopher Chafer, Stefan H. Doerr, William H. Blake, Peter Wallbrink, Geoffrey Humphreys, Ben A. Harrington

    Research output: Contribution to journalArticle

    70 Citations (Scopus)

    Abstract

    Soil water repellency can enhance overland flow and erosion and maybe altered by fire. The Christmas 2001 bushfires near Sydney allowed investigation of the relationship between fire severity, water repellency and hydrogeomorphological changes. For two subcatchments with differences in fire severities in Nattai National Park, south-west of Sydney, this paper considers: (1) the links between fire severity based on SPOT image analysis and ground observation of fire severity and repellency; (2) the textural and organic/minerogenic characteristics of eroded sediment; and (3) erodibility, erosion and deposition of soils in both catchments. Ground surveys show that image analysis reflects well the degree of vegetation consumption by fire, but cannot adequately predict the degree of ground litter consumption, associated soil heating and repellency effects. Fire had varying effects on repellency, leaving it unchanged, destroying it or enhancing it, depending on the soil temperature reached. The main post-fire hydrogeomorphological changes have been widespread erosion and colluvial and alluvial deposition of topsoil in foot-slope locations and river systems, but only localised redistribution of the highly erodible, repellent sandy subsurface layer. The fire did not trigger major geomorphological change in the study area, but fires probably cause important topsoil and nutrient depletion and may also affect water quality.
    Original languageEnglish
    Pages (from-to)147-175
    Number of pages29
    JournalAustralian Geographer
    Volume34
    Issue number2
    DOIs
    Publication statusPublished - 2003

    Keywords

    • Eucalypt
    • Fire severity
    • Forest fire
    • Nattai
    • Satellite image analysis
    • Soil erosion
    • Soil hydrophobicity
    • Soil water repellency

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