Fire and Water: Framing Fire and Fuel Management of Water-supply Catchments

摘要

If large quantities of litter are needed to stabilise steep forested water catchments in order to provide high quality water, there are substantial negative implications, for fire-suppression success: fine-fuel loads above 8 t/ha on level ground, and less on steep ground, lead to fires for which suppression is unlikely to be successful under extreme fire-weather conditions. With high fuel loads there is potential for high intensity catchment-wide fires following which water quality is compromised by soil erosion and dam capacity reduced by sedimentation. If quantities of forest litter are kept low so that fire suppression conditions are always favourable, would water quality be compromised because of slope instability? In this paper we provide a general conceptual framework for the management of fuels and fires in steep, forested, water catchments where water quality and quantity are paramount; interesting and challenging theoretical issues arise. We flesh out our framework with data from Canberra's mountain catchments following fires in 1983 and 2003. Water yield and turbidity can be assessed for individual catchments and sub-catchments in the light of rainfall intensity and the fuel loads to be found on different slopes so that intervals between fires prescribed for fire mitigation can be determined, ideally without compromising water quality.