Rapid Response Monitoring of Wildfire Impact on Partitioning of Infiltration and Runoff: The 2003 Aspen Fire in Sabino Canyon, Arizona

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Nijssen0342831In the Southwest, severe fires can destroy as much as 90% of the vegetation and litter cover. Exposed, burned soils are highly vulnerable to intense monsoon rains, leading to increases in surface runoff, peak flows, and erosion rate. These drastic physical and chemical hydrologic changes negatively impact aquatic habitats and endanger human lives and property. The Aspen Fire in the Coronado National Forest north of Tucson has burned in excess of 40,000 acres and destroyed more than 300 structures. This tragic fire offers a unique opportunity to monitor post- fire soil and water conditions in the well-studied Sabino Creek basin. The effects of fire at this point scale have been studied extensively and generally, local scale investigations have shown that the magnitudes of the hydrologic impacts of fire depend on vegetation, topography, temperature, and fire-intensity. What is lacking is a coordinated study that links point scale I hydrologic changes with basin-integrated runoff and stream flow response. The unique opportunity to combine soil physical measurements of infiltration capacity with integrated watershed geochemistry will improve our ability to unravel the partitioning between runoff and infiltration after a wildf1re. Funding sought under this SGER proposal will be used for intensive Data collection in the period immediately following the burn and for continued monitoring over the next year. SGER is selected as the funding vehicle, because of the urgency to start the research before or as close as possible to the start of the monsoon. The motivating science question is: How is the partitioning of precipitation into infiltration and surface runoff affected by wildfire? We propose an intensive data collection campaign to measure the watershed response to monsoon and winter storm events in the wake of the Aspen Fire. Continued monitoring, to gauge recovery, will take place over the remainder of the year. Soil physical measurements, using a modified air permeameter will be made to determine the extent to which fire-induced changes in soil hydraulic properties lead to changes in infiltration and Runoff generation. Stream flow measurements and analysis of soil and water chemistry will b~ used to investigate the catchments response.