Van Tuyl Lecture, April 21, 2025, Berthoud 205, 12-1pm

Ben Livneh, University of Colorado, Boulder

Burning Questions: Unraveling Wildfie Ripples from Water Quality to Landslides

Abstract: Wildfires fundamentally alter the dynamics of both water quality and landscape stability, presenting a cascade of challenges across multiple scales. This presentation synthesizes recent research investigating two interrelated consequences of wildfires. First, through a combination of laboratory simulations and field analyses, we examine wildfire-induced increases in sediment, nutrients, dissolved organic matter (DOM), and altered runoff patterns. Small-scale experiments with 154 soil samples reveal that higher burn intensities significantly enhance runoff and sedimentation, while alternating changes in DOM and nitrogen levels underscore the complexity of post-fire chemical responses. A complementary watershed-scale analyses across 241 western U.S. basins further demonstrates that water quality constituents, such as sediment and turbidity, can remain elevated for up to six years following a fire, highlighting persistent challenges and knowledge gaps in predictive modeling.

Second, we evaluate the impact of wildfire on the triggering mechanisms of rainfall-driven landslide hazards. Accumulated precipitation preceding over 5000 mass movement events from six global regions was analyzed, indicating that burned sites require less rainfall to initiate landslides compared to unburned areas. Additionally, a detailed examination of event seasonality revealed that in regions like the Pacific Northwest, storm timing for mass movements in burned areas diverges from typical rainfall-triggered events, although data limitations in areas such as the Himalayas add uncertainty to these findings. By integrating insights from both water quality and mass movement hazards, this research seeks to advance our understanding of the complex interplay between wildfire impacts and subsequent environmental risks, identifying areas for improved management strategies and predictive capabilities.