A MULTI-MODEL APPROACH TO PROJECT REGIONAL POST-FIRE SEDIMENT DYNAMICS

Wildfire dramatically affects landscape response to rainfall by altering hydrologic and sediment delivery processes within burn sites and delivering sediment pulses to streams and rivers that propagate far downstream. Assessing the potential resiliency of watersheds to future hazards associated with wildfire therefore requires analysis of complex interactions among burn severity, soil and parent material characteristics, topography, climate, and streamflow. With an expected increase in the frequency and severity of wildfires in the western United States as a function of climate change, we must link wildfire-induced increases in runoff and erosion to downstream erosion and sedimentation process in order to understand watershed resiliency and mitigate potential hazards associated with changing wildfire and precipitation regimes. In this presentation, we describe a data synthesis framework for improving holistic projections of future post-fire sediment dynamics for the western United States by integrating existing spatially-explicit projections of fire, hillslope sediment delivery to streams, and streamflow to forecast sediment transport along a continuum from hillslopes to channels through the year 2050. Most research on post-fire sediment dynamics is limited in spatiotemporal scope. This synthesis framework allows us to predict areas that may face costly sedimentation and water quality issues as a result of wildfire at decadal scales across many important watersheds of the western U.S., where wildfire-prone areas are located in close proximity to large and growing population centers. Natural variability in watershed responses to increased fire, coupled with forward-looking watershed management, may lead to differential watershed resiliency to climate change that can be leveraged for societal benefits.