Wildland fire and climate variability impacts on annual streamflow in watersheds across the continental United States: Regional patterns and attribution analysis

The magnitude of wildland fire impacts on water resources varies regionally depending on fire severity, topography, vegetation and climate. An assessment of the potential threat that wildland fire poses to water supplies across the conterminous United States (CONUS) is critically important because forests supply 50% of consumed water. In our assessment, we first performed a double mass analysis of streamflow (GAGES-II) vs. precipitation (PRISM) data from 170 burned watersheds to identify changes in average water yield in the first five years following wildland fire (MTBS burn severity dataset), which were positive in 52 watersheds (Chow test p< 0.1), negative in 69 (p< 0.1), and not significant in 49 (p> 0.1). Subsequently, we separated the respective contributions of fire and climate variability to changes in annual runoff (dQ) by fitting linear climate elasticity models (CEMs), yielding acceptable CEMs (coefficient p …