Large forest wildfires have enhanced annual river flows in the contiguous United States over the past 30 years, particularly in the Pacific Northwest, Lower Colorado and Texas-Gulf regions according to a study in Nature Communications this week. This finding demonstrates that both changes in climate conditions and fire characteristics impact river flow and should be taken into account in local and regional post-fire management strategies.

Ge Sun and colleagues use high-resolution spatial datasets, watershed characteristics and time series over the past 30 years for wildfires, river flow, climate, topography and land cover across 168 locations in the contiguous United States. They find that post-fire river flow responses vary on a regional scale due to differences in regional climates and precipitation. They show that fire increased annual river flow throughout the west, while prescribed burns in the subtropical southeast had limited impact on river flow.

The authors argue that national post-fire management strategies need to take this regional variability into account in order to respond to increasing wildfire frequency while managing a growing demand for water and water-related services.