Wildfires increasingly impact western US fluvial networks.

Area of Science:

• Environmental Science
• Hydrology
• Ecology

Background:

• Global wildfire frequency, severity, and extent are increasing.
• The impact of wildfires on fluvial networks and water resources is not well understood.
• Existing data on wildfire-induced aquatic impairment is limited.

Purpose of the Study:

• To quantify the stream and river length impacted by wildfire in the western US.
• To estimate the direct and indirect (water quality propagation) effects of wildfires on aquatic ecosystems.
• To highlight wildfire as a significant driver of aquatic impairment.

Main Methods:

• Utilized remote sensing for burn perimeter and severity mapping.
• Employed in-situ water quality monitoring.
• Developed longitudinal modeling to assess impact propagation.

Main Results:

• Wildfires directly impacted approximately 6% of western US stream and river length from 1984-2014.
• The directly impacted length is increasing by 342 km/year.
• Including water quality impacts, wildfires affect an estimated 11% of total stream and river length.

Conclusions:

• Wildfire activity is a major, underreported driver of aquatic impairment.
• Current regulatory reporting does not adequately constrain wildfire impacts on fluvial networks.
• Further research and monitoring are crucial to address the growing threat to water security and public health.