Over the last three decades, California has seen increasing erosion after major wildfires — a phenomenon that not only endangers water resources and ecosystems, but is also likely to worsen with climate change, according to researchers.

A new study from the U.S. Geological Survey documented a tenfold increase in post-fire hillside erosion in Northern California from the late 1980s to the 2010s, with the majority of the largest sediment-producing fires occurring in the last decade.

This erosion causes a number of problems. When heavy rains scour charred hillsides, debris flows can choke rivers and streams, depriving fish of oxygen. Sediment runoff can also fill reservoirs and take up valuable water storage space, damage flood control infrastructure and threaten nearby communities vulnerable to flash flooding.

The research team noted that erosion after wildfires has accelerated across the state since 1984, with the northern half of the state recording the most noticeable change.

"In Northern California, we really see this huge increase [in post-fire erosion] from the first decade to the second to the third to the fourth," said Helen Dow, a research geologist with USGS and the study's lead author. "There's just a large rise in sediment, both in mass ... and then also when we look at yield, being the mass per area."
This story originally appeared in the Los Angeles Times.

Story Date: September 11, 2024