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Scientists say it’s a megafire that has caused more than a century of erosion near Lake Utah, but there’s more to it.

BYU students take water samples from the river in Spanish Fork Canyon. Credit: BYU Photo

Two BYU students found valuable research opportunities when Hurricane Rosa stormed Baja California in October 2018.


Utah County, still smoldering with the devastating Paul Creek megafire that same year, was predicted to have a heavy rainy day triggered by a hurricane landing.For months, Trevor Crandal and Erin Jones were collecting Water sample Understand how land use and wildfires affect the health of streams and lakes on a tributary of Lake Utah. Now they had the rare opportunity to observe how a series of extreme events affected water quality and quantity.

“Erin and Trevor have brought together a team of our undergraduates for some sort of’midnight conference’,” recalls BYU Professor Ben Abbott of Plant and Wildlife Science. “They knew this would be their only shot to measure the interaction between extreme rain and a fresh fire.”

“In a few hours, we were ready to get all the equipment out and deploy,” Jones said. “We completed the installation of the last sampler that night, just as the first drops began to fall on the burn scars. The data we collected overnight was different from the other data we had sampled so far. I’ve never seen so many deposits in my life. — The stream was like chocolate milk. ”

After urgent sampling of 10 locations scattered across three river networks after rainfall, the group was surprised that wildfires and rains dramatically rebuilt the Utah Lake ecosystem.

For one thing, rain caused massive erosion in burned watersheds where wildfires consumed stable vegetation and litter. Sediment flux increased 2,000 times compared to unburned areas, creating a plume of ash and soil moving to Lake Utah visible from space. “That is, this single storm has moved as much sediment as a river would normally move in 100 to 200 years,” Abbott said.

The team also measured a 6,000-fold increase in particulate carbon and nitrogen washed away from burn scars.

In combination, these changes can cause problems for people and organisms that depend on the aquatic ecosystem of Lake Utah. Excessive nutrients such as nitrogen and phosphorus Harmful algal bloom In downstream waters, scientists call it “eutrophication,” which now affects about two-thirds of the Earth’s waters, including Lake Utah.

Megafire, hurricanes, water quality. Credit: Julie Walker

“this is Global crisis It’s off the radar of most people, but when asked by sustainability experts, they quickly rank eutrophication in terms of climate change and biodiversity loss, “said Abbott. .. There is also an immediate impact on society due to erosion. Big fire Canals and reservoirs used for agricultural water can be clogged, and carbon and nutrients can affect drinking water for years or even decades, which is costly to treat, ”explains Abbott. Did.

Scientists said these effects on the ecosystem were “warning.” In particular, the range of annual wildfires in the western United States has doubled since the 1980s. “If the fire happens in its natural form, it’s not a big deal,” said Sam St. Clair, a professor of plant and wildlife science at BYU. “But if you control fires and experience droughts and rising temperatures, the fuel load will increase and these catastrophic fires will occur, making the soil more prone to greater erosion events.”

“The average citizen needs to know better about the importance of a given fire,” St. Clair added, in good faith, to prevent large-scale fires that occur when forest fuels accumulate excessively. Some leaders often insist on extinguishing these fires. Of the fear of the people.

As with these findings, the biggest surprise of this study was that fire and rain did not prove to be the source of the greatest changes to aquatic ecosystems. Most studies of this type compare burnt and unburned areas of untouched “untouched” areas, but the BYU Group is strongly influenced by urban and agricultural development. A sample was also taken from. In doing so, they were able to compare the relative effects of the two disturbances of fire and human activity.

“We were really shocked that the direct effects of humans had a greater impact on nutrition and water chemistry than on wildfires,” said Abbott. “As much as the wildfires had a great impact, all parts of the city and agriculture were so nutritious that when compared to human-affected watersheds, they were burned and burned. I could hardly see the difference in the basins that did not. “

This is because almost everything we do, such as driving a car, washing the toilet, fertilizing the lawn, adds carbon, nitrogen, phosphorus and other nutrients to the environment. These pollutants have to go somewhere and often reach groundwater and rivers that supply water to Lake Utah.

“When a large wildfire breaks out, everyone can say,’Wow, look at this fire that burned 100,000 acres.’ However, we do not believe that the wastewater that comes out of wastewater treatment facilities every day has completely changed everything inside. Lake Utah. There is something we can do now to change what we are doing to the ecosystem, “Crandal said.

These proposed changes include improved wastewater treatment to remove nutrients and strategic strategies for land use and development as the population grows. “If we protect green spaces and vulnerable areas, we can grow the population in Utah County, basically maintaining our current footprint,” said Abbott. “It will be better for society, and for the creatures we share the planet with.”

This study was recently published in a journal PLOS ONE In a special issue on freshwater ecosystems.


Wildfire scars can intensify and even cause thunderstorms and cause catastrophic floods


For more information:
Trevor Crandall et al, Megafire affect the reactivity of stream sediment flux and dissolved organic matter, but land use governs nutrient dynamics in semi-arid watersheds. PLOS ONE (2021). DOI: 10.1371 / journal.pone.0257733

Quote: Megafire that caused more than a century of erosion near Lake Utah — but there’s more to the story, scientists (2021, October 25) said https://phys.org/news It is said that it acquired October 25, 2021 from / 2021-10-megafire-. Century-worth-erosion-utah.html

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Scientists say it’s a megafire that has caused more than a century of erosion near Lake Utah, but there’s more to it.

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