The Great Flood of 1862 Could Repeat
- New research suggests climate change is increasing the likelihood of a massive “mega-flood” in California, similar to the Great Flood of 1862.
- This disaster, caused by more than 40 days of constant rain, resulted in the death of 4,000 people.
- Floodwaters from this disaster created an “inland sea” 300 miles long and 60 miles wide in some places.
A new study raises concerns about climate-change-fueled floods dropping massive amounts of water on drought-stricken California — an unlikely scenario that has happened before.
While intense droughts, wildfires and earthquakes are usually the top concern across the West, the study released Friday warned of another looming crisis in California: “Megafloods.” He notes that climate change is increasing the risk of flooding that could overwhelm cities and displace millions of people across the state. It says a month-long extreme storm could bring feet of rain — in some places more than 100 inches — to hundreds of miles of California.
Although the script may sound like something out of a movie, it’s happened before.
California has experienced severe flooding throughout the 20th century, including in 1969, 1986 and 1997. But a flood from further back in time – the Great Flood of 1862 – is observed by researchers as the threat to California is growing day by day.
Although it happened 160 years ago, the flood – considered a “megastorm” for its historic rainfall covering huge swathes of the state – illustrates that the threat is not merely theoretical.
In fact, UCLA researchers who study “megafloods” say such storms typically occur every 100 to 200 years.
Researchers are sounding the alarm because a flood of this magnitude today would have far more devastating effects in a state that is now the most populous in the country.
And the great flood of 1862 was also preceded by drought.
How bad was the great flood of 1862?
Intense thunderstorms battered central California “virtually relentlessly” from Christmas Eve 1861 through January 1862, Scientific American recounted in a 2013 article on “The Coming Megastorms.”
The flow of water created “an immense inland sea … an area at least 300 miles long,” leaving central and southern California underwater for up to six months, according to the magazine. Floodwaters stretched up to 60 miles in diameter, UCLA researchers wrote in their recent flood hazard study.
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“Thousands of farms are entirely under water – cattle are starving and drowning,” scientist William Brewer (author of “Up and Down California in 1860-1864”) wrote in a letter to his brother, quoted by Scientific American. “All the roads in the middle of the state are impassable; therefore all the mails are cut off. The telegraph does not work either. In the Sacramento Valley, for some distance, the tops of the poles are under water.”
About 4,000 people died and a third of all state assets were destroyed, including a quarter of its 800,000 cattle, which drowned or starved to death, the SFGate news site wrote in a statement. retrospective earlier this year.
The Great Flood of 1862 would be much worse if it happened today
The area that was under water in 1862 is home to many more people today than it was then – it’s home to some of California’s fastest growing cities, including Bakersfield and Sacramento.
Back then, the state’s population was around 500,000, but today it is nearly 40 million. “If a similar event were to happen again, parts of cities such as Sacramento, Stockton, Fresno and Los Angeles would be under water even with the current extensive collection of reservoirs, levees and bypasses,” said researchers who worked on the study of flood risks published on Friday. said in a statement.
The resulting disaster would cause damage estimated at $1 trillion, the largest disaster in world history, they say.
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And the effects would go beyond central and southern California, said Daniel Swain, a UCLA climatologist and study co-author. “All major population centers in California would be affected at the same time – likely parts of Nevada and other adjacent states as well,” he said.
Major freeways such as Interstate 5, which runs along the Pacific coast from Canada to Mexico, and I-80, which runs through California through San Francisco and Sacramento, would likely be closed for weeks or months, a- he declared.
The ripple effects would impact the global economy and supply chains.
What causes mega floods?
Atmospheric rivers are long streams of water vapor formed about a mile above the Earth. They can “carry as much water as 10 to 15 Mississippi rivers from the tropics and across mid-latitudes,” wrote Michael Dettinger, research hydrologist for the US Geological Survey, and Lynn Ingram of the University of California at Berkeley, Professor of Earth and Planetary Sciences, in Scientific American.
When crossing the Pacific Ocean and hitting the Sierra Nevada, “it is forced, cools and condenses into large amounts of precipitation,” they wrote.
Warming temperatures make extreme storms more likely – with more runoff, researchers say. In a 2018 study, Swain estimated there was a 50 to 50 chance that a mega-flood the size of the Great Flood of 1862 would happen again by 2060, Popular Science reported. “It would essentially flood land that is now home to millions of people,” he said at the time.
The new research suggests that climate change has already doubled the likelihood of extreme storms, and that each additional degree of global warming increases the likelihood of a mega-flood.
Research continues on the potential effects of flooding and how to prepare for it. Keeping the issue alive in the minds of Californians is important as drought, wildfires and earthquakes get all the attention, Swain said.
“There’s the potential for bad wildfires every year in California, but many years go by without news of major flooding,” he said. “People forget that.”
Follow Mike Snider on Twitter: @mikesnider.
USA Today
