What are ARk storms and the chances of a scenario similar to California’s 1862 flood

SAN FRANCISCO, California. – The possibility of the arrival of a mega-storm dumping immeasurable amounts of rain has recently been discussed, but what some people don’t know is that this has happened before.

During the last major flood in California, there were 45 days and 45 nights when water fell from the sky in torrential rains that seemed to have no end. It was Christmas Eve 1861, and for more than six weeks, Californians experienced something they had only read or heard about in biblical accounts of the flood.

A series of devastating storms battered the country’s west coast, causing extreme damage to California. When it was all over, nearly 30 inches of rain had fallen on the city of San Francisco, the streets of Sacramento resembled raging rivers, and a lake 300 miles long by nearly 20 miles wide had formed in the Central Valley.

Flooding forces the governor to “paddle” to the Capitol

Sacramento in 1862
Photograph of K Street looking east from 4th Street (right) and illustration of K Street looking east from Front Street (left). Credit: Courtesy of the Center for Sacramento History.

According to the Sacramento History Museum, this storm transformed the Central Valley into an inland sea and severely flooded Sacramento.

The story goes that even Governor Leland Stanford had to take a rowboat to his inaugural events in January 1862.

“Leland Stanford took a rowboat through the streets of Sacramento to the Capitol, then on I and 7th Street from his mansion at N and 8th Street for his inauguration as the eighth governor of California,” the museum stated.

On Jan. 10, 1862, the levee broke along the American River near 31st Street in Sacramento at the exact location where the levee broke a month earlier, on December 9, immediately flooding the lower parts of the city.

“California was experiencing, at this time, a 200-year storm that dumped 24 inches of rain in January alone,” the museum noted.

1862 flood had severely affected Central Valley

According to historical accounts, by the 1862 storm, California’s Central Valley became a great inland sea. For Sacramento, this flood became worse than any flood it had experienced in the past.

“Flood waters spread throughout the city. Merchants moved goods from their stores to platforms erected above the line of supposed danger. Livestock owners drove horses, mules, and cattle to the I Street and Front Street levees. Citizens moved themselves and their belongings to the upper floors of houses,” the museum notes.

They used boats to move in the flood

History documents that boats became the primary means of transportation to get around the city.

The museum notes that the water on J and K Streets was four to five feet high.

Despite the magnitude of the flood, the local newspaper of the time, The Sacramento Daily Union, reported that only four people drowned in the city.

This is because Sacramento had become accustomed to how to react during floods and had safety procedures in place.

Legislature moved to San Francisco due to flooding

The museum notes that Sacramento remained flooded for three months, and because of this, the Legislature moved to San Francisco for the remainder of the session, this in late January.

In March 1862, William Brewer, a federal land surveyor assisting with the first geological survey of California, got a strong impression of the flood damage while visiting Sacramento.

“I don’t think the city will rise from the impact, I don’t see how it can. However, it has a brighter side. No town can withstand calamity as much as this town. According to a quote compiled by the museum, they are used to it,” Brewer said.

The account of the catastrophe was documented in the book “Up and Down California” written by Brewer, who, in his notes of January 19, 1862, notes the following: “Sacramento and many other cities are flooded (…) The great Central Valley is under water, thousands of farms are flooded, and cattle are dying and drowning”.

Rebuilding Sacramento after flooding

But despite Brewer’s ominous words, Sacramento rose after the flood.

Henceforth, the town began raising its buildings and streets to save the city from further flooding.

In addition, the confluence of the American River with the Sacramento River was diverted one mile north, and a much stronger levee was built.

Sacramento’s official motto is Latin for “Urbs Indomita,” meaning “indomitable city,” to emphasize the heroic character its residents have had to demonstrate in adversity such as this.

The great Sacramento flood in 1862
This 1862 photograph shows the intersection of “K” and “4th” Streets in downtown Sacramento during the Great California Flood. Credit: California State Library

A new study anticipates a megastorm

To date, the natural disaster Californians fear most is the so-called “The Big One.” However, a new study warns that climate change has raised the possibility that the state could be hit by a mega-storm that could last for more than a month, leaving large regions of California submerged under water and generating up to $1 trillion in economic losses.

Daniel Swain, a climate scientist at the University of California at Los Angeles (UCLA), is one of the studies published in the journal Science titled “Climate change is increasing the risk of a mega-flood in California.” The expert explained during a forum on Twitter that the “chances of an event capable of producing catastrophic floods” have doubled in recent years.

The model presented updates the previous data and scope of what was known as the ‘ARk megastorm’ (ARk comes from “atmospheric river 1,000 [k] storm”), which they now refer to as ‘ARk 2.0’, a severe storm and flood scenario reimagined for the era of climate change.

‘ARk 2.0’: storms for 30 consecutive days

Representation of Noah's Ark big storm
Representation of the Noah’s Ark big flood in biblical times. The image attempts to illustrate the scenario that could be experienced in California due to a flood.

The scenario drawn by the report is close to apocalyptic, a storm so immense that it would cause devastation in California three times greater than the damage projections made for the mega-earthquake known as “The Big One,” for which the state is still preparing.

The effects of climate change led scientists to reanalyze the possible arrival of a storm of biblical proportions that would lash California for weeks at a time and cause economic losses equivalent to one trillion dollars. According to his calculations, these climatic events occur every 100 to 200 years, and it has been more than 160 years since the last one.

This hypothetical ‘ARk 2.0’ storm, similar to some that occurred centuries ago, would hit the West Coast so hard that the Central Valley of California would be inaccessible to the rest of the United States. The rainfall, the study explains, would extend over several weeks and exceed levels that many areas experience only once every 500 years.

The scientists’ projection estimates that all flood control systems in California would be quickly overwhelmed during the event. In the Central Valley, for example, an area 300 miles long by 20 miles narrow would be inundated, but the damage would be even more significant in coastal regions. Orange, Los Angeles, and San Diego counties, as well as most of San Francisco Bay, would be completely underwater.

In addition to copious storms, extreme winds would increase the scale of the catastrophe. In some regions of California, gusts would reach Category 3 hurricane strength with averages of 125 mph; in the rest of the state, wind speeds would not drop below 60 mph. Meanwhile, the combination of rain and hurricane-force winds would facilitate the proliferation of hundreds of mudslides that would wash away roads, highways, and homes alike.

Projection of flooding in the California Central Valley in the scenario of an 'ARk' storm.Credit: USGS
Projection of flooding in the California Central Valley in the scenario of an ‘ARk’ storm. Credit: USGS

What is an ‘ARk’ megastorm, and when will the next one arrive?

Scenarios like the one described above have been repeated in California at least seven times in the last 2000 years. Today, scientists and weather experts have also given them a name: ‘ARk’ megastorms.

These megastorms are a series of mighty atmospheric rivers that gather water vapor in the Pacific Ocean and move it up the west coast of the United States, with the potential to cause devastation three times greater than that of a megathunderstorm.

Despite all the scientific and technological advances today, it is still impossible to accurately predict a phenomenon of this nature in the same way that tropical storms, cyclones, and hurricanes are predicted. However, experts agree that they can and will happen again.

“We have geologic evidence collected from subsurface deposits that indicate that storms even greater than the 1862 storm have occurred once every 300 years. In the last 1,800 years, we have records of six similar events. With this data, we believe this megastorm will occur about once every 100 to 200 years,” explained Professor Lucy Jones, chief scientist of the USGS Multi-Emergency Demonstration Project.

To date, it has been more than 160 years since the last mega-storm ‘ARk’ unleashed its fury on California, so much so that it bankrupted the state. As with the mega-earthquake called “The Big One,” scientists agree that we are getting closer and closer to the threshold for the next deluge, or “The Other Big One,” to hit the Golden State.