New study finds California is due for its “100 Year Flood”
California is commonly known for it’s earthquake risk and more recently, severe drought and wild fires. However, the tides are changing for California as a new study from UCLA predicts that potentially catastrophic flooding or what being called a “megaflood” is likely to happen. While there isn’t a clear timeline on when this “megaflood” may hit, the study from UCLA indicates that the possibility has been almost doubled thanks climate change.
According to an article from the New York Times, this mega flood will originate one winter in the Pacific ocean, near Hawaii. What will happen is, within the area where tropical air gathers around the Equator, atmospheric currents will pull out a long tendril of water vapor that will then be funneled towards the west coast. This vapor funnel - or vapor plume - will be hundreds of miles wide and nearly 1200 miles long. This massive vapor plume will crash into the mountains in California and be forced upward leading to weeks of rain and snow for the area.
The study warns that this megaflood could displace millions of people across the state and would be expected to bring feet of rain, and in some places more than 100 inches of rain fall. This megaflood would “swamp” all of Los Angeles as well costing nearly $1 trillion in overall economic losses.
According to UCLAs release around this megastorm event, apparently a storm like this has happened before and due to climate change, is expected to be even more severe as global temperatures rise. Severe floods have happened in California throughout the 20th century, with notable floods occurring in 1969, 1986 and 1997. However, the most notable and the flood that scientists are referencing today, occurred back in 1862. California’s Great Flood of 1862 stretched about 300 miles long and 60 miles across. According to the study, a similar flood today would displace anywhere from 5-10 million people, cut off major freeways for months and submerge major Central Valley cities including part of Los Angeles.
In 2010 researchers started examining the Great Flood of 1862 and called it the “ArkStorm Scenario.” To account for the effects of climate change that will inevitably worsen flood conditions, scientists from UCLA and the National Center for Atmospheric research have completed the first part of ArkStorm 2.0.
“In the future scenario, the storm sequence is bigger in almost every respect… There’s more rain overall, more intense rainfall on an hourly basis and stronger wind.” Daniel Swain, UCLA climate scientist
Although there hasn’t been a flood equivalent to that of 1862, the report outlines that climate modeling and the paleoclimate record — including river sediment deposits dating back thousands of years — shows that it typically happened every 100 to 200 years in the pre-climate change era. With the recent climate changes it is estimated that the chances each year that California will experience a monthlong megastorm is about 1 in 50. Should the earth continue to warm, those chances raise to about 1 in 30.
The last time government agencies studied a hypothetical California megaflood, more than a decade ago, they estimated it could cause $725 billion in property damage and economic disruption. That was three times the projected fallout from a severe San Andreas Fault earthquake, and five times the economic damage from Hurricane Katrina, which left much of New Orleans underwater for weeks in 2005. - New York Times
In terms of what to do next, there are a few ideas. Right now, further research and preparation is in the works and includes advanced flood simulations simulations supported by the California Department of Water Resources. Resaerches hope to be able to map out where the storm would hit and create statewide plans to mitigate the effects. These mitigation tactics could include letting water out of reservoirs preemptively, allowing water to inundate dedicated floodplains and diverting water away from population centers in other ways.
For now, we wait and see.
Sources:
https://www.usatoday.com/story/news/nation/2022/08/13/california-great-of-flood-1862-likerihood/10317968002/
https://newsroom.ucla.edu/releases/climate-change-makes-catastrophic-flood-twice-as-likely
https://www.cnn.com/2022/08/12/weather/california-megaflood-study/index.html
https://www.nytimes.com/interactive/2022/08/12/climate/california-rain-storm.html
https://www.foxweather.com/weather-news/california-megaflood-climate-change-drought-ucla
