Explained: Can atmospheric river-induced floods help with California’s ‘exceptional’ drought?

The US state of California has experienced a number of mega droughts over the years, including just last month, prompting officials to impose water restrictions across the state with limited supplies for vital farmland. In contrast, one of the driest states in the country, after a series of storms, is now experiencing deadly flooding, landslides and uprooted trees, which have affected road travel and left thousands without power, due to the rains dense and strong winds. This is attributed to a superimposed weather phenomenon called “atmospheric river” and “bomb cyclone”.

As recently as last week, several counties across the state were suffering from “extreme” drought, the most severe classification given by the Drought Monitor in the country. However, the latest storms have killed at least 17 people since the start of this year, California Gov. Gavin Newsom said Tuesday, as the state city of San Francisco witnessed a hailstorm and the small town of Montecito experienced flooding. fast.

Has the rain helped the drought situation so far?

In recent weeks, the state has seen six tornadoes in recent weeks and is poised to experience at least three more in the coming week, Newsom said. According to officials, Central California, including the San Francisco Bay Area and the Sacramento Valley, has seen the most water and rainfall is nearly 140 percent above average for this time of year.

This has filled many state reservoirs, which are usually below average this time of year, and will help irrigate farmland and supply water to millions in coastal cities. According to the US Drought Monitor, the storm appears to have taken at least seven percent of California out of the most severe categorization.

In addition, a hydrologist in charge of the California Nevada River Prediction Center, Alan Haynes, said this amount of rain puts the state in good shape for at least next year, the Associated Press reported. However, it’s still too early to tell what the next few months will look like, given that the storm hasn’t dumped as much water on northern California.

Since the rainfall is not consistent and even not striking everywhere. The reservoir in Shasta Lake had risen from 55 percent over Christmas to 67 percent earlier this week, and while that’s an improvement, it’s still below historical averages given the state’s prolonged water shortage, Haynes said.

Will this surplus change anything in the water supply in the long run?

Several reports citing experts and scientists said that the widespread drought in California will not return due to these atmospheric rivers and bomb cyclones and it may also take consecutive years of similar weather trends of above-average rain and snow to have a lasting impact. This comes despite at least 90 percent of the state’s population being affected by the floods.

Notably, last year the state witnessed its third year of severe drought, which was also the driest on record, and while it is now soaking up much-needed water, some experts say this amount of rain will help, but not have a lasting impact. Furthermore, they also indicated that this rain and snow will not be enough to fix some of the long-term water problems facing California along with much of the western US with unfavorable precipitation trends which are getting worse due to climate change.

Speaking to the BBC, Jay Lund, a professor of civil and environmental engineering at the University of California, Davis, said that while the current storm has certainly replenished some of the state’s water supply, it’s always good to see rain in California. However, he noted that since the state’s weather is one of extremes, the coming years may witness drier weather.

Why don’t these extremes work?

While one might think that the drought-stricken state receiving large amounts of water would be a good thing, it’s actually the opposite, as some reports suggest that a flood during a time of drought could make the situation worse. A report from Vox compares this phenomenon to over-watering a plant which after a while can’t handle absorbing so much water. Therefore, eventually this rain turns into flooding with the risk of uprooting trees.

During a press conference last week, California Department of Water Resources (DWR) Director Karla Nemeth also explained that moving from one extreme weather event to another has put the trees under stress as “after three years of intense drought , the ground is saturated and there is a significant chance of trees falling which will create significant problems.”

Additionally, during these droughts, tree roots that are supposed to absorb water become less sponge-like, and with weaker roots, they are more likely to be swept away by storms. Experts have also pointed out that California does not have the infrastructure to support the storage of this much water due to limited reservoir capacity, therefore, much of this water goes into the ocean.

Simply put, “California’s system was built for a climate that we no longer have,” said Laura Feinstein, who directs climate sustainability and environmental work at a San Francisco-based nonprofit called SPUR. It was also said in the context of water coming from snow which is its own type of reservoir.

In this case, the snow usually melts in the reservoir and supplies the residents with water during the summer and autumn, however, since the snowpack due to climate change is now melting faster and the reservoirs are not able to capture enough water. Additionally, climate change has caused extreme weather events, which are also creating drier and hotter conditions where water is forced to evaporate more quickly.

So what can be done to mitigate this problem?

Climate scientists said part of the solution to these problems could be levee retreat, which would allow rivers to flood safely and not only collect more water, but also do so while ensuring the safety of the land that surrounds it.

Climate scientist Peter Gleick, who spoke to CNN, said that while the layers have protected communities in the past, they are not designed for the extreme weather challenges posed by climate change today. Therefore, he suggests infrastructure changes that would allow people to capture more floodwaters and store them in underground aquifers when water supplies are drying up.

Additionally, Gleick also told CNN, “We need to design flood insurance policies to encourage people to move out of flood plains so we can open up those flood plains, so when we get those floods, they will be less damaging.”

However, to do this, many communities would have to be relocated and also require a significant reconstruction of the existing infrastructure, which does not seem feasible. Notably, these underground aquifers to this day still remain vital to the state’s central valley and are said to be drying up.

(With data from agencies)

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