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Mar/Apr 2011: Plausible and Inevitable: The ARkStorm Scenario

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Plausible and Inevitable: The ARkStorm Scenario

by Gary Pitzer


In California, “The Big One” is usually associated with a major earthquake that would severely disrupt the way of life for millions living next to or near the San Andreas Fault.

Now, scientists with the U.S. Geological Survey (USGS) have come forward with another “Big One” scenario, but instead of the ground shaking, in this case it would be underwater in many parts of the state after weeks of relentless rain. The exercise has a catchy name, “ARkStorm,” and has reminded people that California has a history of flooding and that the next big storm could be just around the corner. ARkStorm stands for an atmospheric river (“AR”) that carries precipitation levels expected to occur once every 1,000 years (“k”). The project is intended “to elevate the visibility of the very real threats to human life, property and ecosystems posed by extreme storms on the West Coast,” according to USGS. “For many people, the storms of 1969, 1986 and 1997 mean nothing,” said Dale Cox, chief of staff for the USGS Pacific Southwest Region who managed the project. “That's why we called it ARkStorm. We needed to scale the size of the storm.” In an ARkStorm scenario, a month's worth of rain dumps as much as 10 feet of water on the state, fed by a conveyor belt of tropical moisture. In addition to the expected damages (which include interruption of water conveyance), the storm has several public policy implications, most notable emergency preparedness. But there is also the “core issue” of “whether to pay now to mitigate, or pay a lot more later for recovery,” according to USGS.

ARkStorm rainfall totals in some places would “overwhelm” the flood protection system in many areas, USGS says. The Central Valley would experience a “hypothetical” flood 300 miles long and 20 miles wide, while Orange County, Los Angeles County, San Diego and the Bay Area would all be hit with serious flooding. “Both because of its large geographic size and the state's economic interdependencies, an ARkStorm would affect all California counties and all economic sectors,” the report, Overview of the ARkStorm Scenario, says.

The deluge of water would cause hundreds of landslides and property damage would run in the hundreds of billions of dollars. Coupled with factors such as agricultural losses, the costs of restoring pipelines and business interruptions costs, ARkStorm “could cost on the order of $725 billion, which is nearly three times the loss deemed to be realistic … for a severe Southern California earthquake, an event with roughly the same annual occurrence probability.”

The timing of the ARkStorm release was fortuitous. In December 2010, a series of storms slammed into California, hitting the southern part of the state especially hard and remind¬ing people about how quickly conditions can deteriorate. “An ARkStorm is plausible, perhaps inevitable,” the report says. “There may be no pattern that forces the storms to occur with clockwork regularity, so such an event could occur in any year.”

The image of a flood of biblical proportions is not unintentional, as the scale of anticipated precipitation would be on a scale previously unseen. California flooding references often point to the winter of 1861 when the city of Sacramento was 10 feet underwater.

USGS says a repeat of a storm that size is certainly capable of happening, just as the 1,000-year events in Pakistan last year and Australia in January. What's surprising, experts say, is that California isn't walloped by such super soakers more often. Until the next big storm arrives, the authors of ARkStorm say there is time for planners to consider the level of readiness and whether further investment is necessary.

“Although enhancing state flood protection is very costly; not doing so may be even more so,” the report says. “Enhancing urban sections of the state flood protection system to 500-year levels could realistically cost $10s of billions. Not doing so could realistically cost $100s of billions when such a storm occurs.”

Critics say a major flood is a crisis waiting to happen, because of the state's inability to come to grips with the nature of the threat. “The state has some of the most flood-prone land in the nation, much of which has been urbanized,” according to Managing California's Water: From Conflict to Reconciliation, a February 2011 re¬port by the Public Policy Institute of California (PPIC). “California faces increasing flood management challenges, with an extensive legacy of short-sighted flood infrastructure decisions, growing human and economic activity in floodplains, growing state liability for flooding, diminished long-term federal and state funding, continued separation of land and flood management, and climate change.”

PPIC calls for a new direction in flood management that recognizes the risk posed to communities rather than concentrating on building stronger levees to protect existing and prospective development.

“Flood management in California has had a historical tendency to over-invest in a few tools to increase flood protection, without regard to flood vulnerability,” the PPIC report says. “The unintended consequence of these investments is often an increased, rather than a decreased, flood risk.”

PPIC's warning touches upon a familiar problem - urban development in floodplains. Pal Hegedus, vice president of RBF Consulting and chair of the Floodplain Management Association, said there is an “inherent conflict” with the concept of having a short commute and “smart cities” developed within the floodplain at the same time there is a flood risk to these urban areas. Ultimately, a workable middle ground has to be found.

“We can't all move out to the foothills,” he said. “It's a very complex issue.”

In 2005, Hurricane Katrina in New Orleans vividly demonstrated the destruction that comes with levee failure. Cognizant of the risk facing the Central Valley, lawmakers in 2007 required new development to surpass the federal flood protection standard by requiring a 200-year level of protection.

In 2012, state officials are scheduled to approve the Central Valley Flood Protection Plan for the Sacramento-San Joaquin Valley that aims to provide 200-year flood protection for urban areas (The level of flood protection, i.e. 50-year, 100-year, reflects the probability of a particular-sized storm occurring in a given year. A 100-year storm has a 1 percent chance of occurring each year.) Implementing language for the plan in the California Water Code notes that despite structural improvements, flood risks will remain for those living in the Central Valley floodplains and that “making those flood risks more apparent will help ensure that Californians make careful choices when deciding whether to build homes or live in Central Valley floodplains, and if so, whether to prepare for flooding or maintain flood insurance.”

The difference between preparing for a 200-year storm and the epic event described by USGS is not insignificant and calls into question what can reasonably be defended against. ARkStorm planners acknowledge that “California flood protection is not designed for an ARkStorm-like event.” While many improvements have been made, “the state flood protection system is not perfect.”

State officials acknowledge only a certain level of safety is attainable.

“The storm they are talking about is quite a bit bigger than we designed for our flood control facilities,” said Jay Punia, executive officer of the Central Valley Flood Protection Board. “It's a fact that due to economic considerations, we can't provide ultimate protection for such a large event.”

This issue of Western Water examines the scenario known as the ARkStorm and the extent to which state and local agencies are making improvements to California's flood infrastructure.

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Editor's Desk

When it comes time to read the daily water news headlines these days, I find myself reaching for my computer keyboard or smartphone more and more. As a former journalist, I am amazed by the transformation in the news business the past decade. But even if the physical newspaper is becoming scarcer (The New York Times just announced an electronic subscription) the public continues to be hungry for news and the industry is slowly adapting.

For the Water Education Foundation, our strategy has been twofold: continue to produce our well-written, well-researched and printed publications such as Western Water, River Report and the Layperson's Guide series, but to also reach out in the virtual world. We've taken some modest steps; Western Water is available for a fee as a downloadable PDF while a virtual River Report can be found online for free at www.watereducation.org.

For daily news, we encourage you to turn to www.aquafornia.com - our California water news blog. We purchased Aquafornia in 2010 after a two-year partnership with its original creator, Chris Austin, a.k.a. “Maven,” who established the site simply because she was fascinated with water - she even takes family vacations to view aqueducts and water projects.

Our goal for Aquafornia is simple - to post the latest news on a wide range of water issues, and present a balance of viewpoints through traditional and non-traditional sources - press releases, news stories, official statements, editorials and selected blogs. Our editorial policy is posted on Aquafornia.

Aquafornia also includes a reference desk where you can find important background information on California water, salinity issues in the Central Valley, the Delta and water conservation tips. Last year, we completed a slideshow about the State Water Project, which features 203 slides that allow viewers to trace the water from Oroville Dam to Lake Perris. Stops along the way help the viewer learn about the Delta, the various branches of the California Aqueduct, water use in California and more.

Beyond the immediate news of flood and drought, litigation and legislation, the Foundation strives to provide more information on key topics such as flood, the topic of this issue of Western Water. News articles about the flooding in Southern California, atmospheric rivers and the ARkStorm scenario have been featured recently on Aquafornia. Writer Gary Pitzer researched these issues and delved behind those headlines to develop this issue of Western Water, which also looks at what flood management authorities are trying to do to strengthen levees and prepare for large storm events. The article also looks at the important issue of funding such improvements, always a big issue - especially in these tough economic times.

I hope you'll continue to take your news on the road with you - either with a copy of the latest Western Water or River Report tucked into your briefcase or with your smartphone in your hand to read Aquafornia. At this point, I am pleased to announce we will soon be launching an iPhone app for Aquafornia that will make it even easier for you to keep up with the latest news. Stay tuned for more on the Aquafornia app and our other programs.

- Rita Schmidt Sudman


In the News

Ag Interests, Fish and Game Reach Accord in Flap Over Striped Bass Management

A dispute regarding the impact of non-native striped bass on endangered fish species in the Sacramento-San Joaquin Delta was resolved March 17 with a settlement agreement that requires the state to work with federal scientists to alter management of striped bass.

Some Central Valley water districts had sued the Department of Fish and Game (DFG) claiming its promotion of striped bass fishing was harming native salmon and smelt in the Delta through predation. Plummeting salmon and smelt numbers have translated into less water pumped from the Delta.

In an agreement brokered in federal court, the water user group Coalition for a Sustainable Delta and the state agreed that a plan must be developed to address the harm caused to native fish by striped bass, which were introduced into the estuary more than a century ago. Striped bass are voracious predators, responsible for the loss of a significant number of salmon. According to DFG, the take could be between 25 to 50 percent of both the endangered Sacramento River winter-run and the threatened spring-run Chinook salmon.

The regulation to be developed by DFG, the National Marine Fisheries Service and the U.S. Fish and Wildlife Service will recommend a change to striped bass sport fishing that will likely allow more of the fish to be taken from the Delta. Current rules allow for the taking of two striped bass per day - none smaller than 18 inches.

Those that depend on water pumped from the Delta have long argued that several factors, and not just pumping, have caused the decline in native species.

“We applaud the Department of Fish and Game for coming together with us to develop a solution to the significant negative impact striped bass have on the Delta ecosystem,” said Michael Boccadoro, spokesman for the Coalition for a Sustainable Delta. “Predation by non-native species such as the striped bass is one of the most clear-cut stressors on endangered Delta fisheries and addressing this problem is a vital step toward creating a sustainable future for the Delta estuary.”

Any change to that bass limit would have to be approved by the California Fish and Game Commission.

The California Sportfishing Protection Alliance (CSPA), which opposed the settlement, said the controversy about striped bass is merely an attempt to deflect attention away from the export pumps that have “devastated” the salmon and smelt.

“CSPA was looking forward to trial because the evidence in the record did not support the conclusion that striped bass predation caused population level effects on salmon and smelt,” said Bill Jennings, executive director of CSPA. “Unfortunately, feeling the pressure of escalating legal costs, DFG caved and cut a deal. The catastrophic decline of the salmonid and pelagic fisheries of the Central Valley is emblematic of DFG's longstanding failure to fight for fisheries.”

- Gary Pitzer