Atmospheric Rivers: Hydrology, Economics, & Climate Change
Intense downpours of rain lead to flooding, which causes thousands of dollars worth of damages to a community. This photo shows the flooding damages in Sonoma County in 2019.
If you are from California, there is a good chance that you are familiar with droughts. From switching to a drought-tolerant lawn and the rise of astro-turf, to shorter showers and no at-home-car-washes, the scarcity of water in this state is an everyday reality for millions of Californians. So it seems reasonable when Californians get excited for a storm that is predicted to bring much-needed rainfall to the state. While getting enough rainfall is critical for both human activities and ecological processes, there is rising concern of the ability of our current infrastructure to handle heavy rainfall.
Atmospheric rivers, also known as the pineapple express, are air currents that carry water vapor from the tropics to the West coast. They are large rivers in the sky that produce powerful storms-- they can transport up to 15 times the volume of the Mississippi River. In California, AR’s account for half of California’s rainfall, making them a critical component of the state’s water supply. While normal amounts of rainfall usually result in water running off into natural water storage systems, the problem with AR is that intense rains can come down too quickly, and wash into the ocean instead of water storage systems, causing flood situations, or landslides on hills that lack plant coverage.
As with most physical processes on Earth, the warming of the climate will have serious implications on AR’s: U.S. Geological Survey hydrologist Mike Dettinger says, “When the atmosphere is warmer, it holds more water vapor, so there is a huge increase in the number of these atmospheric rivers.” Likewise, the intensity of storms is expected to increase with global warming.
In a study published in Science Advances, researchers found that “from 1978 to 2017, atmospheric rivers accounted for $42.6 billion in flood damage in 11 Western states... That’s roughly $1.1 billion in damage done by atmospheric rivers every year.” The current infrastructure in the Western states wasn’t built to withstand the increasing intensity of atmospheric rivers, and is resulting in expensive damages.
Atmospheric rivers also pose a threat to sea ice; when AR bring warm moist air from the coast of South America to polar regions, the air creates holes in the ice by melting it. The melting of sea ice comes along with its own implications, like sea level rising and affecting low-lying areas. Both West Antarctic land ice and ice shelves as well as Antarctic sea ice have been affected by AR conditions. When these ice holes form, they have their own repercussions, such as affecting the timing of algae blooms, which in turn affects marine ecosystems.
While California is a desirable place to live, the constant concern of climate change-related impacts is a factor worth noting for those who decide to live here. Dealing with droughts, wildfires, mudslides, air pollution, and now intense atmospheric rivers does take quite a toll on a person. However, if we update our infrastructure now, we can mitigate flood disaster impacts on communities. Perhaps we can find ways to create new job opportunities as we implement new technologies, infrastructures, and strategies for dealing with the expected climate change impacts. Does this responsibility lie in states, or the Federal government’s hands? Or, should we focus our efforts on finding ways to capture these intense downpours of water from AR into water storage systems in order to make water a less scarce resource?
One potential solution could be permeable pavement or concrete. A study by the USGS defines permeable pavement as “... a porous urban surface composed of open pore pavers, concrete, or asphalt with an underlying stone reservoir. Permeable pavement catches precipitation and surface runoff, storing it in the reservoir while slowly allowing it to infiltrate into the soil below or discharge via a drain tile.” This study also infers that permeable pavement can reduce concentrations of pollutants in the water. While the option of permeable pavement is still being researched, it does provide a hopeful solution for harnessing rapid downfalls from AR’s.
In this scenario, being proactive instead of reactive is key. If we can find ways to gain understandings of AR as a physical phenomenon and learn more about predicting them, we have a better chance of preparing for and mitigating potential disasters. Luckily, California is a progressive state who tries to be ahead of the game; in California’s Legislature’s 2019-2020 budget, the California Department of Water Resources received $9.25 million toward funding for research into atmospheric rivers. Curt Aikens, general manager of Yuba Water Agency in California, says “This essential investment in public safety and sustainable water management shows true leadership and is vitally important as California works to address the challenges of climate change,” about the investment.
