Outside my lab near the Donner Pass in Sierra Nevada, California, new animal tracks are on the snow after winter hibernation, birdsong soars in the air, and the creek flows heavily with water from the melting snow. Spring came anxiously early in the Sierra Nevada.
Last week, I joined teams of other scientists collecting the most important measurements of snow cover in the Sierra Nevada from more than 265 locations across the state. This measurement usually marks the transition from the snow accumulation season to the melting season and contains the most snow of each measurement throughout the year. However, the results of 2022 confirmed what those of us who watched the drought in the state feared: the snow cover in California is now 39 percent of its average, or 23 percent lower than the same point last year . This signals a deepening drought – already the worst in the western United States in 1,200 years – and another potentially catastrophic fire season for much of the West.
Many people have a rather simplistic view of drought such as lack of rain and snow. That’s right – to some extent. What it does not take into account is human activity and climate change, which are now dramatically affecting available water and its management. As more frequent and large forest fires and prolonged dry periods destroy the land, our most important water management tools are becoming less accurate. At the same time, relying on these models to try to get the most out of the little water we have is becoming increasingly problematic.
Drought can last for several years or even more than a decade, with varying degrees of severity. During these types of prolonged droughts, the soil can become so dry that it absorbs all the new water, which reduces runoff to streams and reservoirs. The soil can also become so dry that the surface becomes hard and repels water, which can quickly cause rainwater to spill out of the ground and cause flooding. This means that we can no longer rely on relatively short periods of rain or snow to fully alleviate drought conditions, as we have done with past droughts.
Many storms with almost record amounts of rain or snow will be needed in a year to make a significant dent in drought conditions. October was the second snowiest month, and December was the snowiest month in the history of the snow lab since 1970, thanks to two atmospheric rivers that hit California. But the extremely dry periods from November and January to March left us another year with snow cover, rain and runoff below average.
This type of festive or hungry winter with large storms and long, severe dry periods is expected to increase as climate change continues. As a result, we will need several above-average rainy and snow years to make up the difference, rather than successive major events in one year.
Even at normal or above average rainfall years, changes in the earth’s surface are another complication. Massive forest fires, such as those we have seen in the Sierra Nevada and the Rockies in recent years, are causing dramatic changes in the way snow melts and water, including rain, drains from the landscape. Loss of forest roofs from fires can lead to higher wind speeds and temperatures, which increase evaporation and reduce the amount of snow water reaching the tanks.
Climate and the world are changing. What challenges will the future bring and how should we respond to them?
Like prolonged drought, fire also changes soil properties and can create sudden floods during intense periods of rain. These changes in the landscape, holiday or famine patterns, and increased demand for water supply make water management in the West an uncertain and difficult task.
One of the most important tools for managing water during periods of drought are models developed by various state and federal agencies such as the Hydrological Development Service of the National Weather Service, the Army Corps of Engineers, and the California Department of Water Resources. Yet these models suffer from the same simplistic view of land and water and are in dire need of an update.
Earth’s surfaces, melting patterns and climate have changed since the development of many of these models, which means that they lack important parts of today’s water puzzle. What has prevented model updates for decades is the shrinking funding for science and engineering.
Models may not be able to reliably inform water managers how much rain and snow will flow from the ground into tanks, which could mean a serious shortage in the worst case scenario. Given the declining levels of reservoirs and scarce snow cover in recent years, discrepancies between the expected amount of water and what is arriving may mean the difference between the availability of water in taps and the drying up of entire cities.
We look down at the barrel of a loaded weapon with our water resources in the West. Instead of investing in bulletproof vests, we hoped that the trigger would not be pressed. Current water monitoring and modeling strategies are not enough to support the growing number of people in need of water. I am worried about the next week, month and year and new problems that we will inevitably face as climate change continues and water becomes more and more unpredictable.
It is time for politicians who allocate funding to invest in updating our water models, instead of maintaining the status quo and hoping for the best. Large-scale investments in the agencies that maintain and develop these models are essential to prepare for the future of Western water.
Better water models ultimately mean more accurate water management, and this will lead to greater security and availability of water for the millions of people who now depend on changing water supplies. It is an investment in our future and, moreover, an investment in our continued ability to live in water-scarce regions in the West. This is the only way to ensure that we are prepared when the shutter button is pressed.
Dr. Schwartz is a leading scientist and station manager at the University of California, Berkeley, Central Sierra Snow Laboratory.
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