it was one of those Wettest year Been in California since records began. From October 2022 to March 2023, the state was hit by 31 atmospheric rivers. This river is a huge band of water vapor that forms over the Pacific Ocean and becomes a fire hose when it reaches the West Coast. What surprised climate scientists was not the number of storms, but their strength and frequency. The heavy rains shocked the state’s water system, which had just experienced its driest three years in history, causing flooding, mass evacuations and killing at least 22 people.
sway between extreme wet and dry While it’s typical for California, last winter’s rains may have been intensified by climate change and were almost unmanageable. In addition, the arrival of El Niño is likely to bring even more extreme weather to the state. This would make life extremely difficult for dam managers, who are tasked with capturing and controlling much of the state’s water.
Like most of the world’s 58,700 large dams, the one in California was built for yesterday’s more stable weather patterns. But as climate change strains the world’s water systems, affecting rainfall, snowmelt and evaporation, it’s becoming harder to predict how much water will reach dams and when. Dams either become increasingly depleted and unable to maintain power and water supplies to communities, or they become full and are forced to release more water than desired, creating a risk of flooding downstream. .
But at one large dam in Northern California, managers are demonstrating how to not only survive these volatile and intense storms, but take advantage of them. Built in 1970, management at New Buller’s His Bar uses a new forecasting tool that gives unprecedented insight into the size and strength of upcoming storms and allows them to strategize how to deal with the rain. I went into last winter equipped with this.
First, rain replenishes reservoirs, a typical behavior after long droughts. Then, as more storms developed at sea, we were convinced that more rain was coming, so we made the difficult choice to release some of this precious reserve through hydroelectric turbines. “I was a little nervous at first,” says John James, director of resource planning for the Yuba Water Authority in Northern California. Soon fresh rain proved the move. The new Bullard’s bar finished the winter with an increased water supply, a 150% increase in power generation, and a clean safety record. This strategy offers a glimpse into how hydropower can adapt to climate change with better forecasting.
Modeling studies have long suggested that better weather forecasts are invaluable to dam managers. Now this is confirmed in real life too. New Bullards Bar is one of six pilot sites in collaboration with the U.S. Army Corps of Engineers to test how cutting-edge predictions can be used to optimize real-world operations. is. Initial testing of the method, called predictive reservoir operations, allows operators to secure reserves 5 to 20 percent above the reservoir’s normal capacity, said Cary Talbot, who leads the Army Corps initiative. He says he has gained the confidence to do so.
For Talbot, FIRO could represent a paradigm shift in how the Corps and others operate dams. Historically, dam managers under the Army Corps have had to ignore weather forecasts and respond only to rain and snow that is already on the ground. This rule goes back to the notorious fickleness of traditional weather forecasting. This means that if managers make bad bets on expected weather events, there can be dangerous consequences. But in practice, this forces pilots to react slower than instinctively, said Riley Post, a University of Iowa researcher who spent more than a decade as a hydraulic engineer for the Corps. For example, a near-full reservoir might be expected to store water when heavy rains approach.
However, recent developments have increased the reliability of atmospheric river forecasts, especially on the West Coast. A leap in computing power has enabled more powerful climate and weather modeling than ever before. To inject data into these models, scientists led by the Scripps Institution of Oceanography have, since 2016, launched reconnaissance flights over targeted atmospheric rivers, where they fly objects shaped like Pringles cans. Dozens of dropsonde sensor packs were dropped. The result is a detailed profile of the storm’s strength, size, and intent, which can then be input into FIRO.
These reports are not clairvoyant. All weather forecasts involve some degree of uncertainty. But dam managers have greater confidence in when, where and how much water reaches their basins, and can take a more “surgical” approach to storing and releasing water, he said. Post says.
And if you know how much time you have, you can also make the most of your existing water. Prado Dam is an old facility built in 1941 to protect Orange County from flooding, but it also provides water to 25 groundwater recharge stations. Forecasts this winter showed the storm tracking its path at intervals. So operators pulsed water from the dam into the reservoir at an optimal rhythm, giving it time to permeate the landscape. Adam Hutchinson of the Orange County Water District, which manages the groundwater recharge system. publicly stated in July These actions provided an “unprecedented” boost to water supplies during the “drought period we know is coming.”
