Management of water resources in the future of low to snowless

Credit: PIXTA / CC0 public domain

Mountain snow cover around the world is declining, and as the Earth continues to warm, climate models show that at some point in the next century, snow cover will shrink dramatically and disappear completely in certain mountains, including the western United States. I even predict that there is a possibility. A new study, led by researchers at Lawrence Berkeley National Laboratory (Berkeley Labs), can help stop the catastrophic consequences of possible future snow-free timings, what that means for water management. We are analyzing the current investment opportunities that can be made.

Their review paper, “From low to nothingsnow Future and its impact Water resources Published in the Journal “In the Western United States” Nature Review Earth and EnvironmentAnalyzes previous climate forecasts and finds that low to snowless winters occur regularly in the western United States in 35-60 years if greenhouse gas emissions continue in line with high emission scenarios. Did.In addition, the study reassessed long-standing assumptions about water management in the United States and worked with scientists. Water manager We need to work more closely to develop and implement climate adaptation strategies.

The Sierra Nevada, Rocky, Cascade, and other mountains provide tremendous service by capturing, storing, and releasing water for downstream use. Historically, the timing of snowmelt has caused significant delays in water supply from spring to summer, when precipitation is low and water demand is highest for agriculture. The factors that cause the reduction of snow cover are mainly related to the rise in temperature and changes in precipitation characteristics. High temperatures mean that storms increase rainfall and reduce snowfall, limiting the amount of seasonal snow that can accumulate throughout the winter.

Co-led by Berkeley Lab’s Earth & Environmental Sciences Area author Erica Siirila-Woodburn and Alan Rhoades, the study begins with a literature review that extracts hundreds of scientific studies on snow loss.Of them, they identify and analyze 18 studies that had quantitative snow forecasts in the western United States.

When will the future without snow come?

“NS Recent research He emphasized that since the 1950s, snowfall storage on April 1 in the western United States has declined by 21%. This corresponds to the storage capacity of Lake Mead. “Our review found that by the middle of the century we should expect a comparable reduction in snow cover. By the end of the century, the reduction could reach more than 50%. However, the range of uncertainty expands. “

Many water managers use the slightly arbitrary date of April 1 to observe snow cover and make planning decisions. Over the past few decades, there has been a decrease in peak snow cover and an early occurrence of peak snow cover timing, with peaks occurring every 1 degree Celsius (1.8 degrees Fahrenheit) about 8 days before the year.

Many areas have already experienced winters with little snow in recent years, such as the Sierra Nevada Mountains in 2015, when snow levels on April 1 were 5% of normal. This is what the author calls an “extreme” event. This paper defines two other types of low to snowless conditions. “Temporary low to snowless”, or “permanent” when more than half of the mountain basin experiences low to snowless for five consecutive years. From low snow to no snow, this has happened for 10 consecutive years. “Low snow” is defined as when the snow cover (more precisely, the equivalent of snow water, which is a measure of the amount of water released when the snow melts) is below the 30th percentile of the past peak. ..

Using these definitions, California could experience temporary low to snowless in the late 2040s and persistent low to snowless in the 2060s, according to one high-resolution climate forecast. There is sex. In other parts of the western United States, little snow remained in the 2070s. The authors warn of the need for more analysis using a broader set of climate forecasts to increase the reliability of the timeline for the emergence of snow-free to snow-free conditions.

The authors describe climate prediction in their study as follows: “From the middle to the end of the 21st century, the increasing proportion of the western United States is affected by a shortage of snowwater equivalent compared to the historical period, especially only 8-14 2050-2099 78-94. Compared to%, the percentages from 1950 to 2000 are categorized as low to snowless. All regions experience a sharp transition from the mid to late 21st century. “

According to a new Berkeley Lab analysis, if greenhouse gas emissions continue in line with high emission scenarios, the western United States will have regular snow-free winters in 35-60 years. Credits: Jenny Nuss / Berkeley Lab

Impact on water resources

The future impact of low to snowless futures is not limited to streamflow reductions, but it is certainly an important result. For example, in the Sierra Nevada Mountains, the amount of water in a typical April 1 snow cover is: Almost twice the surface reservoir of California..

“The future of less snow and less snow will have a major impact on where and when water is stored in the western United States,” says Siirila-Woodburn. “In addition to the direct impact on recreation, etc., there are many secondary impacts on natural and managed systems from a hydrological point of view. Therefore, groundwater and surface water patterns from increased wildfire outbreaks. Changes and vegetation types and densities. “

Less snow and more rain can affect the groundwater level of mountain systems, as snowmelt penetrates underground more effectively than rainfall. Moreover, Low altitude The overall surface area of ​​the snowmelt stored in the mountains may be reduced, and less snowmelt may penetrate the ground.

Well, good news …

The author’s purpose in conducting this study was to spur thinking about adaptation strategies now. “We want society to be proactive about these changes. Snow pack Rhoades hopes to help understand the problem in a “one-stop shop” way by presenting a bibliographic composition that is non-responsive and has little or no snow. In addition, some new climate adaptation strategies brought about through non-traditional academic and water institutional partnerships that are an important part of the portfolio of adaptation approaches needed to overcome snowfall in warmer worlds. I emphasized. “

One such partnership is a project supported by the Department of Energy. HyperFACETSEleven research institutes are involved, including Berkeley Labs, which works with water business managers in California, Colorado, Florida, and Pennsylvania.

The paper also describes potential adaptation strategies, such as a technique known as controlled aquifer recharge. With this technique, excess surface water is stored underground as groundwater for later use. Another relatively new approach, forecast-based reservoir operations, uses weather and hydrological forecasts to signal decisions regarding the retention or release of water from reservoirs. soon Water storage at Lake Mendocino in California has been shown to increase by 33%.

While these and other technologies show the prospect of increased water supply, the authors also have more mutual cooperation, both between scientists and across society, to expand the portfolio of climate adaptation strategies. Recommended.

“We advocate the best scientific practice involvement and the idea of ​​more cooperation or partnership between researchers and stakeholders. For example, city managers are interested in flood control. , Farmers are interested in water storage and everyone has their own purpose. In science, the field is usually siloed, “said Siirila-Woodburn. “If everyone were working together to manage water, rather than working independently for their own purposes, there would be much more. water Go around ”

Consecutive low snow years will be more common, research projects

For more information:
The future of low to snowless and its impact on water resources in the western United States, Nature Review Earth and Environment, DOI: 10.1038 / s43017-021-00219-y ,

Quote: Management of water resources in the future without snow (October 26, 2021) from https: // October 2021 Obtained on the 26th. .html

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Management of water resources in the future of low to snowless

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