reservoirs

California Storms And The Megadrought | Earth Wise

February 22, 2023 By EarthWise Leave a Comment

California experienced its wettest 10-day period in 25 years as a result of a series of storms driven by atmospheric rivers in January. The Rocky Mountains got buried in snow from the same weather pattern. For the drought-stricken West, the storms were good news. But they are not the cure for what’s been ailing the region.

In California, the snowpack in the Sierra Nevada mountains has been greatly enhanced, containing twice as much snow as is considered average for this time of year. Without a doubt, it will reduce the impact of the drought that has plagued the state for 23 years. But one big storm or even a series of them is not enough to undo years of minimal precipitation and rising temperatures. Many of the states’ largest reservoirs remain well below historical averages despite the record-breaking rain. It would take several wet years to really allow the state to recover from the drought.

The snowfall in the Rockies is crucial because it is the source of more than two-thirds of the water in the Colorado River. The Colorado River is the water lifeline for 40 million people from Wyoming to Mexico.

The ongoing shrinking of the Colorado River is a crisis that has created massive problems for the multibillion-dollar agriculture industry and for many large cities, including Denver, Phoenix, Salt Lake City, Las Vegas, and Los Angeles. Two of the nation’s largest reservoirs – Lake Mead and Lake Powell – are filled by the Colorado River. The historic low levels of these reservoirs have threatened the functioning of hydropower facilities that provide electricity to millions of people.

The January storms were good news for the West, but its problems are not over.

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This Winter’s Rain and Snow Won’t be Enough to Pull the West Out of Drought

Photo, posted September 18, 2022, courtesy of Sarah Stierch via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Glacial Loss In The Swiss Alps | Earth Wise

December 14, 2022 By EarthWise Leave a Comment

In 2022, glaciers in the Swiss Alps melted more than in any year on record. This is the latest piece of bad news for the country’s glaciers, which have lost more than half of their volume of ice since the 1930s.

The melting season for Switzerland’s snow and ice typically starts in May and ends in early October. This year’s melting season caused glaciers in the Diablerets mountain group to thin by an average of 13 feet, which is 3 times the amount of thinning observed over the past decade. The Tsanfleuron pass between two of the glaciers is now exposed as bare rock for the first time in several thousand years. Across Switzerland, glaciers lost about 6% of their remaining volume just this year. The previous worst year for glaciers was 2003, when losses were nearly 4%.

There was significant melting this year in part because of the small amount of snowfall over the winter. That snow melted quickly, being sped up by the warming effect of dust from the Sahara Desert falling on the snow. By early summer, there was no longer a protective blanket of snow on the glaciers, exposing them to summer heat.

The loss of glaciers is far more serious than the disappearance of aesthetically pleasing landscape features. Glaciers act as reservoirs of water that persist through the summer months. Melt from glaciers provides water to ecosystems and creates habitats for plants and animals. Cold runoff from glaciers affects downstream water temperatures which have a major impact on insects, fish, and other creatures. Globally, melting glaciers contribute more than 20% of the observed ongoing sea-level rise.

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Rocky Road for Swiss Glaciers

Photo, posted June 22, 2015, courtesy of Dennis Jarvis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Bengal Water Machine | Earth Wise

October 31, 2022 By EarthWise Leave a Comment

Over the past three decades, the owners of 16 million small farms in the Bengal Basin of Bangladesh have been pumping shallow groundwater during dry seasons to irrigate rice paddies. By lowering groundwater levels in this way during the dry season, the ability of leakage from rivers, lakes, and ponds to replenish the groundwater was greatly enhanced. Capturing surface water not only improved the recovery of groundwater levels but only helped to reduce flooding during monsoons.

The net result of this enormous collective groundwater pumping by millions of farmers has been the creation of vast natural reservoirs underground that are comparable to what is contained by many of the world’s largest dams. This system of sustaining irrigation has transformed what was previously a famine-prone country into a food-secure nation.

The details of this remarkable transformation have been laid out in a study by University College London recently published in the journal Science. According to the study, over the course of 30 years, more than 75 cubic kilometers of fresh water was captured by this process, which is equivalent to the combined reservoirs of China’s Three Gorges Dam and the Hoover Dam in the U.S.

The authors of the study described the water cycling process as “The Bengal Water Machine” and argue that it can be a sustainable alternative to conventional approaches to seasonal river flow storage for irrigation, which typically involve dams and reservoirs. Such approaches are difficult to implement in densely populated alluvial plains where sand, silt, and clay are laid down by annual floodwaters.

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Millions of farmers “replumb” world’s largest delta

Photo, posted February 2, 2010, courtesy of Melanie Ko via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Climate Change And The Color Of Lakes | Earth Wise

October 19, 2022 By EarthWise Leave a Comment

**According to a new study recently published in the journal Geophysical Research Letters, blue lakes around the world are at risk of turning green-brown if climate change continues unabated.**

For the study, the research team used over five million satellite images of more than 85,000 lakes and reservoirs around the globe between 2013 and 2020 in order to determine each lake’s most common water color. Since lake color can change seasonally, the researchers assessed the most frequent lake color during those seven years.

Algae and sediments affect the color of lakes. But the study found that precipitation, air temperature, lake depth, and elevation also play major roles in determining a lake’s most common water color.

The research team found that blue lakes account for less than one-third of lakes worldwide. Blue lakes tend to be deeper and are often found in cool, high latitude regions with high precipitation and winter ice cover. Meanwhile, green-brown lakes, which account for 69% of all lakes, are found in drier regions, continental interiors, and along coastlines.

As global temperatures rise, lakes will warm, and warmer water produces more algal blooms. As a result, the researchers expect the changing climate to decrease the percentage of blue lakes, many of which are found in the Rocky Mountains, northeastern Canada, northern Europe and New Zealand.

Water color is a simple but viable way to measure water quality that can be done on a global scale using satellites. This approach provides researchers with a way to study how lakes – even the remote ones – are changing.

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Climate change is making lakes turn green-brown

Photo, posted August 27, 2011, courtesy of Paul Schultz via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Cloud Seeding And The Western Drought | Earth Wise

April 6, 2022 By EarthWise Leave a Comment

The massive megadrought affecting the American West is now considered to be the driest two-decade period in the past 1,200 years. The lengthy drought has led to increased wildfires, reduced agricultural productivity, and reduced electricity generation by hydropower plants. The historically low water levels in the largest two reservoirs in the U.S. – Lake Mead and Lake Powell – has triggered reductions in water allocations to Arizona, Nevada, and Mexico.

Several western states have expanded cloud seeding programs in an attempt to increase precipitation. During the past two years, Idaho, Utah, Colorado, Wyoming, and California have all stepped up their cloud seeding efforts. Outside of the US, the United Arab Emirates and China both have implemented massive cloud seeding programs.

A study by researchers at the University of Colorado and the National Center for Atmospheric Research looked at the ability of cloud seeding to increase snowfall. The study unambiguously demonstrated that cloud seeding can increase snowfall. Just how effective it is in terms of how much additional snow seeding produces is less clear.

Given the dire need for water and the fact that cloud seeding is not especially expensive, governments and other users are not hesitating to make use of it.

Unfortunately, the study shed no light on the efficacy of warm weather seeding to produce rain. There is in fact little evidence that seeding clouds to produce rain accomplishes very much. Once again, the prevailing view is that it is worth trying. There do not appear to be environmental downsides to seeding.

The hope is that cloud seeding may at least restore clouds to the state they had been in before industrial pollution and other human activities affected them.

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Can Cloud Seeding Help Quench the Thirst of the U.S. West?

Photo, posted November 21, 2013, courtesy of Sharon Tate Soberon via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Safely Storing Carbon | Earth Wise

February 28, 2022 By EarthWise Leave a Comment

As carbon dioxide levels continue to increase in the atmosphere and emissions reductions aren’t happening as fast as needed, there is growing interest in carbon capture and storage technologies.

The idea is to capture the CO2 emitted from industrial processes or from the burning of fossil fuels in power generation, and then permanently store it out of harm’s way. There are several different types of sites where the CO2 might be stored. Deep saline aquifers are particularly desirable for the purpose, but depleted hydrocarbon reservoirs are commonplace and relatively simple to use. These are oil and gas wells that have been drained of their resources.

In many cases, CO2 has already been injected into these depleted wells as a means of enhanced oil recovery. Therefore, such wells provide a unique opportunity to study what happens to carbon dioxide when it’s stored in these places.

Researchers from Oxford University recently published a paper in the journal Nature that compared the state of depleted wells with injected carbon dioxide to that of wells without the injected gas. They found that nearly 3/4 of the CO2 was dissolved in the groundwater. Unexpectedly, they also found that 13-19% of the carbon dioxide was converted into methane by methanogenic bacteria. Methane is less soluble, less compressible, and less reactive than carbon dioxide.

Producing methane in these wells is therefore undesirable. Deeper sites that have temperatures too high for the bacteria to thrive are much more suitable. This research is important for identifying future carbon capture and storage sites and for designing long-term monitoring programs that are essential for low-risk, long-term carbon storage.

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Safer carbon capture and storage

Photo, posted November 6, 2015, courtesy of CL Baker via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

SuperHot Rock Geothermal Energy | Earth Wise

December 3, 2021 By EarthWise Leave a Comment

The United States in a world leader in geothermal energy. There are geothermal power plants in 7 states which produce about half a percent of the country’s electricity. Conventional geothermal energy plants take advantage of natural underground sources of heat such as geysers, superheated underground reservoirs, and such. Steam from these sources activates generators that produce electricity. However, there are not many places where these systems can be built.

More recently, there has been growing interest in so-called enhanced geothermal systems (or EGS systems) which generate geothermal electricity without the need for natural convective hydrothermal sources. There are many places where underground heat is available but no existing water taps into it. The idea is to tap into the earth’s deep geothermal resources by fracturing rock and pumping water into it to be heated.

AltaRock Energy, a Seattle-based company that develops EGS technology, has recently announced the results of a comprehensive technical and economic feasibility study demonstrating the potential benefits of an EGS system that could use high-temperature impermeable rock deep below the Newberry Volcano near Bend, Oregon. The so-called SuperHot rock there is in excess of 750 degrees Fahrenheit.

Based on measurements at the site and modeling, the study determined that an EGS system at the site could cut the levelized cost of electricity in half when compared with a conventional EGS resources at 400-500 degrees.

The company expects that the study will pave the way for the development of the first SuperHot Rock geothermal resource in the United States.

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AltaRock clears hurdle in quest for ‘next generation’ geothermal resource

Photo, posted June 26, 2018, courtesy of David Fulmer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Drought And U.S. Hydropower | Earth Wise

November 29, 2021 By EarthWise Leave a Comment

The ongoing severe drought in the western U.S. has led to low water levels in the rivers and reservoirs that feed hydroelectric power systems. The Energy Information Administration is projecting a 13.9% decrease in hydroelectric generation this year compared to 2020.

Water levels in Lake Powell have fallen so low that it may not be possible to operate the power plant at Glen Canyon Dam starting as soon as 2022. California officials took the Edward Hyatt hydroelectric plant offline in August because of low water levels on Lake Oroville. Washington, the state with the most hydroelectric power generation, has seen an 11% drop in electricity generated to date this year as compared to last year. That state is actually doing better than others in the West, such as California, where hydro generation is down 38%.

Hydropower accounts for over 7% of the electricity generated in the United States. Five states – Washington, Idaho, Vermont, Oregon, and South Dakota – generate at least half of their electricity from hydroelectric dams.

The current decrease in hydropower is alarming, but it is not unprecedented. The more significant question is whether the drop in generation this year is a sign that this power source is declining and becoming less reliable. According to some scientists, the West is in a “megadrought” that could last for decades.

The greater concern is whether the bad years are likely to become more common because of climate change. Climate projections agree that temperatures will continue to rise, but what will happen to precipitation levels in specific places is much less certain. That is what will determine what the future holds for hydroelectric power.

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Inside Clean Energy: Drought is Causing U.S. Hydropower to Have a Rough Year. Is This a Sign of a Long-Term Shift?

Photo, posted May 7, 2014, courtesy of Tyler Bell via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Greenhouse Gas Emissions From Water Reservoirs | Earth Wise

July 27, 2021 By EarthWise Leave a Comment

A new study by researchers from Washington State University and the University of Quebec at Montreal looked at greenhouse gas emissions from water reservoirs. It is perhaps surprising to think that water reservoirs are a source of greenhouse gas emissions at all, but that much was already known. The new study found that those emissions are actually around 29% higher than previously thought.

Overall, the researchers found that the world’s water reservoirs annually produce methane, carbon dioxide, and other greenhouse gases at an amount equivalent to 1.07 billion tons of carbon dioxide. That is a small fraction of the 36 billion tons produced by fossil fuels and other industrial sources, but it is by no means a negligible amount. In fact, it is more greenhouse gases than emitted by the entire country of Germany, which is the world’s sixth largest emitter.

Decomposing plant matter near the bottom of reservoirs fuels the production of methane, which is far more potent than carbon dioxide in warming the atmosphere. This methane degassing accounts for about 40% of emissions from reservoirs.

The study is particularly important because it may be possible to reduce methane emissions from reservoirs by selectively only withdrawing water from near the reservoirs’ surface, which tends to be relatively methane-poor compared to greater depths. In a related study, reducing withdrawal depth by 10 feet in a Malaysian reservoir reduced methane degassing emissions by 92%.

Human-generated greenhouse gas emissions come from a surprisingly wide range of sources and it is worthwhile studying as many of them as possible in the hope of finding additional ways to reduce the total.

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