reservoirs

Lakes Are Shrinking | Earth Wise

September 11, 2023 By EarthWise Leave a Comment

A study by the University of Colorado Boulder has found that more than half of the world’s largest lakes have shrunk over the last three decades. This is a very big problem because about one-quarter of the Earth’s population lives in the basin of a drying lake. People depend on lakes for drinking water and irrigation and lakes are central to the survival of local ecosystems as well as migrating birds. Lakes cover only about 3% of the planet, but they hold nearly 90% of the liquid surface freshwater.

The study used satellite observations from 1992 to 2020 to estimate the area and water levels of nearly 2,000 freshwater bodies. These account for 96% of Earth’s total natural lake storage and 83% of that in man-made reservoirs. About 53% of the world’s lakes have clearly shrunk, while only 22% have gained water. The study estimates that about 160 trillion gallons of water has been lost over the 28-year period. That’s about 17 times the maximum capacity of Lake Mead, the largest reservoir in the United States.

Many of the world’s most significant lakes have been shrinking. The dramatic declines in Lake Mead have been headline news for years. The Caspian Sea, which is the world’s largest inland body of water – has long been declining.

The main causes of the decline in natural lakes are climate change and human consumption. Reservoirs face an additional major problem of sediment buildup which reduces their storage capacity and diminishes their benefits of water supply, flood control, and hydropower.

Lake loss is a big problem.

**********

Web Links

More than half of the world’s largest lakes are drying up

Photo, posted April 10, 2018, courtesy of Ninara via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Plastic In Lakes | Earth Wise

August 28, 2023 By EarthWise Leave a Comment

We are always talking about the millions of tons of waste plastic that finds its way into the oceans and about the challenges of trying to remove it. A new multinational study has found that the concentration of plastics and microplastics in some lakes is even worse than in the so-called garbage patches in the oceans and some of these lakes are even in remote places around the world

Scientists from institutes in multiple countries collected water samples from 38 lakes and reservoirs in 23 countries across six continents. The samples were then all analyzed by the University of Milan to assess the presence of plastic particles more than a quarter millimeter in size.

The study found that two types of lakes are particularly vulnerable to plastic contamination: lakes and reservoirs in densely populated and urbanized areas and large lakes with elevated deposition areas, long water-retention times, and high levels of human influence.

Lakes found to have the highest concentration of plastic included some of the main sources of drinking water for communities and were also important to local economies. These included Lough Neagh in Northern Ireland, Lake Maggiore in Italy, and Lake Tahoe on the California/Nevada border. Not all the lakes studied contained large amounts of plastic. For example, Windermere, the largest lake in England, had very low concentrations of plastic in surface water.

This was the first global survey of the abundance and type of plastic pollution in lakes and reservoirs and the scale of freshwater plastic pollution is sobering indeed. There is widespread concern that plastic debris is having harmful effects on aquatic species and ecosystem function and clearly is not limited to marine ecosystems.

**********

Web Links

Plastic pollution is higher in some lakes than oceans

Photo, posted May 27, 2019, courtesy of Jonathan Cook-Fisher via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Solar Panels On Canals | Earth Wise

August 25, 2023 By EarthWise Leave a Comment

There has been growing interest in installing solar panels on top of reservoirs to make use of the available space to make electricity and reduce evaporation. There has been far less interest in installing solar on canals and aqueducts. But that is changing and a new project in California is part of that change.

A study by the University of California, Merced estimates that 63 billion gallons of water would be saved by covering California’s 4,000 miles of canals with solar panels. All that installed solar would generate a significant amount of electricity.

The idea is going to be tested in the Turlock Irrigation District in Central California with Project Nexus, which is the installation of solar panels over 1.8 miles of canals that are between 20 and 110 feet wide. The panels will sit between 5 and 15 feet off the ground. UC Merced researchers will study impacts ranging from evaporation to water quality and use the results to make recommendations with respect to wider use of the technology.

California isn’t the first place to put solar on a canal. India pioneered it on one of the largest irrigation projects in the world. The Sardar Sarovar dam and canal project brings water to hundreds of thousands of villages in the dry, arid region of India’s Gujarat State.

Meanwhile, the Gila River Indian Community in Arizona received funding from the Bipartisan Infrastructure Law to install solar panels on their canals in an effort to save water and reduce stress on the struggling Colorado River.

The world of water infrastructure does not embrace change easily but covering canals with solar panels is an idea whose time may have come.

**********

Web Links

Solar panels on water canals seem like a no-brainer. So why aren’t they widespread?

Photo, posted December 11, 2005, courtesy of Dave Parker via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Floating Solar And Hydropower | Earth Wise

August 16, 2023 By EarthWise Leave a Comment

Installing solar panels on the surface of reservoirs is an up-and-coming trend. The arrays of solar panels produce renewable energy while at the same time shielding significant expanses of water from the sun’s heat, thereby reducing evaporation. The panels also help to inhibit the growth of algae.

Two recent floating solar installations are demonstrating the synergy between solar power and hydroelectric power.

The Lazer floating solar plant in France comprises over 50,000 solar panels and is capable of producing 30 MW of power. The reservoir serves a 16.5 MW hydropower plant. During the summer, the water from Lazer Reservoir is used primarily for crop irrigation and the solar plant supplements power generation as the reservoir water level experiences variations. This is the first facility of its kind to be installed in France. The company that built it – the EDF Group – had already built four floating solar power plants in Israel and the US.

In Colombia, the Aquasol solar project is installed at the 340 MW Urrá hydropower plant. Its 2,800 solar panels produce enough power to offset the amount of energy it takes to operate the dam. The floating solar system is designed to withstand water-level fluctuations of up to 120 feet.

Floating solar systems can help keep power flowing when low water levels or other adverse conditions reduce hydroelectric output. About 60% of the world’s renewable energy comes from hydropower. Given this fact, there are countless opportunities to deploy floating solar that maximizes zero-emission energy generation as well as diversifying clean energy sources.

**********

Web Links

Floating solar and hydropower: A match made in renewable energy heaven

Photo, posted October 25, 2010, courtesy of Martin Abegglen via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Large Lakes In Decline | Earth Wise

June 27, 2023 By EarthWise Leave a Comment

Globally, freshwater lakes and reservoirs hold 87% of the planet’s liquid freshwater, making them a valuable resource for both people and wildlife. Despite their value, the long-term trends and changes to water levels of lakes have been largely unknown – until now.

According to a new assessment recently published in the journal Science, more than half of the largest lakes around the world are losing water. Using satellite observations and climate data, the research team created a technique to measure changes in water levels in nearly 2,000 of the world’s biggest lakes and reservoirs, representing 95% of the total lake water storage on Earth.

The results are staggering. According to the findings, 53% of Earth’s largest lakes and reservoirs now store significantly less water than they did in 1992. The total amount of water lost is estimated to be 144.5 cubic miles, which is equivalent to the volume of 17 Lake Meads (the largest reservoir in the U.S.).

Unsurprisingly, climate warming and human consumption were the main drivers of water loss from lakes, whereas sedimentation — the buildup of debris — was the biggest driver of water loss in reservoirs. Roughly one-quarter of the world’s population – two billion people – live in the basin of a drying lake, indicating the urgent need for sustainable water resources management.

But the news is not entirely bleak. According to the research team, the new method of tracking lake water storage trends can give water managers and communities insight into how to better protect this critical resource.

**********

Web Links

Satellites reveal widespread decline in global lake water storage

Photo, posted February 10, 2010, courtesy of Ninara via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Geothermal Energy Storage | Earth Wise

May 22, 2023 By EarthWise Leave a Comment

About 12% of the energy consumed by humanity is used to heat and cool homes and businesses. A study by researchers at Lawrence Berkeley National Laboratory and Princeton University looked at a novel approach to making use of underground water to maintain comfortable temperatures and reduce consumption of natural gas and electricity.

The idea is to use aquifer thermal energy storage (known as ATES) to provide both heat in the winter and cooling in the summer. The concept leverages the heat-absorbing property of water and natural geological features. The idea is to pump up water from existing underground reservoirs and heat it at the surface using environmental heat or even excess energy from solar or wind generation. Then the warm water is pumped back down. It stays warm for a long time – even months – because the earth is a good insulator. When the water is pumped back up in the winter, it is much hotter than the ambient air and can be used to supply heat to buildings.

Alternately, water can be pumped up and cooled in the winter and then put back down underground and stored until cooling is needed in the summer months.

This technology has not been used much in the US, but it is gaining recognition internationally, particularly in the Netherlands. It can perform very well in areas with large seasonal fluctuations.

The research study used modeling and various simulations to estimate how much energy ATES could save on the US grid. The results showed that adding ATES to the grid could reduce consumption of petroleum products for heating and cooling by up to 40%. The system could also help prevent blackouts by reducing high power demand during extreme weather events.

**********

Web Links

Underground Water Could be the Solution to Green Heating and Cooling

Photo, posted February 19, 2012, courtesy of Sanjay via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Two Lost Lakes Return To California | Earth Wise

May 10, 2023 By EarthWise Leave a Comment

The recent siege of powerful storms in California driven by a series of atmospheric rivers has had a significant effect on the severe drought that has plagued most of the state for many years. Many of the state’s reservoirs are at the highest level they have been for decades. The snowpack in the Sierras is well over 200% of its historical average. Many parts of the state are no longer considered to be in drought conditions, and, in fact, flooding has been a serious problem in some areas. This flooding has had some surprising results.

Two California lakes that drained a century ago have reappeared as a result of floodwaters from the recent storms.

Tulare Lake, in California’s Central Valley used to be fed by rain and snowmelt from the Sierras. A system of dams and canals constructed in the early 20th century to support regional agriculture diverted water away from the lake. It used to be the largest freshwater lake in the West but farmers ultimate planted crops in the dried lakebed.

The atmospheric river events in March inundated that farmland and once again there is water in Tulare Lake.

Owens Lake, on the eastern side of the Sierra Nevada, was long fed by mountain streams. The 1913 construction of the Los Angeles Aqueduct redirected water to that city and desiccated the lake. Floodwaters in March caused a partial collapse of the aqueduct and when the spill gates on the aqueduct were opened to drain the damaged areas, floodwaters poured in and partially refilled the lake.

California has suffered from drought for many years. With its massive snowpack, as the weather warms, the state may face even more flooding.

**********

Web Links

Two Long-Drained California Lakes Refilled by Floodwaters, Satellite Images Show

Photo, posted November 10, 2014, courtesy of CN via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

California: Drought Or No Drought? | Earth Wise

April 26, 2023 By EarthWise Leave a Comment

Just a few months ago, millions of people in California were living under challenging water conservation rules. The past three years were the driest on record and reservoirs were depleted, landscapes dried up, and the snowpack in the Sierras at very low levels.

But in recent months, a dozen atmospheric river storms have brought huge amounts of rain and snow to the state. Twelve out of 17 major reservoirs in the state have been replenished, the snowpack is over 240% of normal, and brown hills are blooming once again.

So, is the California drought over? According to the experts, the answer is: sort of.

The record snowpack and heavy rains have erased the most severe aspects of the drought in many parts of the state. Only 9% of the state is now experiencing “severe” or “exceptional” drought, down from 55% last fall.

But the changes are basically all at the surface. Groundwater in the state is still extremely low and the state’s cities and farms are still using more of it than is appropriate. The state has been unwisely overusing its groundwater aquifers because of the drought and this one year of heavy rains cannot replenish levels that have been dropping for years.

California has been rolling back many of the most severe drought restrictions that had been imposed but has not entirely lifted the drought emergency status. Meanwhile, the massive snowpack in the mountains will begin to melt as the weather warms and, in many areas, Californians will face flooding. Water is a complicated business in California.

**********

Web Links

Drought or no drought? California left pondering after record winter deluge

Photo, posted August 28, 2019, courtesy of Joyce Cory via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

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.

**********

Web Links

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.

**********

Web Links

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.

**********

Web Links

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.

**********

Web Links

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.

**********

Web Links

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.

**********

Web Links

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.

**********

Web Links

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.

**********

Web Links

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.

**********