depletion

Global groundwater depletion

March 4, 2024 By EarthWise Leave a Comment

Groundwater is found underground in aquifers and it bubbles up naturally into springs, streams, and rivers. It’s also often pumped out for use by people.

Researchers from UC Santa Barbara have conducted the largest assessment of groundwater levels across the globe, spanning 170,000 wells and nearly 1,700 aquifers across more than 40 countries. The team compiled and analyzed data, including 300 million water level measurements taken over the past 100 years.

In the study, which was recently published in the journal Nature, the researchers found that groundwater is rapidly declining across the globe, often at accelerating rates. In fact, they found that groundwater is dropping in 71% of the aquifers studied. The rates of groundwater decline observed in the 1980s and ’90s sped up from 2000 to the present, highlighting how a bad problem became even worse.

But there are some reasons to be optimistic. That’s because in 16% of the aquifers studied, the researchers found that the rate at which groundwater levels are falling in the 21st century had slowed down compared to the 1980s and ‘90s. The research team highlighted specific success stories in Thailand, Arizona, and New Mexico, where groundwater has begun to recover after interventions to better regulate water use or redirect water to replenish depleted aquifers.

While groundwater depletion isn’t inevitable, the researchers stress that aquifer recovery will require interventions. They hope this study will help scientists, policy makers, and resource managers better understand the global dynamics of groundwater.

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Global groundwater depletion is accelerating, but is not inevitable

Photo, posted October 4, 2016, courtesy of Deborah Lee Soltesz / Coconino National Forest via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Groundwater and climate change

February 22, 2024 By EarthWise Leave a Comment

Groundwater is the vast reserve of water beneath Earth’s surface. It’s an essential resource for humans, plants, animals, and other living organisms. According to the United States Geological Survey, about 30% of all readily available freshwater in the world is groundwater. In areas lacking sufficient surface water supply from rivers and reservoirs, groundwater is critical for meeting the region’s drinking water and food production needs.

But climate change, as well as global population growth, is stressing groundwater resources. As precipitation becomes less reliable due to climate change, surface water bodies can drop too low to provide the needed water. As a result, people turn to groundwater. Depletion of groundwater is already a significant problem, and over-pumping will only increase further as climate change makes traditional sources of water less reliable.

According to a new study led by researchers from the University of Michigan, farmers in India have adapted to warming temperatures by intensifying the withdrawal of groundwater used for irrigation. The study, which was published in the journal Science Advances, found that the rate of groundwater loss could triple by 2080 if this trend continues, further threatening India’s food and water security.

India is the second-largest global producer of common cereal grains such as rice and wheat, and recently passed China as the world’s most populous nation. Without interventions to conserve groundwater, the research team finds that warming temperatures will likely amplify India’s groundwater depletion problem, further threatening the country’s food and water security.

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Groundwater depletion rates in India could triple in coming decades as climate warms, study shows

Where is Earth’s Water?

Photo, posted August 2, 2013, courtesy of Rajarshi MITRA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Airplanes, corn, and groundwater

January 11, 2024 By EarthWise Leave a Comment

The aviation industry wants to slash its greenhouse gas emissions. One proposed strategy is to replace ordinary jet fuel with ethanol. Ethanol in this country mostly comes from corn. The airlines are enthusiastic about the idea; corn farmers are enthusiastic about the idea. Ethanol suppliers are obviously enthusiastic about it. But is it a good idea?

Today, nearly 40% of America’s corn crop is turned into ethanol. Twenty years ago, the figure was around 10%. The massive growth was the result of mandates for ethanol augmentation of gasoline for environmental reasons.

But the environmental benefits of corn ethanol have always been controversial at best when all the energy factors are considered. But apart from that, a very serious issue is that corn is a water-intensive crop, and it can take hundreds of gallons of water to produce a single gallon of ethanol. As the climate warms and corn crops expand, groundwater in many corn-growing areas is being increasingly depleted and groundwater provides half our drinking water and meets far more than just the needs of corn farmers.

Corn farmers and ethanol producers see the rapid growth of electric vehicles as a threat to their lucrative business of supplying the auto fuel industry. The ambitious goals of the airline industry to reduce its emissions would likely require nearly doubling ethanol production.

The situation is a powerful example of the tradeoffs that can arise as the world tries to make the transition away from fossil fuel. Even green solutions can have their own environmental cost and sometimes that cost may be too steep.

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Airlines Race Toward a Future of Powering Their Jets With Corn

Photo, posted September 2, 2007, courtesy of Rosana Prada via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Compost And Landfills | Earth Wise

January 19, 2021 By EarthWise Leave a Comment

Composting is popular as a way to keep solid waste out of landfills and many people turn much of their kitchen waste into rich soil amendments. Cities and towns across the country have composting programs that collect waste from residents to produce large quantities of compost rather than adding the waste to landfills. A new study from North Carolina State University looked into the environmental benefits of actually using compost at landfills.

Most municipal composting programs require that the compost they produce gets used “beneficially”. The new research shows that using compost as an alternative daily cover at landfills is competitive and often superior to the use of compost as a soil amendment in terms of its environmental benefits.

Landfills apply a layer of daily cover to reduce odors, reduce windblown debris, and keep vermin out of landfill waste. Federal regulations require six inches of soil as a daily cover.

Compost from food waste in particular is not always suitable for soil amendment in gardens and agricultural fields because it often contains broken glass and other contaminants.

The North Carolina State study looked at the environmental impact of using compost as daily cover in landfills compared with its use as a soil amendment. They looked at global warming potential, acidification potential, eutrophication (which is the amount of nutrients released to ground and surface water), cumulative energy demand, and the depletion of resources.

The study concluded that using compost as landfill daily cover is environmentally superior with regard to eutrophication, acidification, and global warming potential. On the other hand, soil amendment was better in terms of resource depletion and cumulative energy demand.

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Applying Compost to Landfills Could Have Environmental Benefits

Photo, posted April 22, 2008, courtesy of Alachua County via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.