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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

Oil Drilling In Los Angeles | Earth Wise      

February 24, 2022 By EarthWise Leave a Comment

Los Angeles may close its oil drilling chapter

Movies were not the first industry to boom in Los Angeles.  Oil was.  There was a lot of it, and it flowed close to the surface triggering rampant drilling all over the area.  By the 1920s, Los Angeles was one of the largest oil-exporting regions in the world.

A century later, there are over 20,000 active, idle, or abandoned wells spread across LA county, home to 10 million people.  Some are hidden behind facades; others are plainly visible, pumping away day and night.  About a third of Angelenos live less than a mile from an active well site.  In the last 20 years, improved oil extraction technology has actually led to a resurgence of oil drilling in Los Angeles.

Studies of the health impact of LA’s oil wells found that asthma is significantly more common among people living near oil wells than elsewhere in the county.  Surveys of residents’ lung functions revealed lower function on average when people live near wells.   Measurements of toxins in the air – such as benzene, toluene, and n-hexane – showed that levels of these substances were significantly reduced when oil production at a site stopped.

This issue has finally come to the forefront after a nearly a decade of community organizing and studies of adverse health effects.  In a unanimous vote on January 26, the Los Angeles City Council took the first step toward phasing out all oil and gas extraction in the city by declaring oil extraction a nonconforming land use.  The LA County Board of Supervisors voted unanimously to phase out oil extraction in unincorporated county areas.  Los Angeles’ long, troubled history with urban oil drilling appears to be nearing an end.

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Los Angeles’ long, troubled history with urban oil drilling is nearing an end after years of health concerns

Photo, posted March 26, 2016, courtesy of Giuseppe Milo via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Global Assessment Of Groundwater Wells | Earth Wise

May 19, 2021 By EarthWise Leave a Comment

Groundwater wells are at risk

Water is a fundamental need for every human being on the planet.  Each person requires more than five gallons of clean and safe water a day for drinking, cooking, and keeping clean.

Groundwater wells remain one of the primary sources of drinking water.  In fact, more than half of the world’s population gets its drinking water from groundwater wells.  Groundwater wells also sustain more than 40% of irrigated agriculture.

Researchers from UC Santa Barbara have recently compiled the most comprehensive assessment of groundwater wells to date.  Their research, which was recently published in the journal Science, spanned 40 countries, which collectively account for more than 50% of all groundwater pumping. 

According to the survey’s findings, many wells are at risk of running dry – up to one in five wells, to be exact.  The researchers compared the depths of water tables against well depths. They found that 6% to 20% of the wells in the study were at risk of running dry if water levels continue to decline by just a few meters.

In many areas where groundwater levels are declining, the research team found that new wells are not being drilled deeper to keep pace with the falling water table. As a result, newer wells are just as vulnerable as older wells should groundwater levels continue to decline.  

The researchers hope to expand on this study to include data from China, Iran, and Pakistan, three major users of groundwater from which the researchers could not obtain records.  The researchers also plan to investigate how quickly water tables are dropping and where the trend is accelerating.   

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The largest assessment of global groundwater wells finds many are at risk of drying up

Photo, posted January 20, 2018, courtesy of François Molle via Water Alternatives Photos on Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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