Earth’s Underground Water Quantified
Jonathan Amos | BBC Science Correspondent
The total amount of groundwater on the planet, held in rock and soil below our feet, is estimated to be 23 million cubic km.
If this volume is hard to visualise, imagine the Earth’s entire land surface covered in a layer some 180m deep.
The new calculation comes from a Canadian-led team and is published in the journal Nature Geoscience.
Significantly, little of this water — just 6% — is the kind of bankable resource that is most useful to people.
That small fraction is referred to as “modern” groundwater: it is extractable because it is near the surface, and can be used to supplement above-ground resources in rivers and lakes.
“It’s the groundwater that is the most quickly renewed – on the scale of human lifetimes,” explained study leader Tom Gleeson from the University of Victoria.
“And yet this modern groundwater is also the most sensitive to climate change and to human contamination. So, it’s a vital resource that we need to manage better.”
Groundwater Pumping Controls Elusive
Emery Cowan | Arizona Daily Star
The piles on Nancy Waldrop’s dining room table just keep growing — newspaper clippings, pictures, handwritten letters and maps, all arranged into separate stacks. Waldrop has been collecting the papers since the spring of 2014, when the well that supplies water to her Parks home went dry.
She believes the cause is the Parks Water Hole, a commercial standpipe just to the west of her property where local residents fill their water tanks.
Jim Dewar, who oversees Parks Water Hole, has a different perspective. Dewar maintains it was the third year of severe drought, not any connection between the wells, that caused Waldrop’s well to go dry because the water flow into his well has been normal since last October. Waldrop’s well, however, is still dry.
Coconino County should never have permitted the water standpipe, considering the potential for drawdown, said Waldrop, who has spent months lodging complaints with federal, state and local agencies. On Monday, she delivered a handwritten letter to the county urging denial of the standpipe’s conditional use permits, which are up for renewal.
My Turn: Earthquakes threaten Arizona (and That’s Not All)
Lee Allison, AZ I See It | Arizona Republic
Arizona can (and has) fallen victim to plenty of geologic hazards. Here’s how we’re trying to stop them from causing major damage.
Arizona is subject to a wide array of geologic hazards.
That includes flooding, debris flows or mudslides, landslides, gradual land sinking (called subsidence) and earth fissures, swelling and collapsing soils, sinkholes and — yes — earthquakes.
Menace 1: Earthquakes
On Nov. 1, three earthquakes near Black Canyon City with magnitudes of 3.2, 4.0, and 4.1 rattled central Arizona — home to more than 4.5 million people, or roughly three-quarters of the state’s population.
Because Arizona has far fewer earthquakes than California, there is a widespread sense that they are not a problem here. Yet, in 2014, hundreds of earthquakes were detected in Arizona. Most were too small to be felt or occurred in remote areas. The largest events of the year were a magnitude 5.3 earthquake near Duncan in far southeastern Arizona and a magnitude 4.7 quake in Oak Creek Canyon between Sedona and Flagstaff.