‘Without them, groundwater resources become depleted’
Extreme precipitation events that cause severe flooding, loss of life and property damage aren’t exactly at the top of the weather wish list for most people. But it turns out they play a key role in replenishing underground aquifers in the western U.S.
The importance of groundwater will continue to grow in the years ahead — an era of population growth and climate disruption, so understanding the connection between big storms and groundwater recharge is critical, according to U.S. Geological Survey and Bureau of Reclamation scientists who have released a new study analyzing large, multi-year, quasi-decadal groundwater recharge events in the northern Utah portion of the Great Basin from 1960 to 2013.
Some climate models project more rainfall in the West
While most recent research suggests that the Colorado River will be depleted well beyond current demands as global temperatures increase, there may be one small bright spot on the horizon. Even if runoff from snow declines, groundwater replenishment in the basin may hold stead under projected increases in precipitation, the U.S. Geological Survey and U.S. Bureau of Reclamation found in a new study.
“You can’t manage what you don’t measure,” said Fred Tillman, lead author and USGS scientist. “These results are the first step in understanding the quantity of groundwater we can expect in the Upper Colorado River Basin; however, further studies are needed to help more accurately forecast future groundwater availability.”
The Colorado River is a critically important source of water for more than 35 million people in the United States and 3 million people in Mexico. As much as half the water flowing in the rivers and streams in the Upper Colorado River Basin originates as groundwater. Understanding how much groundwater is available and how it’s replenished is important to sustainably manage both groundwater and surface water supplies in the Colorado River basin now and in the future.
In the new study, USGS and Reclamation scientists estimated projected changes in groundwater recharge for the Upper Colorado River Basin from recent historical (1950–2015) through future (2016–2099) time periods using climate projections and a groundwater-recharge model.
Simulated future groundwater recharge through 2099 is generally expected to be somewhat greater than the historical average in most decades due to an anticipated wetter future climate in the basin under the most advanced climate modeling projections. Groundwater resources are replenished through increases in precipitation, which may offset reductions from increased temperatures. The full report is available online in the journal Geophysical Research Letters.
But researchers urged caution interpreting the results because a few of the models suggested decreased future recharge relative to the historical climate period.
New study helps resource managers plan for climate change
Resource managers grappling with the vexing question of how to allocate Colorado River water to the thirsty cities, ranches and farms of the Southwest have some new food for thought. A new U.S. Geological Survey study published this week in the journal Water Resources Research shows that more than half the streamflow in Upper Colorado River Basin originates as groundwater.
‘The Central Valley has many areas where recent groundwater levels are more than 100 feet below previous historical low …’
Farmers in California’s Central Valley pumped more groundwater than ever during the state’s ongoing drought, causing aquifers to drop to new record low levels, according to the U.S. Geological Survey.
The agency recently launched a website to help track Central Valley groundwater depletion and land subsidence. A new paper released about the same time shows geographical nuances in the decline. The biggest changes are in the southern Central Valley, where farmers have shifted from planting annual and seasonal crops to perennial plants. Continue reading “Feds track record Central Valley groundwater depletion”→
FRISCO — According to scientists, arsenic in groundwater continues to be a major public health threat across the U.S. As many as 8 million people may be at risk of exposure to the toxic substance, mainly because of the lack of any regulations, homeowner inaction and inadequate mitigation measures.
A new report focusing on arsenic contamination wells also helps explain the geologic mechanisms causing arsenic contamination and come as other studies show that even low doses of arsenic may reduce IQ in children, in addition to well documented risks of heart disease, cancer and reduced lung function. The reports comprise a special section in the journal Science of the Total Environment. Continue reading “Environment: Report spotlights arsenic pollution”→
Rise in groundwater temps reflects surface temperature record
FRISCO — Decades of detailed temperature measurements from around the globe show how the thickening blanket of heat-trapping greenhouse gas pollutants is steadily raising surface and water temperatures, but until recently, there hasn’t been a lot of information about ground water. Now, scientists with ETH Zurich say groundwater temperature profiles echo those of the atmosphere, albeit damped and delayed.
For their study, the researchers used uninterrupted long-term temperature measurements of groundwater flows around the cities of Cologne and Karlsruhe, where the operators of the local waterworks have been measuring the temperature of the groundwater for 40 years. Continue reading “Climate: Groundwater temps also going up”→
Iowa stream sampling shows common drugs turning up in well water
FRISCO — Research in a small stream near Des Moines, Iowa shows how pharmaceuticals and other hard-to-remove pollutants from treated municipal wastewater can travel into shallow groundwater following their release to streams.