Mines-led study yields insight on age of groundwater across the U.S.

GOLDEN, Colo., March 11, 2016 – Have you wondered how long it takes for rain or snow to move into a river or stream? A Colorado School of Mines-led study recently published in the journal Geophysical Research Letters, helps inform scientists’ understanding of timing and persistence water over the major basins of North America.

Mines researchers, along with colleagues from Syracuse University, Stanford, Oregon State and Bonn University, used computer models to predict and understand the residence times of groundwater over the major basins including the Mississippi and Colorado rivers. They found that water in streams can anywhere from days to thousands of years old.

“Results of the modeling showed that the geology of the subsurface controlled the peak time for water to make it’s journey while aridity controlled the spread of ages,” said Reed Maxwell, professor of hydrology and director of the Integrated Groundwater Modeling Center at Mines. “This helps us better understand timing and persistence of things like contaminant transport, but also how plants have nutrients to grown, how clean the water is, and even things like how rock weathers to become soil over scales we have never been able to tackle before.” 

Reed noted the time elapsed between a precipitation event or snowmelt and water’s arrival in a river governs flow and storage, while also moderating water for human use and ecosystem function. Previous work has shown that water may take from months to thousands of years to make this journey — yet these so-called residence times are difficult to directly observe and have to be inferred from radioactive bomb-fallout or carefully measured in small research watersheds.

These findings can guide where and how we observe our earth and highlight the need for future modeling studies and stream contribution observations to explore relationships between water age, soil and rock type and aridity.

Learn more about the study online.



Karen Gilbert, Director of Public Relations, Colorado School of Mines | 303-273-3541 | kgilbert@mines.edu
Kathleen Morton, Digital Media and Communications Manager, Colorado School of Mines | 303-273-3088 | kmorton@mines.edu


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Colorado School of Mines is a public research university focused on science and engineering, where students and faculty together address the great challenges society faces today - particularly those related to the Earth, energy and the environment.