For example, in places where annual rainfall may increase by 20 percent as a result of climate change, the groundwater might increase as much as 40 percent.
Conversely, the analysis showed in some cases just a 20 percent decrease in rainfall could lead to a 70 percent decrease in the recharging of local aquifers — a potentially devastating blow in semi-arid and arid regions.
But the exact effects depend on a complex mix of factors, the study found — including soil type, vegetation, and the exact timing and duration of rainfall events — so detailed studies will be required for each local region in order to predict the possible range of outcomes.
The research was conducted by Gene-Hua Crystal Ng, now a postdoctoral researcher in MIT's Department of Civil and Environmental Engineering (CEE), along with King Bhumipol Professor Dennis McLaughlin and Bacardi Stockholm Water Foundations Professor Dara Entekhabi, both of CEE, and Bridget Scanlon, a senior researcher at the University of Texas. The results are being presented Wednesday, Dec. 17, at the American Geophysical Union's fall meeting in San Francisco.
The analysis combines computer modeling and natural chloride tracer data to determine how precipitation, soil properties, and vegetation affect the transport of water from the surface to the aquifers below. This analysis focused on a specific semi-arid region near Lubbock, Texas, in the southern High Plains.
Predictions of the kinds and magnitudes of precipitation changes that may occur as the planet warms are included in the reports by the Intergovernmental Panel on Climate Change (IPCC), and are expressed as ranges of possible outcomes. "Because there is so much uncertainty, we wanted to be able to bracket" the expected impact on water supplies under the diverse climate projections, Ng says.
"What we found was very interesting," Ng says. "It looks like the changes in recharge could be even greater than the changes in climate. For a given percentage change in precipitation, we're getting even greater changes in recharge rates."
Among the most important factors, the team found, is the timing and duration of the precipitation. For example, it makes a big difference whether it comes in a few large rainstorms or many smaller ones, and whether most of the rainfall occurs in winter or summer. "Changes in precipitation are often reported as annual changes, but what affects recharge is when the precipitation happens, and how it compares to the growing season," she says.
The team presented the results as a range of probabilities, quantifying as much as possible "what we do and don't know" about the future climate and land-surface conditions, Ng says. "For each prediction of climate change, we get a distribution of possible recharge values."
If most of the rain falls while plants are growing, much of the water may be absorbed by the vegetation and released back into the atmosphere through transpiration, so very little percolates down to the aquifer. Similarly, it makes a big difference whether an overall increase in rainfall comes in the form of harder rainfalls, or more frequent small rainfalls. More frequent small rainstorms may be mostly soaked up by plants, whereas a few more intense events may be more likely to saturate the soil and increase the recharging effect.
"It's tempting to say that a doubling of the precipitation will lead to a doubling of the recharge rate," Ng says, "but when you look at how it's going to impact a given area, it gets more and more complicated. The results were startling."
Elizabeth Thomson | EurekAlert!
Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter
17.08.2017 | Swansea University
Climate change: In their old age, trees still accumulate large quantities of carbon
17.08.2017 | Universität Hamburg
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
21.08.2017 | Materials Sciences
21.08.2017 | Health and Medicine
21.08.2017 | Materials Sciences