By Andy Evangelista

As a child, Jessica Oster developed a fascination with caves. Growing up in Kentucky, she often visited the Mammoth Cave, the longest in the world. She enjoyed the eerie silence and marveled at the wondrous natural sculptures. For the curious and science-minded youngster, it was a geological Disneyland.

Now, once a month, the UC Davis geology graduate student explores the caves deep beneath the Sierra. As a climate change and water detective, she looks for clues about rainfall and temperature patterns.

Oster studies stalagmites, crystalline cones that form over thousands of years on cave floors. Serving as a kind of time capsule, caves preserve a record of the environmental events in their surroundings.

"Stalagmites grow from groundwater, and groundwater starts as rain and it trickles down into the cave," Oster said. "And while it's doing this, it's picking up signals related to the weather and climate outside the cave."

Oster is one of hundreds of graduate students, the vital cog of UC research, studying the state's water problems in laboratories, in rivers and on top and beneath mountains.

These graduate students perform some of the dirty but critical work for research projects, said Yoram Cohen, director of the Water Technology Research Center at UCLA.

"They are not only bright and creative, they are driven and committed to helping solve what has become a world crisis," Cohen said.

Clues in the caves

Just several inches of a stalagmite, like the one Oster obtained from Moaning Cavern in the Sierra four years ago, offer a 20,000-year archive of weather and rainfall, including during megadroughts that hit California long ago.

In her laboratory, Oster studies mineral traces captured in the stalagmite, whose growth layers can be read like the rings in a tree trunk. And these rings reveal thousands of years of climate records.

"If what we observe in the past is going to hold true for today, then as the climate warms we could expect it to get drier here," she said.

As Oster's fascination with caves continues, so does her drive to apply prehistoric natural events to the future. Her findings in stalagmites will add information from California to a worldwide database that will help other scientists and policymakers better understand, predict and prepare for global climate change.

Transforming the undrinkable

In the spring, Aihua (Richard) Zhu and seven UCLA graduate students packed up the van and headed for the San Joaquin Valley.

But it wasn't your typical spring break. They got down to business, testing a new mini-mobile-modular (M3) "smart" water desalination and filtration system in remote areas of the San Joaquin Valley where agricultural wastewater is the most brackish around.

UCLA graduate student Alex Bartman helped design the M3 water desalination and filtration system.	Aihua (Richard) Zhu

The M3, developed by UCLA researchers at the Water Technology Research Center, can turn the yucky, salty water into potable water. "It's a harsh environment," said Zhu of their mini water desalination station. "But it's exciting when you're able to turn unusable water into water that you can even drink."

The system employs a process — reverse osmosis desalination — that forces saline or polluted water through the pores of a semi-permeable membrane. Water molecules are pressured to pass through these pores, but salt ions and other impurities cannot, resulting in purified water.

The M3 is capable of generating 8,000 to 9,000 gallons per day from brackish groundwater, said Zhu.

The system also acts as an all-in-one mobile plant that can test almost any water source, said graduate student Alex Bartman, who helped design the monitoring system and data acquisition computer hardware. Also its size and mobility — it indeed fits in the back of a van — make it handy and inexpensive for water testing and desalination.

It also can be easily deployed to various locations to produce fresh water in emergency situations, said Bartman.

Amazing GRACE

J.T. Reager

J.T. Reager, a UC Irvine graduate student in earth systems science, doesn't need hiking boots, nor does he pack a lot of equipment to do his research. He stays mostly in a computer laboratory, but has one of the broadest looks of the water supply in the state or any part of the world.

Reager's "eyes" are a pair of satellites, which fly 130 miles apart while circling the earth once every 90 minutes. The satellites, part of the NASA-sponsored Gravity Recovery and Climate Experiment (GRACE), measure the gravitational field of the Earth and show where water is and where it's going.

"I retrieve data from the satellites and turn them into color maps that tell a story of how water is distributed in selected regions," said Reager.

An advantage of GRACE is its ability to track water storage underground. Without GRACE, it would take an army of people over several months to literally dig up the needed information. Reager, for example, has produced maps and charts showing a not so pretty story — depletion of groundwater in the state's Central Valley.

In the combined Sacramento-San Joaquin drainage basins, where water from snowpack already is diminishing rapidly, it is likely that groundwater pumping for irrigation is causing bigger water losses. Such data may sound an alarm to water managers and policymakers regarding water allocation.

And Reager wants his research — now and in the future — to bridge the information gap between scientists and policymakers. His current project uses GRACE to study the water storage capacity of large river basins in the U.S. and their potential for flooding.

Reager received his bachelor's degree in engineering, his master's in oceanography, and now his studies in earth system science give him not just depth, but also breadth of knowledge in climate change.

He won't always confine himself to the laboratory. Reager hopes to wind up in a place like Washington, D.C., where his scientific expertise and advice will be useful to policymakers — and perhaps make a difference.

Andy Evangelista is research communications coordinator in the UC Office of the President's Integrated Communications group.