Southern Sierra Critical Zone ObservatoryIntegrating measurements for advances in hydrology & geochemistry

Principal Investigator: Roger. Bales, UC Merced

Research support: National Science Foundation

Research partner: Pacific Southwest Research Station, U.S. Forest Service

Planned investigations– water cycle & response to perturbations– coupled hydrologic & (bio)geochemical

processes/cycles– extreme hydrologic events in hydrologic &

(bio)geochemical cycles– vegetation control over fluxes of water &

nutrients– pathways for transport of water, heat & mass– role of seasonal snowpack in determining

critical zone processes

A research platform for studying Earth surface processes in the “critical zone”, extending from the top of vegetation down through groundwater

J. Park

Background

The rain-snow transition zone is particularly vulnerable to large & rapid changes in climate & landcover. While this zone undergoes rapid seasonal changes, going from snowcover to wet soil to dry soil over a 1-2 month period, climate warming will shift this transition period earlier or eliminate it entirely. The result will be major changes in seasonal-to-interannualcritical zone processes involving water, nutrients and ecosystem response of the largely mixed conifer forest found in the rain-snow transition zone. Forest density & the threat of catastrophic fire in the zone are very high, leading to the further likelihood of changes in longer-term critical zone processes. Steep gradients in precipitation patterns, along both elevation and aspect, plus rapid seasonal changes, make this zone an excellent natural laboratory for studying how critical zone processes respond to perturbations, & particularlyhow the water cycle drives critical zone processes. Also, the characteristic spatial differences along gradients offer the opportunity to substitute space for time.

CZO measurements

meteorology & snowpackstream stage & dischargesoil moisture & temperaturestream condition & physical

habitaterosion & sedimentationgeology, soils & littersnowmelt, rain, stream & soil

chemistryriparian & upland vegetationstream invertebrates, algae &

periphyton

CZO team

Roger Bales, UC MercedBeth Boyer, UC BerkeleyMartha Conklin, UC MercedMike Goulden, UC IrvineJan Hopmans, UC DavisDale Johnson, U NevadaJim Kirchner, UC BerkeleyChristina Tague, UC Santa

BarbaraCarolyn Hunsaker, USFS-

PSW9 graduate studentsField hydrologist/geochemistData managerEducation/communications

scientist

More informationSierra Nevada Research Institute

http://snri.ucmerced.eduCZO home:

http://snri.ucmerced.edu/CZOData:

http://eng.ucmerced.edu/snsjho

soils

groundwater

meteorology

Water balance measurements

streams

snow sediment

remote sensingsnow

October 4, 2007 – Merced Sun-Star UC gets chance at dream team for water study By Dhyana Levey A new $4.6 million grant from the National Science Foundation has given UC Merced engineering professors Roger Bales and Martha Conklin their dream team. They have been working on a project to better understand the flow of water from the snow and soil of the high Sierra and how it relates to climate change. This money allows them to start another phase of the project and add more people to work on it. As the mountain snowpack melts, it sends water into the state's reservoirs, which goes on to irrigate crops and move hydropower production. But climate changes have caused snow to melt at an irregular rate, making the level of water entering reservoirs tough to predict. This research can help clear up some of that uncertainty, Bales said. The professors, who also work with UC Merced's Sierra Nevada Research Institute, began their research last year. They spent most of a previous National Science Foundation $600,000 grant on equipment -- sensors to measure snow depth, soil moisture and the movement of liquid through vegetation. Two weeks ago the National Science Foundation awarded UC Merced $4.6 million to continue the research over a five-year period. While some of this money will go toward more gear, most of it will supply the project with the appropriate people. "We're excited we can get a large team together," Bales said. "This is our first opportunity to start answering questions, to have the ideal team." This group includes Bales and Conklin, three professional researchers, eight graduate students -- two from UC Merced and six from other campuses -- and six more professors. They come from University of California campuses in Berkeley, Irvine, Davis and Santa Barbara, and the University of Nevada, Reno. The team is using a U.S. Forest Service research site, the Kings River Experimental Watershed (KREW) in the southern Sierra, southeast of Shaver Lake. The Forest Service and the California Bay-Delta Program have already made large investments in equipment at that site. Carolyn Hunsaker, a research ecologist with the U.S. Forest Service in Fresno, will continue research there for forest management and said in a statement that she is excited to be hosting this new effort at KREW. The research team is collecting data from elevations ranging from 5,000 to 7,000 feet into the Sierra -- areas most affected by climate change, Bales said. They are studying what he referred to as the "Critical Zone," the region from the top of the trees down through the groundwater. A soil sensor dug into the ground determines the amount of moisture there with electric currents. The sensor gives off a different voltage depending on the amount of water. The snow sensor sits on a pole and sends an acoustic signal down to the ground. The measurement of snow on the ground is determined by how long it takes for the signal to bounce back up. Trees also pump water into the air. "It comes up through the roots, trunk, needles and into the atmosphere," Bales explained. To gauge how much water trees or other vegetation are putting off, the team uses a tower to measure moisture above them, as well as long needles that measure temperature and "sap flow," the movement of liquid through the trunk. "With climate change, if snow melts early, the soil dries out earlier," he said. "There is less water for vegetation, and trees stop growing." The purpose is to forge a better understanding of how the ecosystem responds to changes in the snowpack and rainfall pattern. In turn, that understanding can lead to better predictions on how water will flow and how vegetation will be affected. Water managers can then forecast how much water from melted snow will flow into state reservoirs, to better determine how much should be released from reservoirs in the short and long term. Another important phase of the project is education, which the new grant also funds, Conklin said. The team will work with the Yosemite Institute, which brings about 13,000 sixth-to 12th-grade students to Yosemite once a year to learn about the area. Institute instructors will be trained by the team to teach their students about hydrology, biogeochemistry and geology. "The Sierra Nevada provides about 40 percent of California's water -- it's an important resource," she said. "As we manage the system, we are better off with informed citizens."

### Shorter articles appeared Oct 3 in the San Jose Mercury News, San Francisco Chronicle, San Francisco Examiner, News 10 Sacramento, Fresno Bee, Modesto Bee, Merced Sun-Star, San Diego Union-Tribune, KESQ Palm Springs, KSBY San Luis Obispo, KTVN Reno