ShareThisBy CARL T. HALL
Tuesday, November 21, 2006
Coping with climate change takes sophisticated analytical tools. In the mountain environments of the West, it also takes mules, shovels and plenty of sweat.
Noah Molotch, a UCLA research scientist, and Paul Kim, an undergraduate at UC Merced, had no need for their jackets as they broke ground at California's latest global warming research site: a stony Sierra hillside.
They are installing a unique network of ground sensors, weather gear and other equipment to measure how much snow and ice build up each winter in the 400-mile Sierra range _ and then see where the snowmelt goes.
Warming during this century is expected to shrink the snowpack by pushing snow lines to higher elevations. Even if the same amount of precipitation falls, it's expected to come more as rain, less as snow, while spring snowmelts are likely to arrive sooner. That would mean less effective water storage during the long Sierra winters and, possibly, an increased risk of floods from fast mountain runoff.
So tracking Sierra snowfall is hardly an academic exercise.
First step: Dig some holes.
Kim took one shovel, Molotch another. The student struggled against roots and chunks of random granite buried inches beneath the duff. The holes had to be 2 feet deep. Molotch, 33, shared insights gained from his lengthy training for a doctorate in mountain hydrology and climate science.
"Throw a little more arms into it," he suggested.
The new site, called the Sierra Nevada Hydrologic Observatory, is the brainchild of about 20 scientists brought together by a University of California, Merced engineering professor, Roger Bales.
The scientists figure it will take about $2 million a year for 10 years to install the necessary equipment, including devices in trees to monitor sap flow and towers to detect changes in moisture and carbon dioxide in the air.
Some of the first instruments are going in here, an out-of-the-way drainage rarely glimpsed by tourists drawn to the huge trees for which Sequoia National Park is named.
Molotch and Kim were digging holes to contain some of the first soil-moisture and temperature sensors in the network.
"We're certainly entering into some uncharted territory with this," Molotch said. "We want to understand how water moves through the system _ Mother Nature's plumbing _ rather than just treat it as a statistical problem. And to do that, we need data."
If the plans are realized, instrument clusters would extend from the foothills, at 1,200 feet, where most of California's major reservoirs are located, up to the Sierra crest, 11,000 feet or more above sea level.
The scientists hope their electronic networks will produce year-round data in the most vicious High Sierra winters. The goal is to track how water builds up in snow and ice, then gets taken up into trees and plants, soaks into the ground or runs off into streams and reservoirs.
Or, as Bales likes to put it, to "capture the pulse of the Sierra Nevada."
The pulse may be fading. The outlook suggests the state may lose the equivalent of 4 million to 5 million acre-feet of water in a shrinking snowpack this century, about 10 percent of California's total water storage capacity. (An acre-foot is the amount of water it takes to cover 1 acre with water 1 foot deep.)
"We need better information," said Frank Gehrke, chief of snow surveys for the California Department of Water Resources.
Water officials have been tracking Sierra snowfall for decades so that reservoir managers can be told ahead of time how much runoff to expect after storms and during the spring snowmelt. The information guides last-minute management decisions involving the storage and release of millions of gallons of water.
The traditional system, though much improved in recent years, yields estimates that tend to be off by as much as 20 to 30 percent _ a margin of error likely to get wider with each year of increased variability in the weather.
Throughout the West, climate experts say snow-anchored water systems like California's will need to be much more precisely managed to effectively balance such competing interests as urban growth, agriculture, flood control and the needs of wildlife.
(E-mail Carl T. Hall at chall(at)sfchronicle.com)
