Snow melt from the snow pack in the Sierra Nevada mountain range provides drinking water to about 30% of California’s residents, irrigates key crops in the San Joaquin valley, and runs hydroelectric power plants that supply at least 15% of the state’s electricity. Scientists Martha Conklin and Tom Harmon of the University of California, Merced are conducting research at the Southern Sierra Critical Zone Observatory, using wireless sensor technology to more accurately measure snow pack and snow melt so that state water managers can make better decisions on how to allocate this precious resource. "Sustainability: Water" is produced in partnership with the National Science Foundation.
Sustainability - Water – Sierra Nevada Snow Pack & Snow Melt
ANNE THOMPSON, reporting:
With its rugged, snowcapped mountains, clear freshwater lakes, and massive sequoia trees, the Sierra Nevada mountain range in California is one of the most visually stunning landscapes in the United States.
In addition to its beauty, snow pack and snow melt from this 400-mile stretch of mountains serves a purpose: providing drinking water to about thirty percent of the residents in California, irrigation water to the more than $35 billion a year agricultural industry in the San Joaquin Valley, and water to run the hydroelectric power industry that supplies at least 15% of the state’s electricity.
MARTHA CONKLIN, (University of California, Merced): In California, we wait with bated breath to hear about the size of the snowpack. In recent years, our precipitation patterns have been changing with maybe less precipitation during the wintertime and a little more precipitation in the springtime.
THOMPSON: Martha Conklin is a hydrologist at the University of California-Merced and is supported in part by the National Science Foundation. She belongs to a team of scientists that study the Sierra Nevada snowpack to make more precise measurements and predictions of snowmelt and runoff, so the water can be better managed.
CONKLIN: We'll come up with information systems that are going to be useful for better water resources decisions. We actually provide knowledge to the state of California on how it's going to meet the changing snowpack and how to adapt our water management systems to do that.
THOMPSON: Following the Earth's water cycle, water precipitates as snow over the higher elevations of the Sierra Nevada from November to April, accumulating into a thick snowpack.
CONKLIN: That basically provides free water storage for us for six months of the year because that water that falls as solid precipitation just sits up there.
THOMPSON: The snowpack remains intact until the weather warms during the spring and summer months and generates snowmelt. The water then moves slowly downhill before it ends up in streams and rivers as runoff, or percolates into the soil as groundwater. But warming temperatures in a changing climate cause more water to precipitate as rain rather than snow. This rain never accumulates as snowpack. Instead, runoff occurs earlier, potentially leading to water shortages later in the year. Tom Harmon is an environmental engineer and lead scientist for the water sustainability project at UC Merced.
TOM HARMON (University of California, Merced): We've relied a lot on past history to try to judge how much water we'll have and statistically that used to work out. But now the climate change is changing those statistics and we can't use the past as a very good predictor anymore.
THOMPSON: Harmon, Conklin and other scientists are conducting research at the Southern Sierra Critical Zone Observatory, or CZO, located near Shaver Lake, California. The data from this observatory is used to understand snowpack accumulation, its water content, and melt rate. The information is then used by many water management groups throughout California to help better manage dams and water release schedules.
HARMON: I think now the next challenge is how to put together that data carefully, accurately and connect it with a theory that makes sense and covers all the processes in sufficient detail; that we gain predictive capabilities.
THOMPSON: To more accurately measure snowpack, the Southern Sierra CZO has developed a system of wireless sensors strategically clustered around several watershed locations that collect data in real time.
MATT MEADOWS, (University of California, Merced): We're measuring precipitation, distribution of precipitation in the snow pack, and how that snow melts and goes into the soil, what our soil water content is, and how the water actually moves from the soil into the stream.
THOMPSON: In addition, a network of flux towers that soar to more than 150 feet high, measure fluctuations in the atmosphere that quantify the net rate of water exchange during evapotranspiration, or the water from snowpack, vegetation, and the soil, that moves to the air thus removing water from the critical zone.
By collecting this data, scientists can provide information that can help determine not only how much water will be available, but when and where it will be available.
CONKLIN: We look at what we can do with developing better information about the snowpack, is to provide information to decision-makers that they can make better decisions and they know how much water is available in the system.
THOMPSON: Knowing where the snow is and how much runoff and river flow to expect in a given season can provide the information necessary to help water managers allocate water resources for people, agricultural, environmental, and industrial needs.
