Video feature from April-June 2009
More about climate change:
“Tracking Raindrops”
Scientists at UC Berkeley’s Hydrowatch Project are leading a 4-year effort to monitor and measure water and its pathways in two watersheds, one in Coastal Mendocino County and one in the mountains north of Lake Tahoe. Studies will help researchers to predict the impact of climate change on our fresh water supplies
UCB atmospheric scientist Inez Fung, project leader, says, "I asked what I thought was a very simple question: How old is the water in the stream? Is it from yesterday's rain, is it from last year's rain or this season's rain, or is it a hundred, thousand years old?"
Fung and colleagues, including UCB plant biologist Todd Dawson, are looking at isotopes of oxygen in water samples — an ingenious way to help trace the source of water in a stream, the soil, and the trees. Isotopes of an element have variable numbers of neutrons in their nuclei and so different atomic weights. Each water source has an isotopic "fingerprint,” which can be used to identify and quantify how that source contributes to watershed processes.
Dawson notes, "As water undergoes evaporation, condensation or freezing into snow or ice, it changes its isotope values. Scientists can actually learn if it came from a cold storm or a warm storm, whether it came from snow, or fog. Scientists can trace these unique fingerprints as the water moves through different watersheds."
Knowing where the water comes from and how fast it’s moving through a watershed enables the investigators to create computer simulations of different water scenarios.With these, they can predict how climate change might affect our fresh water supplies.
“We are predicting [[that]] where it is warm or hot, it's going be hotter and drier,” says Fung. “That means less water available to the plants. And if the plants are not there, then we have less transpiration, less communication of water from the soil to the atmosphere, and we're in for a drought. And that's what we're predicting.”
Studies are ongoing at UC Natural Reserve System sites, and the accompanying video is a joint project of UC and KQED Television.
