Rina Schumer and Hal Klieforth

LTkcschumer0032Scientists collaborate to find new use for vast data collection

After every storm and during every winter from 1965 to the 1996, Desert Research Institute (DRI) scientist Harold Klieforth collected snowpack samples at different sites scattered throughout the Tahoe Basin. In collecting this regional weather data, Klieforth established a network of precipitation monitoring bases that covers 1,000 square miles of the Truckee River watershed, which includes Lake Tahoe. His work for the Bureau of Reclamation’s cloud seeding project resulted in the most comprehensive collection of precipitation data for the Tahoe Basin.

“To my knowledge, these records are unique,” he said. “I believe that no other such series of measurements and observations have been made after every storm during such a long period over such a large region of mountainous terrain.”

Now 30 years after he began collecting data, DRI scientist Rina Schumer is using the data to validate climate models that predict freezing levels and snowpack. Schumer first became interested in Klieforth’s vast data collection while reading the many studies on the impact of changing Sierra snowpack on California water supply.

“The hydrology of the western and eastern Sierra Nevada are very different because the mountain range causes a rain shadow.” Schumer says, adding “Hal’s data give us a detailed look at whether the snowpack that supplies much of the water supply for Northeastern Nevada changed over three decades.”

After three years of digitizing Klieforth’s notebooks, Schumer, along with graduate student Hal Voepel, can document the strong correlation between snowfall volume and variability in winter temperatures. “The key is to separate natural variation in temperature from those caused by human activities. Northern Nevada relies on mountain snowpack to store water until we need it in the irrigation season,” she said. “Changes in regional snowpack could affect local water management strategies.”

Schumer also thinks about how pollutants like mercury or nutrients such as nitrogen and phosphorus contained in the Tahoe Basin snowpack make their way to the lake. These nutrients can have a damaging effect on the lake’s ecosystem and water clarity. “There is great interest in excess nutrients entering the lake,” Schumer said. “But there have been few studies focused on nutrients entering the lake from the snowpack that builds up on the mountains around the lake during the winter.”

Schumer collaborates with fellow DRI scientist Daniel Obrist and graduate student Chris Pearson to collect samples from snowpack on the ground and snow falling from the sky. Using chemical data and measurements of snowfall like Klieforth’s, they intend to make estimates of the pollutants held in the snowpack each year.

Schumer, along with many DRI colleagues, is carrying on the climate research that Klieforth began three decades ago. Schumer is currently the associate director of the graduate program of hydrology at the University.

Klieforth, now 86, joined DRI in January 1965 and is Professor Emeritus at both the University and DRI. He splits his time between his two homes in Reno and Bishop, Calif. Klieforth still finds time to hike and explore the Sierra Nevadas, the area that sparked his interest in how weather interacts with vegetation and wildlife continues to fire his scientific curiosity. Having grown up in Marin County, Calif., Klieforth found himself naturally drawn to Lake Tahoe and the surrounding region.

“Lake Tahoe and its environs were in the same climate regime as Marin County,” he said. “They experienced the same storms and seasons. They were all part of my backyard, my background, and my life.”

By Guia Del Prado, 2013 Lake Tahoe Summit Report