Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New climate research reveals growing risk of water shortages and flooding in California

08.02.2006


If the world continues to burn greenhouse gases, California may have an increased risk of winter floods and summer water shortages, even within the same year. This scenario may be more severe in future El Niño years.


©2003 American River Conservancy
A waterfall on the North Fork of the American River, in the foothills of California’s eastern Sacramento Valley.


Photo courtesy of Tuolumne River Coalition. The Lower Tuolumne River in California’s Great Central Valley.



New research by Lawrence Livermore National Laboratory (LLNL) scientists shows that global warming is likely to change river flows in ways that may result in both increased flood risk and water shortages. The predictions assume atmospheric carbon dioxide concentration doubles from preindustrial levels.

The amount of water flowing in California’s rivers needs to be just right. Too much brings a risk of flooding; too little causes reservoir levels to drop.


As temperatures warm as a result of carbon emission, more rain than snow falls at higher elevations. For the areas that do receive snow, melt occurs sooner.

The research shows that this well-known scenario – in which global warming causes an increase in wintertime river flows and a reduction in spring and summer flows – is more robust than previously thought.

“It seems unlikely that any changes in precipitation will be large enough to eliminate these problems,” said Philip Duffy, an LLNL physicist and director of the Institute for Research on Climate Change and its Societal Impacts, a University of California Intercampus Research Program. Furthermore, in an El Niño (a naturally occurring climate fluctuation) season, these problems may be more severe.

California’s water infrastructure is very efficient at providing an adequate water supply and minimizing flood risk. The system, however, works well only in a climate that includes large amounts of mountain snow. Melting snow keeps reservoirs full in the late spring and summer, after rain and snowfall have stopped. Snow acts as a natural reservoir, with a volume close to that of manmade reservoirs.

As global warming ensues, more precipitation will be in the form of rain rather than snow. Also, what snow remains will melt earlier in the year. These changes will result in higher river flow rates in California’s major rivers during winter and lower flows during spring and summer, when flows are largely from snowmelt.

“Even if total flows over the whole year are the same, these changes could jeopardize water supplies, because it may not be possible for reservoirs to capture the increased winter flows,” said Edwin Maurer, a professor at Santa Clara University and lead author of the research that appears in the Jan. 27 edition of the journal Geophysical Research Letters. “This problem would be compounded by an increased risk of wintertime flooding resulting from higher river flow rates,” he said.

This would force water managers to reduce reservoir water levels to provide extra space for capturing increased winter flood surges, which would further reduce the overall year’s water supply.

“In an El Niño year, which brings more rain than a typical year, there would be an increase (versus today) in the year-to-year variability in river flow rates, which would make life complicated for people who manage the water supply,” Duffy said.

The researchers simulated only monthly mean river flows, so they can’t quantitatively assess flood risk, which depends on daily-timescale river flows. However, the monthly flows are high enough to indicate that flood risk would be much higher.

“In particular, there will be increased wintertime river flows and lower spring and summer flows whether future precipitation increases or decreases modestly,” Maurer said. “It seems unlikely that the potential problems can be avoided by changes in precipitation.” This finding was published earlier this year by Maurer and Duffy.

The newest paper by Maurer, Duffy, and Seran Gibbard of LLNL’s AX Division investigates effects on California river flows of a hypothetical future-climate El NiÑo. El NiÑo is a naturally occurring climate oscillation that typically produces increased precipitation, river flows and flood risk in California.

The team’s work has some limitations: The researchers assumed that the strength of an El Niño, as measured by departures of sea-surface temperatures from long-term average values, will be the same in the future as today. They did this because climate models don’t agree on how the strength of an El Niño is likely to change.

Founded in 1952, Lawrence Livermore National Laboratory has a mission to ensure national security and to apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy’s National Nuclear Security Administration.

Anne Stark | EurekAlert!
Further information:
http://www.llnl.gov

More articles from Earth Sciences:

nachricht Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute

nachricht Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>