Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Deforestation in snowy regions causes more floods

04.10.2012
New research suggests that cutting down swaths of forest in snowy regions at least doubles – and potentially quadruples – the number of large floods that occur along the rivers and streams passing through those forests.

For decades, the common perception in hydrology has been that deforestation in such areas made seasonal floods bigger on average, but had little effect on the number of large floods over time, said geoscientist Kim Green of the University of British Columbia.

But a new study by Green and her co-author Younes Alila published today in Water Resources Research, a journal of the American Geophysical Union, suggests that deforestation consistently causes more floods – both big and small. In the interior regions of North America, many creeks and rivers get most of their flow from melting snow accumulated during winter storms in mountainous areas.

How much water flows down these streams depends not only on how much snow falls upstream, but how fast the snow melts. But deforestation shines a new – and glaring – light on this water source. While ordinarily the trees keep the melting under control by shielding snow from the sunlight, “as soon as you get rid of the trees, the snow melts faster,” said Green. “It’s that simple.”

The difference between Green and Alila’s study and what hydrologists have historically done is how they crunched the data. In the past, hydrologists used a technique called chronological pairing – they compared each year’s flood data from a stream in a deforested area to that year’s data from a nearby, fully forested stream. This allowed the scientists to describe how floods become larger on average in deforested areas. But chronological pairing doesn’t deduce how much more frequent these floods might be. For this, scientists need a method called frequency pairing.

In frequency pairing, researchers review a decade or more of data all at once to determine a flood’s return period – how often a flood of a given size recurs. Green’s study is the first to use frequency pairing to explore how deforestation affects flood frequencies in streams in mountainous regions where at least half the annual precipitation falls as snow. She analyzed data from four creeks – Camp Creek, Redfish Creek and 240 Creek in British Columbia and Fool Creek in Colorado. With two creeks, Fool and Camp, she studied data from the past few decades in comparison to nearby, similar creeks where the terrain had not been deforested. With the other two, Redfish and 240, she used flood data generated by a computer model to study the simulated effect of deforestation of the terrain over more than 90 years.

The analysis showed that, in all four waterways, deforestation turned 10-year floods into three-to- five-year floods. Twenty-year floods recurred every 10 to 12 years. Most dramatically, in 240 Creek, 50 year floods happened every 13 years, almost four times as often. “Once you look at how the frequency has changed,” Green said, “you start to realize that deforestation has had a pretty dramatic effect on floods.”

Green’s model for how deforestation affects the flow of water is “something that’s going to be tested in other places many times, to see if their theory actually holds,” said Sandy Verry, a retired U.S. Forest Service hydrologist in Grand Rapids, Minn., who was not involved in the study but has studied streams using chronological pairing in the past. Verry said he believes Green’s conclusions about flood rates to be reasonable.

Until recently, the decades of data needed for frequency pairing data was scarce, Verry said, because hydrologists only started recording stream measurements in the North American West about 50 years ago. He expects there will be a “plethora” of further studies that study the frequency of floods over a broad array of deforested landscapes, including streams that flow into farmlands and cities. “There’s a whole realm of application to forest landscapes at lower elevations and flatland that this can be applied to,” Verry said.

Notes for Journalists

Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this paper by clicking on this link:

http://dx.doi.org/10.1029/2012WR012449

Or, you may order a copy of the paper by emailing your request to Sean Treacy at
streacy@agu.org. Please provide your name, the name of your publication, and your phone

number.

Neither the paper nor this press release are under embargo.

Title:
“A paradigm shift in understanding and quantifying the effects of forest harvesting on floods in

snow environments”

Authors:
Kim Green and Younes Alila: Department of Forest Resources Management, University of British Columbia, Vancouver, BC, Canada.
Contact information for the authors:
Kim Green, (250) 352-6725, Email: apexgeo.kg@telus.net

Sean Treacy | American Geophysical Union
Further information:
http://www.agu.org

More articles from Earth Sciences:

nachricht Responses of benthic foraminifera to changes of temperature and salinity
14.01.2019 | Science China Press

nachricht 'Realistic' new model points the way to more efficient and profitable fracking
14.01.2019 | DOE/Los Alamos National Laboratory

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Nanocellulose for novel implants: Ears from the 3D-printer

Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.

It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:

Im Focus: Elucidating the Atomic Mechanism of Superlubricity

The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.

One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...

Im Focus: Mission completed – EU partners successfully test new technologies for space robots in Morocco

Just in time for Christmas, a Mars-analogue mission in Morocco, coordinated by the Robotics Innovation Center of the German Research Center for Artificial Intelligence (DFKI) as part of the SRC project FACILITATORS, has been successfully completed. SRC, the Strategic Research Cluster on Space Robotics Technologies, is a program of the European Union to support research and development in space technologies. From mid-November to mid-December 2018, a team of more than 30 scientists from 11 countries tested technologies for future exploration of Mars and Moon in the desert of the Maghreb state.

Close to the border with Algeria, the Erfoud region in Morocco – known to tourists for its impressive sand dunes – offered ideal conditions for the four-week...

Im Focus: Programming light on a chip

Research opens doors in photonic quantum information processing, optical signal processing and microwave photonics

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a new integrated photonics platform that can...

Im Focus: Physicists uncover new competing state of matter in superconducting material

A team of experimentalists at the U.S. Department of Energy's Ames Laboratory and theoreticians at University of Alabama Birmingham discovered a remarkably long-lived new state of matter in an iron pnictide superconductor, which reveals a laser-induced formation of collective behaviors that compete with superconductivity.

"Superconductivity is a strange state of matter, in which the pairing of electrons makes them move faster," said Jigang Wang, Ames Laboratory physicist and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

11th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Aachen, 3-4 April 2019

14.01.2019 | Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

 
Latest News

Scientists coax proteins to form synthetic structures with method that mimics nature

15.01.2019 | Life Sciences

Next generation photonic memory devices are light-written, ultrafast and energy efficient

15.01.2019 | Information Technology

Viennese scientists develop promising new type of polymers

15.01.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>