Featured Research

from universities, journals, and other organizations

Tackling the erosion of a special river island

Date:
December 14, 2010
Source:
Vanderbilt University
Summary:
Locke Island is a small island in a bend of the Columbia River in eastern Washington that plays a special role in the culture of local Indian tribes. Recently, it has begun eroding away at an alarming rate. Researchers are working to identify the cause of the increase in erosion.

Vanderbilt sedimentologist David Furbish, left, and undergraduate Grace Loy are using a stream table to study the currents that are causing Locke Island -- a small island in the Columbia River in eastern Washington that has special cultural significance to local Indian tribes -- to erode at an alarming rate.
Credit: Susan Urmy, Vanderbilt University

Locke Island is a small island in a bend of the Columbia River in eastern Washington that plays a special role in the culture of the local Indian tribes. Since the 1970s, however, it has been eroding away at a rate that has alarmed tribal leaders.

Related Articles


The island is part of the Hanford Reservation, which is managed by the Department of Energy.

So the DOE has turned to a team of researchers headed by David Furbish, professor of earth and environmental sciences (E&ES) at Vanderbilt, to study the river dynamics in the area to identify the cause of the increase in erosion and provide the scientific basis for evaluating the effectiveness of possible remedial measures.

As part of this effort, E&ES major Grace Loy has been conducting small-scale tests of the river flow around the island using a stream table, and graduate student John Roseberry is incorporating the results of these tests into a more detailed computer simulation. Loy presented the initial results of their study Dec. 16 in a poster paper at the annual meeting of the American Geophysical Union in San Francisco.

Locke Island's difficulties began when the east bank of the river adjacent to it began to collapse. The resulting landslide continued to grow for the next 20 years, increasingly pinching down the channel that flows around that side of the island. Concern over the impact that this was having on the island prompted scientists at DOE's Pacific Northwest National Laboratory to begin monitoring the situation in 1994. According to their records, as much as 120 feet of the island bank facing the landslide eroded away between 1996 to 2006, peaking in 1997 during a period of unusually high river flow. Another episode of erosion took place during high flows in 2002. However, the landslide has not grown since 1998 when ponds on the bluff above thought to be responsible were drained.

"The generally accepted explanation for the increased erosion has been that the narrowing of the channel forced the water flowing through it to speed up significantly and the stronger current wore away the side of the island more rapidly," Loy said. "We were skeptical of this explanation and our analysis suggests that it isn't what happened."

The stream table consists of a straight wooden channel with a large tank of water at one end. A mockup of the island and the landslide sit halfway down. Bright lights and a video camera are aimed down on the channel from above. A test consists of running water at different velocities down the channel and dropping small green beads into the water at the top of the channel. As the beads are carried down the channel their motion is recorded by the video camera. The images are then analyzed by computer to map the velocity of the currents at different locations.

"When we add the landslide, we find that the water builds up in front of the narrow channel and this steers much of the water into the larger channel," Loy said. As a result, instead of flowing at the same speed in the large channel and flowing much more rapidly in the narrow channel, the current in both channels increases slightly compared to what it was before the landslide.

"We predicted this steering effect but it was much larger than we expected in our tests. The flow was about 50/50 between the two channels without the landslide. With the landslide it was as high as 75/25 percent," Loy said.

Furbish cautioned that they cannot yet conclude that this is exactly what is happening on the river: There are certain aspects of the stream-table studies that cannot be scaled up. So they must wait for the completion of the computer simulations expected in the next six months before they can estimate how strong this steering effect is on the river itself.

The Vanderbilt team was recruited for the study by the Consortium for Risk Evaluation with Stakeholder Participation, a multi-university consortium led by Vanderbilt and funded by DOE to work with stakeholder groups to develop cost-effective and politically acceptable methods for cleaning up the nation's nuclear weapons production sites.

"Since I was a boy, I have admired Native Americans," Furbish said. "So it is very exciting to be working on a project that can help them protect land that is special to them."


Story Source:

The above story is based on materials provided by Vanderbilt University. Note: Materials may be edited for content and length.


Cite This Page:

Vanderbilt University. "Tackling the erosion of a special river island." ScienceDaily. ScienceDaily, 14 December 2010. <www.sciencedaily.com/releases/2010/12/101214181955.htm>.
Vanderbilt University. (2010, December 14). Tackling the erosion of a special river island. ScienceDaily. Retrieved November 24, 2014 from www.sciencedaily.com/releases/2010/12/101214181955.htm
Vanderbilt University. "Tackling the erosion of a special river island." ScienceDaily. www.sciencedaily.com/releases/2010/12/101214181955.htm (accessed November 24, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Monday, November 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

3D Map of Antarctic Sea Ice to Shed Light on Climate Change

3D Map of Antarctic Sea Ice to Shed Light on Climate Change

Reuters - Innovations Video Online (Nov. 24, 2014) A multinational group of scientists have released the first ever detailed, high-resolution 3-D maps of Antarctic sea ice. Using an underwater robot equipped with sonar, the researchers mapped the underside of a massive area of sea ice to gauge the impact of climate change. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Car Park Solution for Flexible Green Energy

Car Park Solution for Flexible Green Energy

Reuters - Innovations Video Online (Nov. 24, 2014) A British solar power start-up says that by covering millions of existing car park spaces around the UK with flexible solar panels, the country's power problems could be solved. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

AFP (Nov. 23, 2014) The arable district of Kenema in Sierra Leone -- at the centre of the Ebola outbreak in May -- has been under quarantine for three months as the cocoa harvest comes in. Duration: 01:32 Video provided by AFP
Powered by NewsLook.com
NY Gov. on Flood Prep: 'prepared for the Worst'

NY Gov. on Flood Prep: 'prepared for the Worst'

AP (Nov. 23, 2014) First came the big storm. Now comes the big melt for residents of flood-prone areas around Buffalo. New York's governor says officials are preparing for the worst as the temperature is expected to rise and potentially melt several feet of snow. (Nov. 23) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins