Navigation Links
'Thermal pollution' in rivers not fully mediated by gravel augmentation
Date:6/8/2011

Although adding gravel to a river to replace lost sediments won't likely cool the whole river channel, it can create cool water refuges that protect fish from thermal pollution, according to a U.S. Forest Service Pacific Northwest Research Station study.

The researchfeatured in the June 2011 issue of Science Findings, a monthly publication of the stationis among the first to explore the interplay between sub-surface water flow and temperature in large rivers and is helping to guide river restoration strategies in the Pacific Northwest.

In the study, which began in 2006, station research hydrologist Gordon Grant and Oregon State University colleagues Barbara Burkholder and Roy Haggerty examined the effect of subsurface water flow through riverbed sedimenta process known as "hyporheic flow"on daily minimum and maximum water temperatures. The focus of their study was Oregon's Clackamas River, which, at the time, was undergoing intensive restoration planning efforts led by Portland General Electric (PGE) as part of the relicensing process for the river's hydroelectric system. The addition of gravel to the large river as part of these effortsaimed primarily at reversing changes in river channel morphology that have resulted from sediment transport being interrupted by the damsallowed the researchers to explore whether doing so had any measurable effect on reducing "thermal pollution," or unusually high water temperatures caused by human activities like dam operation, logging, and wastewater treatment.

"Previous work suggested that water emerging from gravel bars might actually be cooler than the surrounding water," said Grant.

The research team hypothesized that the continual cycling of subsurface water through the riverbedduring which cool nighttime water would travel through the gravel bar, exiting and mixing with the stream during the warmer daytimewould have a "buffering" effect that would keep the river's daily peak temperatures down, but not necessarily change the river's overall mean temperature. To explore their hypothesis, they mapped the locations of gravel bars along a 15-mile stretch of the river and documented the temperature of water cycling into and out of each of them.

They found 52 temperature differences within the stretch of the Clackamas, with temperatures at these locations from 1 to 4 degrees cooler than the main channel. The researchers were then able to link the cooler areas with specific gravel bar features and with specific times and locations within the Clackamas to create models that depicted the subsurface flow patternsultimately revealing that a very small percentage of the river's water actually passed through the gravel bars, making any overall effect on the mean temperature minute.

"Results showed a hundredth of a degree of temperature change through a single bar," said Grant. "Not much."

This finding suggests that gravel augmentation alone is not likely to have a significant temperature-mediating effect in large rivers. However, the work demonstrated that gravel augmentation may provide local habitat benefits to fish and small invertebrates by creating cool areas within rivers where they can seek refuge during hot weather.


'/>"/>

Contact: Yasmeen Sands
ysands@fs.fed.us
360-753-7716
USDA Forest Service, Pacific Northwest Research Station
Source:Eurekalert

Related biology news :

1. Scientists locate apparent hydrothermal vents off Antarctica
2. Case Western Reserve University grants option to startup Thermalin Diabetes Inc.
3. SMU geothermal conference
4. Environmental engineering students and faculty study Passaic River pollution
5. E-waste pollution a threat to human health, new research suggests
6. Air pollution near Michigan schools linked to poorer student health, academic performance
7. Air pollution exposure affects chances of developing premenopausal breast cancer
8. Latest report on North American industrial pollution reveals impacts on our shared water environment
9. Cephalopods experience massive acoustic trauma from noise pollution in the oceans
10. Study: Emissions trading doesnt cause pollution hot spots
11. The dark side of spring? Pollution in our melting snow
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/21/2016)... 21, 2016 NuData Security announced today that ... of principal product architect and that Jon ... customer development. Both will report directly to ... moves reflect NuData,s strategic growth in its product ... customer demand and customer focus values. ...
(Date:6/15/2016)... ALBANY, New York , June 15, 2016 ... published a new market report titled "Gesture Recognition Market ... Trends and Forecast, 2016 - 2024". According to the ... at USD 11.60 billion in 2015 and is ... and reach USD 48.56 billion by 2024.  ...
(Date:6/7/2016)... , June 7, 2016  Syngrafii Inc. and ... business relationship that includes integrating Syngrafii,s patented LongPen™ ... project. This collaboration will result in greater convenience ... credit union, while maintaining existing document workflow and ... ...
Breaking Biology News(10 mins):
(Date:11/30/2016)... , November 30, 2016 The global ... few players hold a dominant share in the overall ... Laboratories International, Inc., and Merck KGaA, held a lion,s ... Transparency Market Research observes that these companies are expected ... development products that are do not require rabbit pyrogen ...
(Date:11/30/2016)... VANCOUVER , Nov. 30, 2016 /PRNewswire/ -  Equicare ... coordination solutions, has been recognized as one of the ... 100, an annual international listing that distinguishes the top ... "We,ve pushed a great step forward this year continually ... growing our own customer base and team," says ...
(Date:11/30/2016)... -- Part of 5m$ Investment in Integrated Drug ... , ... today announced that it had successfully completed the expansion of ... increased the Screening Collection to over 400,000. The new compounds ... the company. This expansion, complemented by new robotics and compound ...
(Date:11/30/2016)... Triangle Park, NC (PRWEB) , ... November 30, ... ... development company engaged in the development of a new orally administered treatment for ... testing and neuroimaging results of a Phase 2a clinical trial of T3D-959 in ...
Breaking Biology Technology: