Navigation Links
'Thermal pollution' in rivers not fully mediated by gravel augmentation

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
USDA Forest Service, Pacific Northwest Research Station

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:
(Date:11/4/2015)... 2015 --> ... by Transparency Market Research "Home Security Solutions Market - Global ... - 2022", the global home security solutions market is expected to ... The market is estimated to expand at a CAGR ... 2022. Rising security needs among customers at homes, the ...
(Date:10/29/2015)... , Oct. 29, 2015  Rubicon Genomics, ... for U.S. distribution of its DNA library preparation ... and Rubicon,s new ThruPLEX Plasma-seq kit. ThruPLEX Plasma-seq ... the preparation of NGS libraries for liquid biopsies--the ... diagnostic and prognostic applications in cancer and other ...
(Date:10/27/2015)... 27, 2015 Munich, Germany ... Mapping technology (ASGM) automatically maps data from mobile eye ... , so that they can be quantitatively analyzed ... Munich, Germany , October 28-29, 2015. SMI,s ... from mobile eye tracking videos created with SMI,s ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... ... November 24, 2015 , ... InSphero AG, the leading supplier ... models, has promoted Melanie Aregger to serve as Chief Operating Officer. , ... the management team and was promoted to Head of InSphero Diagnostics in ...
(Date:11/24/2015)... 2015 /CNW Telbec/ - ProMetic Life Sciences Inc. (TSX: PLI) ... Pierre Laurin , President and Chief Executive Officer of ... Piper Jaffray 27 th Annual Healthcare Conference to be ... 2015. st , at 8.50am (ET) and ... the day. The presentation will be available live via a ...
(Date:11/24/2015)... , Nov. 24, 2015 HemoShear ... on discovering drugs for metabolic disorders, announced today ... to its Board of Directors (BOD). Mr. Watkins ... of Human Genome Sciences (HGS), and also served ... Jim Powers , Chairman and CEO ...
(Date:11/24/2015)... YORK , November 24, 2015 ... in a European healthcare ... which the companies will work closely together in identifying European ... unmet medical need. The collaboration is underpinned by a significant ... fund. This is the first investment by Bristol-Myers Squibb in ...
Breaking Biology Technology: