Turbulent forces within river plumes affect spread

Aug 08, 2012

When rivers drain into oceans through narrow mouths, hydraulic forces squeeze the river water into buoyant plumes that are clearly visible in satellite images. Worldwide, river plumes not only disperse freshwater, sediments, and nutrients but also spread pollutants and organisms from estuaries into the open ocean. In the United States the Columbia River, the largest river by volume draining into the Pacific Ocean from North America, generates a plume at its mouth that transports juvenile salmon and other fish into the ocean. Clearly, the behavior and spread of river plumes, such as the Columbia River plume, affect the nation’s fishing industry as well as the global economy.

A delicate balance between density and velocity controls turbulent mixing within the plume and how far river plumes extend into the deep ocean. On the other hand, coastal winds and currents affect the shape and orientation of the plumes. However, current understanding of momentum changes along a river plume is limited by poorly constrained numerical models and sparse remote sensing data.

In a new study, Kilcher et al. document velocity, density, and turbulence along the centerline of the plume at a high resolution for 10 tidal cycles. The authors find that turbulence varied by 2 to 3 orders of magnitude within a single tidal cycle as well as between cycles. The authors also show that turbulence, which is most vigorous at the beginning of the strongest ebbs, dramatically reduces the velocity of water at the river mouth. The quickly decelerating plumes tend to spread less into the deep ocean. Their observations supplement satellite data and could help to fine-tune numerical models that predict the behavior and spread of river plumes as they drain into coastal waters.

Explore further: Study links polar vortex chills to melting sea ice

More information: “The role of turbulence stress divergence in decelerating a river plume” Journal of Geophysical Research-Oceans, doi:10.1029/2011JC007398 , 2012

add to favorites email to friend print save as pdf

Related Stories

Water mission reveals insight into Amazon plume

Sep 03, 2010

(PhysOrg.com) -- ESA's SMOS water mission has taken another step forward by demonstrating that it will lead to a better understanding of ocean circulation. Using preliminary data, scientists can clearly see ...

Satellites Spot Mighty Mississippi – In The Atlantic

Sep 15, 2005

Scientists using satellite imagery found that at least 23 percent of the water released from the mouth of the Mississippi River from July through September 2004 traveled quite a distance - into the Gulf of ...

Monitoring Mississippi Delta flood from space

May 20, 2011

As floodwaters roll downstream, earth scientists at the University of Pennsylvania are keeping a watchful eye on the Mississippi Delta using satellite images and measurements of the sea surface in the Gulf ...

Mersey River tidal power station proposed

Nov 22, 2005

The Mersey River may soon become the first river in Britain to generate electricity by tidal activity. The river, known for its leaping salmon, is now being tested as a possible renewable energy source.

Recommended for you

Tropical Storm Dolly forms, threatens Mexico

2 hours ago

Tropical Storm Dolly formed off Mexico's northeastern coast on Tuesday and headed toward landfall in Tamaulipas state, threatening to spark floods and mudslides, forecasters said.

Giant garbage patches help redefine ocean boundaries

4 hours ago

The Great Pacific Garbage Patch is an area of environmental concern between Hawaii and California where the ocean surface is marred by scattered pieces of plastic, which outweigh plankton in that part of ...

New satellite maps out Napa Valley earthquake

6 hours ago

Scientists have used a new Earth-observation satellite called Sentinel-1A to map the ground movements caused by the earthquake that shook up California's wine-producing Napa Valley on 24 August 2014.

Rainfall monitoring with mobile phones

6 hours ago

Agriculture, water resource management, drought and flood warnings, etc.: rainfall monitoring is vital in many areas. But the observation networks remain insufficient. This is not the case for antennas for ...

User comments : 0