How The Mighty Mississippi Saved Shores From BP Oil Spill
Originally published on US News.
Most of us have by now seen the happy, sunny commercials BP has sprinkled across the television landscape in the past few months, welcoming Americans back to the beaches in Florida, Louisiana, and other southern coasts affected by the Deepwater Horizon BP oil spill in the spring of 2010.
The ads sponsored by BP feature state and local officials who are obviously relieved that predictions of oil contamination along the coastlines never reached the levels some had initially predicted. They show lovely beaches, and remind viewers that the BP oil spill could have been much, much worse.
Now, a study from researchers at the University of Pennsylvania published in PLoS ONE may help explain why much of the crude oil from the Deepwater Horizon BP oil spill never made it to land: The Mississippi River pushed back–and kept much of the oil offshore.
“We noticed that there was a big disconnect between the forecasts of where the oil was going to be the next day and where the oil actually was the next day,” said Douglas Jerolmack, one of three geoscientists who used publicly available data sets to look at whether the force of the Mississippi River emptying into the Gulf of Mexico could have plausibly countered some of the effects of the BP oil spill.
The first place researchers looked was outside the usual scope of ocean circulation models that generally don’t take “secondary” forces like major rivers emptying into the oceans into account when they predict where things (like oil) will travel in the ocean. They found that the Mississippi River had, in fact, protected the coastline.
“That maybe shouldn’t be a surprise, because these computer models were not generated to forecast the movement of oil,” he said. “They were generated to forecast the movement of water.”
As the researchers looked through the data, what they found was a very fortunate combination of natural forces that protected the coastline. While ocean circulation models were predicting oil slick migration in the Gulf of Mexico–and potentially even along the eastern U.S. coastline–they weren’t looking at the effects of secondary eddy slopes or Mississippi River hydrodynamics.
Instead, the data showed that, under conditions of relatively high river discharge and weak winds, a freshwater mound could form around the Mississippi River Delta and push back against the incoming water, keeping the oil from reaching the coastline…
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