Saturday, February 12, 2011

Flood runoff a murky soup

Ever wonder what happens when a flooding river hits the ocean? The ocean turns into a murky soup.

Check out this amazing satellite image of an Australian flood plume (right) as muddy water heads for the Great Barrier Reef.

Up close, the water looked like this (below left).

What are the effects of muddy water on the ocean? Floods are natural, and ocean ecosystems can tolerate high sediment loads now and then.

But bad things can happen when floodwaters dump too much freshwater on coral reefs, when runoff is contaminated with toxic chemicals, or when ocean ecosystems are stressed from high nutrient loads and routine sediment loading, death of vulnerable organisms like coral can be a result. Floods don't do this dirty work alone, but they can play a role.

This muddying of the ocean is not unique to massive floods like in Australia,a more modest flood near Seattle also turned the ocean into a murky brown soup (right).

Secchi disk measurements of the Seattle Bay showed 8 inches of visibility, way below average for winter, when visibility can approach 30 feet--see my Swim Around Bainbridge Island for some photos.

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