September 11, 2001 is a defining moment in U.S. history, and its memories and emotions echo through the words of the 9/11 Commission:
At 8:46 on morning of September 11, 2001, the United States became a nation transformed. An airliner traveling at hundreds of miles per hour and carrying some 10,000 gallons of jet fuel plowed into the North Tower of the World Trade Center in Lower Manhattan. At 9:03, a second airliner hit the South Tower. Fire and smoke billowed upward. Steel, glass, ash, and bodies fell below. The Twin Towers, where up to 50,000 people worked each day, both collapsed less than 90 minutes later . . . More than 2,600 people died at the World Trade Center . . . [and] the death toll surpassed that at Pearl Harbor in December 1941.
This composite hydrograph offers a unique perspective on the events of September 11th as observed by a flow monitor located near the World Trade Center.
Note that this day started out like any normal day. That all changed at 8:46 AM when terrorists flew American Airlines Flight 11 into the North Tower of the World Trade Center. Much of Manhattan, including this area, was evacuated as rescue and recovery efforts began. This clearly was not a normal or average day. Instead, this flow monitor has documented its own account of a historic tragedy from a unique perspective. Although the perspective is different, the story remains compelling.
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Acknowledgement:
Special thanks are extended to the New York City Department of Environmental Protection for contributing this flow monitoring data and authorizing its use for this purpose.