Using an optical plume velocity technique, Timothy Crone and Maya Tolstoy, Columbia University, USA, have estimated the amount of oil released from the Deepwater Horizon oil spill.
The technique employs underwater cameras which capture high-resolution video of the turbulent flow and allow pixel-by-pixel analysis of the flow. The analysis indicated a flow of about 56,000 barrels a day (1.0 x 10–1 m3s–1) for the initial period from 22nd April to 3rd June, when the riser was cut. After this, the rate increased to about 68,000 barrels a day (1.2 x 10–1 m3s–1).
Accounting for the time elapsed, and the oil collected by BP at the seafloor (804,877 barrels), a total of 4.4 million barrels of oil (±20 %) is estimated to have escaped. This figure is in agreement (within the margin of error) with the US government’s Flow Rate Technical Group’s most recent estimate of 4.1 million barrels.