NEW ORLEANS – Hurricanes Katrina and Rita severed 217 square miles of Louisiana's coastline and turned huge areas of land to water, according to a new U.S. Geological Survey study.

Survey scientists compared satellite images taken in 2004 with similar images from October 2005 to match areas that were wetlands, undeveloped dry land and farmland with what looked like open water several weeks after the storms.

In southeastern Louisiana, the study showed that the sea swallowed 79.2 square miles of land and wetlands east of the Mississippi River.

Of the total land lost, Plaquemines Parish took the brunt: 57.2 square miles. The biggest chunk came in a section of wetlands south of the St. Bernard hurricane levees, on the eastern side of the Mississippi River.

The New Orleans East Landbridge – the stretch of solid land and wetlands that straddles U.S. 90 in far eastern New Orleans – lost 1.4 square miles of marsh, and the Labranche wetlands on the south shore of Lake Pontchartrain lost 1.2 square miles.

Northshore marshes along the lake and next to the Mississippi Sound saw 2.1 square miles of land and marsh turn to water.

Also taking a big hit during Katrina were the Chandeleur Islands – the state's easternmost land mass. Katrina scraped 3.6 square miles of sand from the chain, and officials say it's unclear whether the sand will re-form into islands during the next few years.