Hurricane Katrina cut across a wide swath of the southern United States Monday, leaving devastation in its wake from Florida, through Alabama, Mississippi and Louisiana. Hundreds if not thousands of people are dead, hundreds of thousands are without power and hundreds of thousands more who fled before the storm have no idea whether they have homes to return to.

Relief officials have made re-establishing transportation and communication links the top priority. Without electricity, officials are having a difficult time assessing the scope of this unprecedented natural disaster. Families aren't able to contact loved ones. And with many roads and bridges under water, rescue and relief efforts are hampered at nearly every turn. Michael Brown, Director of the Federal Emergency Management Agency, who is coordinating the federal government's rescue and relief efforts, says it's a very sobering scene.

For example, hospitals had to be evacuated because of flooding. Mr. Brown says FEMA is airlifting additional medical teams to take care of patients. California Urban Search and Rescue teams that have experience in swift water and deep water rescue had to be dispatched into some of the neighborhoods of New Orleans to start rescue efforts there.

Woody Gagliano is president of Coastal Environments, a Louisiana company that specializes in coastal restoration. "People have been forced into their attics and have had to cut escape hatches in the roofs to reach the top where they're being rescued by boats and helicopters," he says. Mr. Gagliano says he fears that when the waters finally recede, they will find that people who were not agile enough to escape in that fashion, drowned in their homes.

The U.S. Gulf coast has long expected some kind of devastating storm to strike the New Orleans area. Mr. Gagliano, who's spent the past three decades urging improved disaster preparedness, says the geography of the region makes it especially vulnerable. That's because developers in Louisiana and elsewhere in the Mississippi Delta have built on sediment that has been pushed out into the Gulf over thousands years by the Mississippi River. And over that time, Mr. Gagliano points out, the river shifts its position, swinging back and forth like a giant pendulum. The sediment builds up and builds a ridge and so the development and all of the infrastructure is clustered along the ridges.

Mr. Gagliano says it could take weeks, perhaps months, for the water trapped on the developed side of these ridges to drain back into the Gulf. But that won't happen without some help, because in these bowls, these depressions, some of which are two to three meters below sea level, they will not drain by gravity drainage. He says the water will have to be pumped out.

In the meantime, FEMA director Michael Brown says that sustaining lives is the highest priority. The government is providing meals, water and ice, and will be building shelters -- the basics, he says, that people are going to need in the immediate future. There are literally thousands of people in shelters that are not going to be able to return for some time, and most have no homes left to return to at all.

Still, Woody Gagliano is confident the region will be restored. As he says, "New Orleans is one of the world's great cities, and I have every confidence in the world that we will restore it and it will survive."

Survival is high on the minds of everyone in the area as they begin to pick up the pieces of their lives after the worst natural disaster ever to hit the mainland United States.