WASHINGTON, Jan. 23 - The White House was told in the hours before Hurricane Katrina hit New Orleans that the city would probably soon be inundated with floodwater, forcing the long-term relocation of hundreds of thousands of people, documents to be released Tuesday by Senate investigators show.

A Homeland Security Department report submitted to the White House at 1:47 a.m. on Aug. 29, hours before the storm hit, said, "Any storm rated Category 4 or greater will likely lead to severe flooding and/or levee breaching."

The internal department documents, which were forwarded to the White House, contradict statements by President Bush and the homeland security secretary, Michael Chertoff, that no one expected the storm protection system in New Orleans to be breached.

"I don't think anyone anticipated the breach of the levees," Mr. Bush said in a television interview on Sept. 1. "Now we're having to deal with it, and will."

Other documents to be released Tuesday show that the weekend before Hurricane Katrina made landfall, Homeland Security Department officials predicted that its impact would be worse than a doomsday-like emergency planning exercise conducted in Louisiana in July 2004.

In that drill, held because of common knowledge that New Orleans was susceptible to hurricane-driven flooding, emergency planners predicted that in a Category 3 storm, one million people would be forced to move away, 17 percent of the nation's oil refining capacity would be knocked out and as many as 60,000 lives might be lost.

"Exercise projection is exceeded by Hurricane Katrina real-life impacts," the Aug. 27 department report said, two days before the storm hit New Orleans.

The loss of life in Hurricane Katrina was far less - at least 1,350 deaths have been confirmed so far - but the estimated number of dislocated residents was not far off.

A White House spokesman, asked about the seeming contradiction between Mr. Bush's statement on Sept. 1 and the warning as the storm approached, said the president meant to say that once the storm passed and it initially looked as if New Orleans had gotten through the hurricane without catastrophic damage, no one anticipated at that point that the levees would be breached.

The Senate investigators have also found evidence that at least some federal and state officials were aware last summer that the hurricane evacuation planning in the New Orleans area was incomplete.

"We're at less than 10 percent done with this trans planning when you consider the buses and the people," said a summary of a July briefing held with local, state and federal officials regarding a possible hurricane in Louisiana and referring to transportation planning. "If you think soup lines in the Depression were long, wait til you see the lines at these collection points," the summary said, referring to buses that were supposed to help pick up people to evacuate New Orleans.

Senator Susan Collins, Republican of Maine, who is chairwoman of the Senate Homeland Security and Governmental Affairs Committee, said that despite such evidence, officials from the Federal Emergency Management Agency had told investigators that leading up to Hurricane Katrina they believed that local and state governments could handle the evacuation on their own.

"It is another example of a lack of coordination and planning and a disconnect between what the FEMA officials' perception was and what the reality was facing state and local officials," Ms. Collins said.

Separately Monday, a Democrat on the House committee that is also investigating Hurricane Katrina urged Representative Thomas M. Davis III, Republican of Virginia, who is the chairman of the House inquiry, to enforce a subpoena presented to Secretary of Defense Donald H. Rumsfeld for documents related to the storm.

The Democrat, Representative Charlie Melancon of Louisiana, said in a letter that recent interviews by House investigators had produced evidence that "the Defense Department frustrated FEMA's attempts to get this aid delivered to the stricken region," and that the documents from the Pentagon were necessary to address the accusations.

A Defense Department spokesman declined to comment on the letter.

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