If you read the declaration, you'll get the feeling that the administration did anticipate pontential problems:

"The President today declared an emergency exists in the State of Louisiana and ordered Federal aid to supplement state and local response efforts in the parishes located in the path of Hurricane Katrina beginning on August 26, 2005, and continuing.

"The President's action authorizes the Department of Homeland Security, Federal Emergency Management Agency (FEMA), to coordinate all disaster relief efforts which have the purpose of alleviating the hardship and suffering caused by the emergency on the local population, and to provide appropriate assistance for required emergency measures, authorized under Title V of the Stafford Act, to save lives, protect property and public health and safety, or to lessen or avert the threat of a catastrophe in the parishes of.."

So we see how they perform when they foresee trouble...