Large parts of the US city of New Orleans are still at risk of flooding in a major storm, a report has found.
Many New Orleans residents are still rebuilding their homes
Nearly two years after Hurricane Katrina lashed the US Gulf Coast, $1bn (£502m) has been spent to fix hurricane-protection systems.
But many areas of the city would still be vulnerable in a storm much weaker than Katrina, the US Army Corps of Engineers' study found.
Nearly 1,700 people were killed in the wake of the devastating hurricane.
Mapping the risk
Storm-protection gates and other construction projects had left some areas of the city better protected than in 2005, the corps - which is leading the reconstruction - found.
But in many other areas, the risk of flooding was the same - some hurricane-protection systems were repaired only to their pre-Katrina levels rather than upgraded.
With many residents still rebuilding in the hope of returning to New Orleans, the project found parts of the city were still at risk of flooding from what it describes as a 1-in-100 storm. Katrina was a much stronger, 1-in-400 storm.
"What we're doing here is showing people what the magnitude of the risk is," the corps' chief engineer, Lt Gen Robert Van Antwerp, said.
"The whole purpose of providing this information is so people can make a personal decision."
The corps also created a website that lets residents assess storm-damage risks in the city block-by-block, based on a series of detailed maps and statistical analysis.
The maps were developed by testing aspects of the New Orleans landscape, such as topography and levees, against 152 possible storm types.
It is not certain that computer modelling can accurately predict exactly how any storm would affect the city, but they will be used to help the corps plan its rebuilding projects and by insurance companies for risk assessment.
The corps is due to finish rebuilding the hurricane-protection systems in 2011.