This risk of devastation had been known for some time ; previous studies by FEMA and the Army Corps of Engineers had warned that a direct hurricane strike on New Orleans could lead to massive flooding , which would lead to thousands of drowning deaths , as well as many more suffering from disease and dehydration , as the flood waters slowly retreated from the city . This risk of devastation had been known for some time ; previous studies by FEMA and the Army Corps of Engineers had warned that a direct hurricane strike on New Orleans could lead to massive flooding , which would lead to thousands of drowning deaths , as well as many more suffering from disease and dehydration , as the flood waters slowly receded from the city .