Initial Landsat satellite analysis of wetlands indicate some change in area and shape in the Breton Sound area below New Orleans, the lower Pearl River Basin, the Missississippi River Delta, and the North Shore marshes bordering Lake Pontchartrain. See more here 

USGS Responding to the need for help:

In response, the Louisiana State Police requested the assistance of USGS scientists to provide “geo-addressing” to supplement street addresses by providing longitudinal and latitudinal coordinates. Depending upon the needs of emergency responders, these coordinates are then expressed in a variety of ways. For example, emergency responders who are not equipped with functioning Global Positioning System equipment might request maps with geographic coordinates overlaid upon grids of street addresses. Responders who do have functioning GPS equipment might request the coordinate data in a digital form that can be sent directly to GPS equipment.

The USGS scientists provide the desired coordinate information to the LGS, who then distributes it to a variety of governmental agencies participating in search and recovery efforts. The LGS has worked with at least 20 agencies in these efforts, and the USGS has currently assisted with thousands of calls (and sometimes e-mail messages) from stranded hurricane victims, either directly or indirectly via individuals who know where victims are stranded. In these efforts, USGS scientists have produced over 3,000 tabloid maps and 40 poster maps.

In addition to their work linking geographic coordinates and street addresses, the USGS is also providing mapping support for a variety of governmental agencies. The U.S. Army Corps of Engineers, for example, has sought USGS assistance to provide up-to-date maps of the New Orleans levee system. Along with these maps, the USGS has also provided USACE with geo-coded addresses for water pumps located in the city.

With assistance from the U.S. Fish and Wildlife Service, the USGS has also been providing geospatial support at the Federal Emergency Management Agency’s command post in Metairie, La. Maps and spatial data are provided to various task forces from numerous state and federal agencies to aid in recovery activities. Geospatial products are updated daily and are delivered to recovery teams every morning prior to their deployment.

See http://www.nwrc.usgs.gov/hurricane/katrina.htm