Using everything from hand-drawn maps and 911 reports to radar data and sophisticated mapping software, geographers at Louisiana State University have produced a preliminary atlas of the flood across two dozen parishes in the state.In some parishes with more resources, the maps show fine detail. Others are still rough. “In many parishes, they are trying to establish basic services for their people,” said Brant Mitchell, director of the Stephenson Disaster Management Institute at L.S.U. “They are not focused on extents.” He said that some parishes, like Ascension, where flooding was widespread, have not yet produced maps. Ascension’s flooding was estimated from 100-year flood maps from FEMA.