Representatives of the Federal Emergency Management Agency and Massachusetts Department of Conservation and Recreation will host a meeting Sept. 4 to answer questions regarding the new federal flood maps released for some communities in Plymouth County. The expanded flood zones will require more landowners to purchase flood insurance. Officials will be available starting at 4 p.m. at Furnace Brook Middle School in Marshfield to review the maps individually with property owners, said Jeb Killion, a FEMA spokesman. A presentation will begin at 7 p.m. Killion said the evening will focus mainly on Marshfield and Scituate, but residents of Duxbury and other surrounding communities are welcome to attend. At the meeting, officials will explain how FEMA arrived at the new lines and how residents may be affected by a separate federal law passed last year that raises some flood insurance rates.