A floodplain is defined as the land area along a river, stream or waterway that is expected to be under water during a storm event. The Federal Emergency Management Agency
is responsible for identifying and mapping the limits of floodplains, and for administering the National Flood Insurance Program. Although floodplains can be defined for any storm event, the floodplain associated with the “100-year” storm (also known as the “1% chance” storm) is typically used to regulate construction and development. You can use the Maryland Department of the Environment's "DFIRM"
tool or FEMA’s Map Service Center
to find floodplain maps and other information for your area of interest.