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Resource Index Glossary Actuarial Rates. Rates established by the Federal In- surance Administration pursuant to Flood Insurance Studies for individual communities. These rates are set in accordance with the National Flood Insurance Program (NFIP) and accepted actuarial principles. Subject to various other limitations, actuarial rates are applicable only after the publication and effective date of a community's Flood Insurance Rate Map (FIRM). Base Flood Elevation (BFE). The elevation for which there is a one-percent chance in any given year that flood levels will equal or exceed it. The BFE is de- termined by statistical analysis of streamflow records for the watershed and rainfall and runoff characteris- tics in the general region of the watershed. Coastal High Hazard Area. The portion of a coastal floodplain that is subject to high velocity waters caused by tropical storms, hurricanes, northeasters, or tsunamis. :\IFIP regulations for Coastal High Hazard Areas apply where tides, storm waves and surges, and local geographic characteristics combine to produce a breaking wave of three feet or more. Debris Impact Loads. Loads induced on a structure by solid objects carried by flood water. Debris can include trees, lumber, displaced sections of struc- tures, tanks, runaway boats, and chunks of ice. Debris impact loads are difficult to predict accurately, yet rea- sonable allowances must be made for them in the de- sign of potentially affected structures. Encroachment. Any physical object placed in a flood- plain that hinders the passage of water or otherwise affects flood flows. Existing Construction. Those structures already exist- ing or on which construction or substantial im- provement was started prior to the effective date of a community's floodplain management regulations. First Floor. The floor that is level with or immediately above the main point of entry into the building. For residences, it is additionally that floor that comprises the main living area of the dwelling. Flood or Flooding. A general and temporary condi- tion of partial or complete inundation of normally dry land areas. Flooding results from the overflow of in- land or tidal waters or the unusual and rapid accumu- lation of surface water runoff from any source. u.s. Geological Survey Flood Fringe. The area within the floodplain (as de- termined by the reach of the one-percent-probability flood) that is outside the floodway. Flood Hazard Boundary Map (FHBM). An official map of a community, issued or approved by the Federal Emergency Management Agency on which the boundaries of the floodplain and special flood hazard areas have been designated. This map is prepared according to the best flood data available at the time of its preparation, and is superseded by the Flood Insurance Rate Map after more detailed studies have been completed. Flood Insurance Rate Map (FIRM). An official map of a community, issued or approved by the Federal Insurance Administration, that delineates both the special hazard areas and the risk premium zones ap- plicable to the community. Flood Insurance Study (FIS). A study, funded by the Federal Insurance Administration and carried out by any of a variety of agencies and consultants, to de- lineate the special flood hazard areas, base flood ele- vations, and NFIP actuarial insurance rate zones. The study is based on detailed site surveys and analysis of site-specific hydrologic characteristics. Floodplain. Any normally dry land area that is suscep- tible to being inundated by water from any natural source. This area is usually low land adjacent to a river, stream, watercourse, ocean, or lake. Floodplain Management. The operation of a pro- gram of corrective and preventive measures for re~ ducing flood damage, including but not limited to flood control projects, floodplain land use regula- tions, floodproofing of buildings, and emergency preparedness plans. Flood Proffie. A graph showing the relationship of water surface elevation to a specific location, the lat~ ter generally expressed as distance above the mouth of a stream of water flowing in an open channel. It is generally drawn to show surface elevation for the crest of a specific magnitude of flooding, but may be prepared for conditions at any given time or stage. FIoodproofing. Any combination of structural pro- visions and/or other modifications incorporated into individual buildings or properties primarily for the purpose of reducing or eliminating flood damages. 75