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8 .. . II. GLOSSARY This section defines terms encountered frequently in flood plain managemen . The definitions are simplified to meet the needs of those who are not specialists i the field. More detailed and scientific definitions of these and other terms can be foun in several of the publications listed in the bibliography. . Backwater Effect - The rise in water surface elevation caused by some obstruc ion such as a narrow bridge opening, buildings or fill material that limits the area through hich the water must flow. Also referred to as "heading up", . Base Flood Elevation (BFE) - A term used by the State of Colorado and FEMA 0 indicate the minimum flood elevation to be used by a community as a basis for its flood lain manage- ment regulations; presently required by regulation to be that flood which has a one-percent chance of being equaled or exceeded in any given year. Also known as a 10 -year flqod or one-percent chance flood. . Base Flood Plain - The flood plain that would be inundated by a 100-year (on -percent chance) flood. Basement Floor - The lowest floor level below the main floor of a building. Basin - The total area from which surface runoff is carried away by a drainage ystem. Other comparable terms are "drainage area", "catchment area", and "watershed". . Building Code - Regulations adopted by a governmental body which set forth tandards for the construction of buildings and other structures for the purpose of protecti g the health, safety and general welfare of the public. . C.F.S. - Cubic feet per second. Used to describe the amount of flow passing a given point in a stream channel. One cubic foot per second is equivaent to approximately .5 gallons per second. Channel - A natural or artificial watercourse with definite bed and banks to co fine and con- duct flowing water. . Channel Capacity - The maximum flow which can pass through a channel with ut overflowing the banks. Cross Section - A graph or plot of ground elevation across a stream valley or a portion of it, usually along a line perpendicular to the stream or direction of flow. . Designated Flood Plain - The flood plain boundary delineated by the base flo d elevation after it has been approved by Colorado Water Conservation Board and adop ed by the local community. Designated Floodway - The channel of a stream and that portion of the adjoini g flood plain designated by a regulatory agency to be kept free of further development to provide for unobstructed passage of flood flows. The designated floodway is within the designated flood plain. . Design Flood - Commonly used to mean the magnitude of flood used for desi nand opera- ion of flood control structures or other protective measures. It is sometimes sed to denote the magnitude of flood used in flood plain regulations . Erosion - The process of the gradual wearing away of land masses due to fricti n forces created between flowing water and the ground surface. .