1971 Zoning Ordinance - Laserfiche WebLink

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Section 10.31 the area landward side of the encroachment lines will be ultimately devel- oped in such a way that it will not be available to convey flood flows. The stream channel and adjoining flood plains between these lines will be maintained as open space and will be adequate to convey the regional flood without adversely increasing flood heights. (4) Equal Degree of Encroachment: Is established by considering the effect of encroachments of the hydraulic efficiency of the flood plain along a signi- ficant reach of the'stream. Hydraulic efficiency depends on such factors as the relative orientation of the channel with respect to the floodway, the natural and man -made characteristics of the flood plain, relative ground level on both sides of the stream, the.type of vegetation on both sides of the stream and the resistance of such vegetation to flood flows. In most cases these factors will not result in equal distances or areas between encroachment lines on both sides of the stream. (5) Flood: A temporary rise in stream flow or stage. that results in water over- topping its banks and inundating area adjacent to the channel. (6) Flood Plain: The land,adjacent to a body of water which has been.or may be hereafter covered by flood water including but not limited to the regional flood. (7) Flood way: The channel of a stream and those portions of the flood plain ad- joining the channel that are required to carry and discharge the flood water or flood flows of any river or stream including but not. limited to flood flows associated with the regional flood. (8) Flood Profile: A graph or a longitudinal profile showing the relationship of the water surface elevation of a flood event to location along a stream or river. (9) Flood Proofing: A combination of structural provisions, changes, or ad- justments to properties and structures subject to flooding primarily for the reduction or elimination of flood damages to properties, water and sanitary facilities, structures, and contents of buildings in a flood hazard area. (10) Flood Stage: For purposes of this Section the term is used to mean the height or elevation of a flood as referred to some datum. For other purposes it is commonly used to refer to the elevation at which a stream will overtop its normal stage banks. (11) Ordinary High Water Mark: . The highest point on the bank of a normal stage channel at which the water level has been for a sufficient period of time to leave a definite mark. (12) Reach: A hydraulic engineering term to describe longitudinal segments of a stream or river. A reach will generally include the segment of the flood plain where flood heights are primarily controlled by man -made or natural flood plain obstructions or restrictions. In an urban area, the segment of a stream or river between two consecutive bridge crossings would most likely be a reach. (13) .Regional Flood: The regional flood is a flood determined by the Division of Environmental Protection which is representative of large floods known to have occurred generally in Wisconsin and reasonably characteristic of what can be expected -to occur on a particular stream. The regional flood generally has - 45 -