(A) Flood losses resulting from periodic inundation. Flood hazard areas of the city are subject to inundation which results in loss of life or property, health and safety hazards, disruption of commerce and governmental services, extraordinary public expenditures for flood protection and relief, and impairment of the tax base, all of which adversely affect the public health, safety and general welfare.
(B) General causes of these flood losses. These flood losses are caused by:
(1) The cumulative effect of obstruction in floodways causing increases in flood heights and velocities;
(2) The occupancy of flood areas by uses vulnerable to floods or hazardous to others which are inadequately elevated or otherwise protected from flood damages.
(C) Methods used to analyze flood hazards. This chapter uses a reasonable method of analyzing flood hazards which consists of a series of interrelated steps.
(1) Selection of a base flood which is based upon engineering calculations which permit a consideration of such flood factors as its expected frequency of occurrence, the area inundated and the depth of inundation. The base flood selected for this chapter is representative of large floods which are reasonably characteristic of what can be expected to occur on the particular streams subject to the chapter. It is in the general order of a flood which could be expected to have a 1% chance of occurrence in any one year, as delineated by applicable Flood Insurance Studies and the Federal Emergency Management Administration's Flood Insurance Rate Maps and Flood Boundary and Floodway Map, effective on November 26, 2010, or any subsequent effective Flood Insurance Studies, Rate Maps, and Flood Boundary and Floodway Maps issued after the effective date of this section and adopted by the city.
(2) Calculation of water surface profiles based upon a hydraulic engineering analysis of the capacity of the stream channel and overbank areas to convey the base flood.
(3) Computation of the floodway required to convey this flood without increasing flood heights more than one foot at any point.
(4) Delineation of floodway encroachment lines within which no obstruction is permitted which would cause any increase in flood height.
(5) Delineation of floodway fringe, i.e., that area outside the floodway encroachment lines but which still is subject to inundation by the base flood.
(Ord. 2007-O-017, passed 5-7-07; Am. Ord. 2010-O-014, passed 11-1-10)