(A) Flood losses resulting from periodic inundation. The flood hazard areas of the city are subject to inundation which results in loss of life and 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 the flood losses. These flood losses are caused by:
(1) The cumulative effect of obstructions in floodplains causing increases in flood heights and velocities; and
(2) The occupancy of flood hazard areas by uses vulnerable to floods or hazardous to others, which are inadequately elevated or otherwise unprotected 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 regulatory 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 is selected for this chapter. It is representative of large floods which are reasonably characteristic of what can be expected to occur on the particular streams subject to this 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 on the Federal Insurance Administration’s Flood Insurance Study, and illustrative materials dated 5-3-2011, as amended;
(2) Calculation of water surface profiles based on 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 water surface increase along the floodway profile; and
(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).
(1976 Code, § 14-101) (Ord. 1421, passed 4-18-2011)