Res 2018-025/adopting the 2018 Hays County, Texas Hazard Mitigation Plan as the official plan of the City; authorizing the inclusion of the City of San Marcos Hazard Mitigation Plan as an appendix; designating the City Manager as the official authorized

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Floods Floods: Description According to the 2013 State of Texas Hazard Mitigation Plan Update, floods are defined as the accumulation of water within a water body and the overflow of excess water into adjacent floodplain lands. If the local basin drainage area is relatively flat, shallow, or slow-moving, floods can last for days. The floodplain is the land adjacent of a river, stream, lake, or other water body that is susceptible to flooding. In drainage areas with substantial slope, or where the channel is narrow and confined, rapidly moving and extreme high water conditions, called a flash flood, can occur quickly. Floods: Extent Scale Risk Assessment FEMA has developed flood zone categories showing the potential flood extent, as seen in Table 2.24. (Details Damage Indicator Linked) Zone ASpecial Flood Hazard Area (SFHA) subject to inundation by the 1-percent-annual-chance flood event, generally determined using approximate methodologies. Because detailed hydraulic analyses have not been performed, no Base Flood Elevations (BFEs) or flood depths are shown. Zone AESFHA subject to inundation by the 1-percent-annual-chance flood event determined by detailed methods. Base Flood Elevations (BFEs) are shown. Zone AHSFHA subject to inundation by 1-percent-annual-chance shallow flooding (usually areas of ponding), where average depths are between one and three feet. Base Flood Elevations (BFEs) derived from detailed hydraulic analyses are shown in this zone. Zone AOSFHA subject to inundation by 1-percent-annual-chance shallow flooding (usually sheet flow on sloping terrain), where average depths are between one and three feet. Average flood depths derived from detailed hydraulic analyses are shown in this zone. Zone VSFHA along coasts subject to inundation by the 1-percent-annual-chance flood event with additional hazards associated with storm-induced waves. Because detailed hydraulic analyses have not been performed, no Base Flood Elevations (BFEs) or flood depths are shown. Zone VESFHA subject to inundation by the 1-percent-annual-chance flood event, with additional hazards due to storm-induced velocity wave action. Base Flood Elevations (BFEs) derived from detailed hydraulic analyses are shown. (FEMA, 2017) Jurisdiction-specific data for location, previous occurrences, extent, probability, impact, and vulnerability are found in jurisdiction annexes. 54