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MECKLENBURG COUNTY FLOOD <br />HAZARD ANALYSIS <br />Mecklenburg County, including the city of <br />Charlotte, wanted its citizens to be aware of <br />their exposure to flooding. In t999, they <br />invested federal, state, and local funds in <br />updatin~ their flood maps. The new maps <br />show not only where the floodplain is cur- <br />rentty but also where it wit| be when the area <br />is completely developed. <br /> To replace its out-of-date floodplain maps, <br />which FEMA created in t975 using predicted <br />1995 [and use, the county used hydrologic/ <br />hydr~uihc':omputer models to develop new <br />maps based on current (~999) land-use and <br />watershe~data. These maps became the <br />cial FEMA Rood insurance Rate Maps (REMs). <br />FEMA, however, does not draw floodplain maps <br />based on future [and use. The county therefore <br />used bui[dout anatysis to prepare focal <br />Roodp[ain Land Use Maps (FLUMS) to Emit new <br />development in the future flood hazard area. <br /> County planners dedved ultimate bui[dout <br /> from local distdct plans to create Gig coverages <br /> of futura land use. The? added these into the <br /> hybrolo~ic/hydrauiic computer models and <br /> computed new flood elevations and floodplain <br /> areas. They then prepared revised zoning and <br /> stream setback regulations to ensure the safety <br /> of future development, including a minimum <br /> base flood e~evat[on, or "freeboard," of one foot <br /> above the projected future flood height. <br /> in order to build community support for <br /> adopting the Future Conditions Roodpiain <br /> maps and new regulations, the county <br /> decided to quantify the benefits of the new <br /> approach in terms of potential flood losses <br /> avoided, in zooo. the county hired a consuJt- <br /> )n~ team to use the HAZUS Rood Loss <br /> Estimation Methodology to compare estimates <br /> <br />of potential flood damage under the new <br />FEMA maps and Ihe FLUMs, <br /> <br />sis found that using the new maps and regu- <br /> <br />and str~c~ures of up to $333 million. These <br />appear in Rgure 2 on page 4. <br /> <br />The first run cambined current land use <br />and the t975 floodplain.'lt calculated a <br />potenda[ loss of about $213 million. <br /> <br />use with the FEMA Year aooo Roodpiain, <br />It calculated a loss of about $3t8 million. <br /> <br />The third run combined the land use at <br />buddout and the Year 2000 Roodpiain. It <br />calculated a loss of about $65t million. <br /> <br /> The difference of some $333 million <br />between the second and third runs persuaded <br />the total leaders that it would be wise to <br /> <br />ZONING PRACTICE 3.06 <br /> <br /> <br />