Hazard Vulnerability Assessment

Flooding: 

General information index. Also see current hazard mitigation measures. Also see Alexander County and Taylorsville flood plain maps (FIRMs)

Alexander County, Hiddenite, Stony Point and Taylorsville have all experienced the effects of flooding. Fortunately there are only a handful of areas that are subject to routine, repetitive, flash flooding and in these areas there are no known residential or commercial structures at this time.

These were the headlines shortly after Hurricane Floyd struck North Carolina. Flooding in North Carolina can be devastating.

To examine its vulnerability to flooding and make an appropriate assessment, the county and the municipality choose several sources for information. One is the HAZUS program offered by FEMA. HAZUS provides a computer model whereby certain data can be obtained based on local conditions. The flood loss estimation methodology consists of two basic analytical processes: flood hazard analysis and flood loss estimation analysis. In the hazard analysis module, characteristics such as frequency, discharge, and ground elevation are used to estimate flood depth, flood elevation, and velocity. In the loss estimation module, physical damage and economic loss is calculated based on the results of the hazard analysis. The results are displayed using a series of reports. Another method was to examine currently available FIRMs (Flood Insurance Rate Maps) also provided by FEMA. These FIRMs have been placed as a layer upon the Alexander County GIS system and were instrumental in the development of the number of structures likely to be affected. This floodplain layer was then used to input data into the damages model. The results are listed below.

For the purposes of planning, the vulnerability assessment to this hazard used Alexander County GIS and the contour layer. Using this system allowed access to a foot print of every structure currently on maps and currently located in the floodplain. To be of maximum benefit to Alexander County it was felt that listing structures by road name would be best. Emergency services may then use this information to enhance warning systems of persons in affected areas. Enhancement of that warning system, however, is not part of this analysis. There may be overlaps in population because a number of these waterways merge at various points. Also many creeks empty into or become part of the Catawba River. Catawba River levels are controlled by dams and flood gates. Therefore high water flooding in these areas is unlikely. Still, they are considered as having a potential threat from flooding. The majority (approximately 73%) of structures and population that could potentially be effected fall into this category. Digital images of the Alexander County 100 year flood plain and Taylorsville 100 year flood plain are available. FEMA Flood Insurance Rate Maps (FIRMs) are available from FEMA, Alexander County Emergency Management and the Alexander County Planning Department. New floodplain maps are expected to be produced by FEMA and North Carolina Emergency Management within the next 24 months which may enhance this assessment. Alexander County's  NFIP participation number is 370398. Taylorsville does not currently participate in the NFIP, but may chose to do so in the future.

There are no known critical facilities in either the 100 or 500 year flood plain in the county or the Town of Taylorsville! The Town of Taylorsville however does experience localized flooding in three areas of concern. These areas of concern, while not within the currently mapped floodplain, are known to local officials and residents. Heavy rains for periods of 24 to 48 hours appear to cause certain drainage problems along a tributary of Muddy Creek. No loss or repetitive loss has occurred to date. These "special concern" areas are a goal of the Town to mitigate. See mitigation Implementation for the specific goal. These "special concern" areas in Taylorsville are:

Table SC1

There may be X Zones included in the estimates below. Elevation, discharge, and flow were not calculated and location information was extrapolated only from within the boundary of the 100 year flood plain. The following are maximum numbers for planning purposes and analysis only.

Structural counts listed below are approximate and based upon a manual count of structures in the floodplain using the Alexander County GIS system. It was often difficult to determine if the structure was a habitable structure or large outbuilding. Address information could not be obtained at this time. Of the structures analyzed approximately 92% were along the Catawba River below Oxford Dam. There were no habitable structures in the Town of Taylorsville listed or located on current FIRMS within the SFHA (Special Flood Hazard Area) and no indications that  development had occurred. Examination of proposed development in Taylorsville gives no indication that any habitable structures are likely to be built in the SFHA in the future. 

Table F1

Table F2

* Damage estimates that may result from a catastrophic 100 year flood event:

* Source - HAZUS - Mathematical calculation based on 100% of all property effected (25% structural, 25% contents) N/A indicates the data was not available or not calculated.