ANNEX A: WAKE COUNTY UNINCORPORATED AREAS
A.3.2 Flood Table A.12 details the acreage of unincorporated Wake County’s total area by flood zone on the effective DFIRM. Per this assessment, over 10 percent of the unincorporated area in the County falls within the mapped 1%-annual-chance floodplains. Table A.12 – Flood Zone Acreage in Unincorporated Wake County
Flood Zone
Acreage
Percent of Total (%)
Zone A Zone AE
244.34
0.07
34,276.21 1,923.22 302,007.04 338,450.81
10.13
Zone X (500-year) Zone X Unshaded
0.57
89.23
Total
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Source: FEMA Effective DFIRM; Wake County GIS
Figure A.4 reflects the effective mapped flood hazard zones for Wake County, and Figure A.5 displays the depth of flooding estimated to occur in these areas during the 1%-annual-chance flood. To supplement the IRISK assessment of property at risk from the 1% annual chance flood event in Section 4 and provide a clearer picture of the current property at risk in Unincorporated Wake County, current parcel data was evaluated to identify parcels developed since 2010. Using GIS analysis, parcels developed after 2010 were compared to the boundaries of the 1% annual chance floodplain to identify the exposure of newly developed property to the base flood. In most cases, a parcel was considered exposed to the floodplain if any portion of the parcel was located in the floodplain. This assessment does not evaluate flood impacts or provide damage estimates. However, this summary of development in or near the floodplain since 2010 provides some context to understand the degree to which the IRISK exposure and vulnerability numbers differ from current conditions. Table A.13 provides a summary by land class of parcel development located in the 1% annual chance floodplain from January 2011 to April 2019. Table A.13 – Parcels Developed 2011 or Later and Located in 1% Annual Chance Floodplain
Land Class
Number of Parcels
Sum of Building Value
Acres Greater Than 10 With House
20
$9,213,446
Forestry Industrial
1 1
$777,207
$48,366,843 $46,029,733 $104,387,229
Residential Less Than 10 Acres
118 140
Grand Total
Source: Wake County Open Data; retrieved April 8, 2019; FEMA Effective DFIRM
Table A.14 provides building counts and estimated damages for Critical Infrastructure and Key Resources (CIKR) buildings by sector and flood event in the City of Raleigh. Table A.14 – Critical Facilities Exposed to Flooding, Unincorporated Wake County
Sector
Event
Number of Buildings at Risk
Estimated Damages
100 Year Floodway 100 Year 100 Year Floodway 100 Year Floodway
20
$439,223 $23,765 $86,000 $60,845 $60,845 $586,068 $84,610
Commercial Facilities
1 2 1 1
Government Facilities
Transportation Systems
23
All Categories
2
Wake County Multi-Jurisdictional Hazard Mitigation Plan 2019
294
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