SECTION 4: RISK ASSESSMENT
Probability: 3 – Likely CLIMATE CHANGE
Per the Fifth National Climate Assessment, frequency and intensity of heavy precipitation events is expected to increase across the country. Additionally, increased levels of rainfall, temperatures, sea level rise, and land cover change can exacerbate flood risks and are expected to occur throughout the southeast. Therefore, with more rainfall falling in more intense incidents, the region may experience more frequent flash flooding. Increased flooding may also result from more intense tropical cyclone; researchers have noted the occurrence of more intense storms bringing greater rainfall totals, a trend that is expected to
continue as ocean and air temperatures rise. VULNERABILITY ASSESSMENT
The following section provides an assessment of vulnerability to flooding by jurisdiction and flood return period.
METHODOLOGIES AND ASSUMPTIONS
Population and property at risk to flooding was estimated using data from the NCEM IRISK database, which was compiled in NCEM’s Risk Management Tool. As a subset of the building vulnerability analysis, exposure of pre-FIRM structures was also estimated. Table 4.41 below provides the NFIP entry date for each participating jurisdiction, which was used to determine which buildings were constructed pre-FIRM. Pre-FIRM structures were built prior to the adoption of flood protection building standards and are therefore assumed to be at greater risk to the flood hazard. Table 4.41 – NFIP Entry Dates
Jurisdiction
NFIP Entry Date
City of Raleigh Town of Apex Town of Cary
08/15/78 03/03/92 07/17/78 11/01/78 07/03/78 03/03/92 08/01/78 11/01/78 03/03/92 07/03/78 06/01/78 07/03/78
Town of Fuquay-Varina
Town of Garner
Town of Holly Springs Town of Knightdale Town of Morrisville Town of Rolesville Town of Wake Forest
Town of Wendell Town of Zebulon
Unincorporated Wake County 11/15/78 Source: Federal Emergency Management Agency Community Status Book Report: Communities Participating in the National Flood Program, August 2013 If the NFIP entry date for a given community is between January and June, buildings constructed the same year as the entry date are considered to be post-FIRM (e.g., if the NFIP entry date is 02/01/1991, buildings constructed in 1990 and before are pre-FIRM. Buildings constructed from 1991 to the present are post-FIRM.). If the NFIP entry date is between July and December, then the following year applies for the year built cut-off (e.g., if the NFIP entry date is 12/18/2007, buildings constructed in the year 2007 and before are pre-FIRM, 2008 and newer are post-FIRM).
Wake County, NC Multi-Jurisdictional Hazard Mitigation Plan
WSP June 2024 Page 138
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