SECTION 4: RISK ASSESSMENT
4.3
RISK ASSESSMENT METHODOLOGY AND ASSUMPTIONS
The Disaster Mitigation Act of 2000 requires that the HMPC evaluate the risks associated with each of the hazards identified in the planning process. Each hazard was evaluated to determine its probability of future occurrence and potential impact. A vulnerability assessment was conducted for each hazard using either quantitative or qualitative methods depending on the available data, to determine its potential to cause significant human and/or monetary losses. A consequence analysis was also completed for each hazard. Each hazard is profiled in the following format: Hazard Description This section provides a description of the hazard, including discussion of its speed of onset and duration, as well as any secondary effects followed by details specific to the Wake County planning area. Location This section includes information on the hazard ’s physical extent, with mapped boundaries where applicable. Extent This section includes information on the hazard extent in terms of magnitude, describe how the severity of the hazard can be measured. Where available, the most severe event on record used as a frame of reference. Past Occurrences This section contains information on historical events, including the location and consequences of all past events on record within or near the Wake County planning area. Probability of Future Occurrence This section gauges the likelihood of future occurrences based on past events and existing data. The frequency is determined by dividing the number of events observed by the number of years on record and multiplying by 100. This provides the percent chance of the event happening in any given year according to historical occurrence (e.g. 10 winter storm events over a 30-year period equates to a 33 percent chance of experiencing a severe winter storm in any given year). The likelihood of future occurrences is categorized into one of the classifications as follows:
Highly Likely – Near or more than 100 percent chance of occurrence within the next year
Likely – Between 10 and 100 percent chance of occurrence within the next year (recurrence interval of 10 years or less) Possible – Between 1 and 10 percent chance of occurrence within the next year (recurrence interval of 11 to 100 years) Unlikely – Less than 1 percent chance or occurrence within the next 100 years (recurrence interval of greater than every 100 years) Climate Change Where applicable, this section discusses how climate change may or may not influence the risk posed by the hazard on the planning area in the future.
Wake County Multi-Jurisdictional Hazard Mitigation Plan 2019
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