2019_KittitasCountyHMP_Volume 1_For Adoption

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CHAPTER 6. IDENTIFIED HAZARDS OF CONCERN AND RISK ASSESSMENT METHODOLOGY 6-3 6.3. METHODOLOGY The risk assessments in Chapter 7 through Chapter 15 describe the risks associated with each identified hazard of concern. Each chapter describes the hazard, the planning area’s vulnerabilities, and probable event scenarios. The following steps were used to define the risk of each hazard: • Identify and profile each hazard—The following information is given for each hazard: – Geographic areas most affected by the hazard – Event frequency estimates – Severity estimates – Warning time likely to be available for response. • Determine exposure to each hazard—Exposure was determined by overlaying hazard maps with an inventory of structures, facilities, and systems to determine which of them would be exposed to each hazard. • Assess the vulnerability of exposed facilities—Vulnerability of exposed structures and infrastructure was determined by interpreting the probability of occurrence of each event and assessing structures, facilities, and systems that are exposed to each hazard. Tools such as GIS and FEMA’s hazard-modeling program (Hazus) were used to perform this assessment for the flood, dam failure and earthquake hazards. Outputs similar to those from Hazus were generated for other hazards, using maps generated by the Hazus program. 6.4. RISK ASSESSMENT TOOLS 6.4.1 Earthquake and Flood—Hazus Overview In 1997, FEMA developed the standardized Hazards U.S., or Hazus, model to estimate losses caused by earthquakes and identify areas that face the highest risk and potential for loss. Hazus was later expanded into a multi-hazard methodology, with new models for estimating potential losses from hurricanes and floods. Hazus is a GIS-based software program used to support risk assessments, mitigation planning, and emergency planning and response. It provides a wide range of inventory data, such as demographics, building stock, critical facility, transportation and utility lifeline, and multiple models to estimate potential losses from natural disasters. The program maps and displays hazard data and the results of damage and economic loss estimates for buildings and infrastructure. Its advantages include the following: • Provides a consistent methodology for assessing risk across geographic and political entities. • Provides a way to save data so that it can readily be updated as population, inventory, and other factors change and as mitigation-planning efforts evolve. • Facilitates the review of mitigation plans because it helps to ensure that FEMA methodologies are incorporated. • Supports grant applications by calculating benefits using FEMA definitions and terminology. • Produces hazard data and loss estimates that can be used in communication with local stakeholders. • Is administered by the local government and can be used to manage and update a hazard mitigation plan throughout its implementation.