Risk Assessment
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3 RISK ASSESSMENT 3 Risk Assessment ......................................................................................................................................... 3.1 3.1 Hazard Identification ................................................................................................................................. 3.3 3.1.1 Review of Existing Mitigation Plans ...................................................................................................... 3.3 3.1.2 Review Disaster Declaration History ..................................................................................................... 3.5 3.1.3 Research Additional Sources ................................................................................................................ 3.6 3.1.4 Hazards Identified ................................................................................................................................. 3.7 3.1.5 Multi-Jurisdictional Risk Assessment .................................................................................................... 3.9 3.1.6 Hazard Scoring Methodology ............................................................................................................. 3.10 3.2 Assets at Risk ........................................................................................................................................... 3.12 3.2.1 Total Exposure of Population and Structures ..................................................................................... 3.12 3.2.2 Critical and Essential Facilities and Infrastructure .............................................................................. 3.16 3.2.3 Other Assets ........................................................................................................................................ 3.20 3.3 Development Since 2011 Plan Update .................................................................................................... 3.22 3.4 Future Land Use and Development ......................................................................................................... 3.25 3.5 Hazard Profiles and Vulnerability ............................................................................................................ 3.32 3.5.1 Dam Failure ......................................................................................................................................... 3.35 3.5.2 Drought ............................................................................................................................................... 3.40 3.5.3 Earthquakes ........................................................................................................................................ 3.48 3.5.4 Expansive Soils .................................................................................................................................... 3.56 3.5.5 Extreme Heat ...................................................................................................................................... 3.59 3.5.6 Flash Flooding ..................................................................................................................................... 3.65 3.5.7 Grass or Wildland Fire ......................................................................................................................... 3.74 3.5.8 Hazardous Materials Incident ............................................................................................................. 3.82 3.5.9 Radiological Incident ........................................................................................................................... 3.92 3.5.10 River Flooding ................................................................................................................................. 3.96 3.5.11 Severe Winter Storm .................................................................................................................... 3.120 3.5.12 Sinkholes....................................................................................................................................... 3.129 3.5.13 Terrorism ...................................................................................................................................... 3.132 3.5.14 Thunderstorm with Lightning and Hail ......................................................................................... 3.138 3.5.15 Tornado/Windstorm..................................................................................................................... 3.147 3.5.16 Transportation Incident ................................................................................................................ 3.161 3.6 Hazard Analysis Summary ..................................................................................................................... 3.169 Cedar County, Iowa 3.1 Multi-jurisdictional Hazard Mitigation Plan Effective January 2016 44 CFR Requirement §201.6(c)(2): [The plan shall include] A risk assessment that provides the factual basis for activities proposed in the strategy to reduce losses from identified hazards. Local risk assessments must provide sufficient information to enable the jurisdiction to identify and prioritize appropriate mitigation actions to reduce losses from identified hazards. The risk assessment process identifies and profiles relevant hazards and assesses the exposure of lives, property, and infrastructure within Cedar County, Iowa to these hazards. The goal of the risk assessment is to estimate the potential loss in the planning area, including loss of life, personal injury, property damage, and economic loss, from a hazard event. The risk assessment process allows communities in the planning area to better understand their potential risk to the identified hazards and provides a framework for developing and prioritizing mitigation actions to reduce risk from future hazard events. The risk assessment for Cedar County and participating jurisdictions followed the methodology described in the 2013 FEMA Local Mitigation planning Handbook, which includes a four-step process: Step 1—Describe Hazards Step 2—Identify Community Assets Step 3—Analyze Risks Step 4—Summarize Vulnerability This chapter is divided into six main parts: Section 3.1 Hazard Identification identifies the hazards that threaten the planning area and the methodology utilized to score or rank the hazards; Section 3.2 Assets at Risk provides the planning area’s total exposure to natural hazards, considering critical facilities and other community assets at risk; Section 3.3 Development Since 2011 Plan Update discusses what changes in development have occurred since the previous Hazard Mitigation Plan; Section 3.4 Future Land Use and Development discusses areas of planned future development; Section 3.5 Hazard Profiles and Vulnerability for each hazard, this section is divided into two parts: 1) Hazard Profile discusses the threat to the planning area, the geographic location/extent at risk, previous occurrences of hazard events, and probability of future occurrence; and 2) Vulnerability Assessment further defines and quantifies populations, buildings, critical facilities, and other community assets at risk to natural hazards; Section 3.6 Hazard Analysis Summary provides a tabular summary of the hazard ranking for each jurisdiction in the planning area. Cedar County, Iowa 3.2 Multi-jurisdictional Hazard Mitigation Plan Effective January 2016 3.1 Hazard Identification Requirement §201.6(c)(2)(i): [The risk assessment shall include a] description of the type…of all natural hazards that can affect the jurisdiction. The 16 hazards identified for this plan update are listed below in alphabetical order Dam Failure* Drought Earthquakes Expansive Soils Extreme Heat Flash Flood Grass/Wildland Fire Hazardous Materials Incident* Radiological Incident* River Flood Severe Winter Storm Sinkholes Terrorism* Thunderstorm/Lightning/Hail Tornado/Windstorm Transportation Incident *denotes hazards added to this plan update that were not included in the 2011 Cedar County Multi-jurisdictional Hazard Mitigation Plan. Sections 3.1.1 through 3.1.3 describe how these hazards were identified for this plan update. 3.1.1 Review of Existing Mitigation Plans Prior to 2011, Hazard Mitigation Planning in Cedar County was accomplished on a jurisdictional basis. In January 2010, the unincorporated county and incorporated municipalities came together to coordinate multi-jurisdictional mitigation planning for the entire Cedar County planning area. This coordinated effort resulted in the Cedar County, Iowa Multi-jurisdictional Hazard Mitigation Plan, approved by FEMA in January 2011. To identify hazards to include in the Risk Assessment update, a comparison was performed of the hazard identification in the 2013 Iowa State Hazard Mitigation Plan, and the 2011 Cedar County Multi-jurisdictional Hazard Mitigation Plan. Table 3.1 provides the details of the comparison. Cedar County, Iowa 3.3 Multi-jurisdictional Hazard Mitigation Plan Effective January 2016 Table 3.1. Hazard Comparison Chart 2013 Iowa State Hazard Mitigation Plan Hazards 2011 Cedar County Hazard Mitigation Plan Hazards River Flooding Flooding (Riverine and Flash) Flash Flood Tornado/Windstorm Tornadoes Severe Thunderstorms (Windstorms/Hailstorms/Thunder Thunderstorm/Lightning/Hail and Lightning) Severe Winter Storm Sever Winter Storm Levee/Dam Failure Not Included Terrorism Not Included Animal/Plant/Crop