2019_KittitasCountyHMP_Volume 1_For Adoption

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CHAPTER 6. IDENTIFIED HAZARDS OF CONCERN AND RISK ASSESSMENT METHODOLOGY 6-4 The version used for this plan was Hazus 3.2, released by FEMA in October 2016. Levels of Detail for Evaluation Hazus provides default data for inventory, vulnerability and hazards; this default data can be supplemented with local data to provide a more refined analysis. The model can carry out three levels of analysis, depending on the format and level of detail of information about the planning area: • Level 1—All of the information needed to produce an estimate of losses is included in the software’s default data. This data is derived from national databases and describes in general terms the characteristic parameters of the planning area. • Level 2—More accurate estimates of losses require more detailed information about the planning area. To produce Level 2 estimates of losses, detailed information is required about local geology, hydrology, hydraulics and building inventory, as well as data about utilities and critical facilities. This information is needed in a GIS format. • Level 3—This level of analysis generates the most accurate estimate of losses. It requires detailed engineering and geotechnical information to customize it for the planning area. Application for This Plan The following methods were used to assess specific hazards for this plan: • Flood—A Level 2 User Defined Facility (Flood) analysis was performed. GIS building and assessor data (replacement cost values and detailed structure information) were loaded into Hazus. An updated inventory was used in place of the Hazus defaults for essential facilities. Preliminary Kittitas County Flood Insurance Rate Maps (FIRMs) were used to delineate flood hazard areas and estimate potential losses from the 0.2-, 1-, 2-, 4-, and 10-percent annual change flood events (where flood depth grids were available). Where available, flood depth grids were integrated into the model and vulnerability numbers were generated in Hazus. Where flood depth grids were unavailable, an exposure analysis was performed to identify structures exposed to flood risk. • Earthquake—A Level 2 Advanced Engineering Building Module (AEBM) analysis was performed to assess earthquake risk and exposure. Earthquake shake maps and probabilistic data prepared by Kittitas County and the U.S. Geological Survey (USGS) were used for the analysis of this hazard. An updated general building stock inventory was developed using replacement cost values and detailed structure information from assessor tables. An updated inventory of essential facilities was used in place of the Hazus defaults. Five scenario events were modeled: – Magnitude-6.8 event on the Cle Elum Fault – Magnitude-7.1 event on the Horse Heavens Fault – Magnitude-7.1 on the Mill Creek Fault – Magnitude-7.4 on the Rattlesnake Wallula Fault – Magnitude-7.4 event on the Saddle Mountain Fault 6.4.2 Dam Failure, Landslide, Severe Weather, Volcano and Wildfire For some of the hazards evaluated in this risk assessment, historical data was not adequate to model future losses. However, exposure analysis can be performed if geographic information is available on the locations of the hazards and building inventories. An exposure assessment was performed by intersecting structures