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SECTION 5.1: METHODOLOGY AND TOOLS DMA 2000 Hazard Mitigation Plan – Cayuga County, New York 5.1-1 August 2013 5.1 METHODOLOGY AND TOOLS This section describes the methodology and tools used to support the risk assessment process. Methodology The risk assessment process used for this Plan is consistent with the process and steps presented in FEMA 386-2, State and Local Mitigation Planning How-to-Guide, Understanding Your Risks – Identifying Hazards and Estimating Losses (FEMA, 2001). This process identifies and profiles the hazards of concern and assesses the vulnerability of assets (population, structures, critical facilities and the economy) at risk in the community. A risk assessment provides a foundation for the community’s decision makers to evaluate mitigation measures that can help reduce the impacts of a hazard when one occurs (Section 9 of this plan). Step 1: The first step of the risk assessment process is to identify the hazards of concern. FEMA’s current regulations only require an evaluation of natural hazards. Natural hazards are natural events that threaten lives, property, and many other assets. Often, natural hazards can be predicted, where they tend to occur repeatedly in the same geographical locations because they are related to weather patterns or physical characteristics of an area. Step 2: The next step of the risk assessment is to prepare a profile for each hazard of concern. These profiles assist communities in evaluating and comparing the hazards that can impact their area. Each type of hazard has unique characteristics that vary from event to event. That is, the impacts associated with a specific hazard can vary depending on the magnitude and location of each event (a hazard event is a specific, uninterrupted occurrence of a particular type of hazard). Further, the probability of occurrence of a hazard in a given location impacts the priority assigned to that hazard. Finally, each hazard will impact different communities in different ways, based on geography, local development, population distribution, age of buildings, and mitigation measures already implemented. Steps 3 and 4: To understand risk, a community must evaluate what assets it possesses and which assets are exposed or vulnerable to the identified hazards of concern. Hazard profile information combined with data regarding population, demographics, general building stock, and critical facilities at risk, located in Section 4, prepares the community to develop risk scenarios and estimate potential damages and losses for each hazard. Tools To address the requirements of DMA 2000 and better understand potential vulnerability and losses associated with hazards of concern, Cayuga County used standardized tools, combined with local, state, and federal data and expertise to conduct the risk assessment. Our standardized tools used to support the risk assessment are described below. Hazards U.S. – Multi-Hazard (HAZUS-MH) In 1997, FEMA developed a standardized model for estimating losses caused by earthquakes, known as Hazards U.S. or HAZUS. HAZUS was developed in response to the need for more effective national-, state-, and community-level planning and the need to identify areas that face the highest risk and potential for loss. HAZUS was expanded into a multi-hazard methodology, HAZUS-MH with new models for estimating potential losses from wind (hurricanes) and flood (riverine and coastal) hazards. HAZUS-MH is a Geographic Information System (GIS)-based software tool that applies engineering and scientific risk ---PAGE BREAK--- SECTION 5.1: METHODOLOGY AND TOOLS DMA 2000 Hazard Mitigation Plan – Cayuga County, New York 5.1-2 August 2013 calculations that have been developed by hazard and information technology experts to provide defensible damage and loss estimates. These methodologies are accepted by FEMA and provide a consistent framework for assessing risk across a variety of hazards. The GIS framework also supports the evaluation of hazards and assessment of inventory and loss estimates for these hazards. HAZUS-MH uses GIS technology to produce detailed maps and analytical reports that estimate a community’s direct physical damage to building stock, critical facilities, transportation systems and utility systems. To generate this information, HAZUS-MH uses default HAZUS-MH provided data for inventory, vulnerability, and hazards; this default data can be supplemented with local data to provide a more refined analysis. Damage reports can include induced damage (inundation, fire, threats posed by hazardous materials and debris) and direct economic and social losses (casualties, shelter requirements, and economic impact) depending on the hazard and available local data. HAZUS-MH’s open data architecture can be used to manage community GIS data in a central location. The use of this software also promotes consistency of data output now and in the future and standardization of data collection and storage. The guidance Using HAZUS-MH for Risk Assessment: How-to Guide (FEMA 433) was used to support the application of HAZUS-MH for this risk assessment and plan. More information on HAZUS- MH is available at http://www.fema.gov/plan/prevent/hazus/index.shtm. In general, probabilistic analyses were performed to develop expected/estimated distribution of losses (mean return period losses) for the flood and wind hazards. The probabilistic hazard generates estimates of damage and loss for specified return periods 100- and 500-year). For annualized losses, HAZUS- MH version 2.1 calculates the maximum potential annual dollar loss resulting from various return periods averaged on a "per year" basis. It is the summation of all HAZUS-supplied return periods 10, 50, 100, 200, 500) multiplied by the return period probability (as a weighted calculation). In summary, the estimated cost of a hazard each year is calculated. Custom methodologies in HAZUS-MH version 2.1 (HAZUS-MH) were used to assess potential exposure and losses associated with hazards of concern for Cayuga County: Inventory: The default demographic data in HAZUS-MH 2.1, based on the 2000 U.S. Census, was used for analysis. However, the 2010 U.S. Census data was used to estimate hazard exposure at the municipal level. The default building inventory in HAZUS-MH was updated and replaced with a custom building inventory developed for Cayuga County. The updated building inventory was built using detailed structure-specific assessor data, as well as parcel and structure location information. The critical facility inventory (essential facilities, utilities, transportation features and user-defined facilities) was updated for the flood and wind hazard models. This comprehensive inventory was developed by gathering input from numerous sources including Cayuga County and input from the Planning Committee. Flood: The 1- and 0.2-percent annual chance flood events were examined to evaluate Cayuga County’s risk and vulnerability to the flood hazard. These flood events are generally those considered by planners and evaluated under federal programs such as the NFIP. The HAZUS-MH riverine flood model was used to estimate Cayuga County’s estimated potential losses. For this plan, the default general building stock in HAZUS-MH was updated and replaced with a custom inventory at the structure and aggregate level, as mentioned above. The updated building inventory was incorporated into the HAZUS-MH flood model as individual buildings. Examining risk at the individual building level versus running the model and reporting results at the ---PAGE BREAK--- SECTION 5.1: METHODOLOGY AND TOOLS DMA 2000 Hazard Mitigation Plan – Cayuga County, New York 5.1-3 August 2013 aggregate level provides more accurate potential loss estimates. An updated critical facility inventory was used in place of the HAZUS-MH defaults for essential facilities and utilities. The Cayuga County FEMA DFIRMs dated August 2007 were used to evaluate exposure and determine potential future losses. The terrain was built using the 3-meter grid available from NOAA which was developed based on the 2000 LiDAR of Cayuga County. However, the USGS 10-meter grid was used to supplement where data was missing. The final Digital Elevation Model (DEM) was resampled to 3-meters (10 feet). Depth grids were developed for the 1- and 0.2-percent flood events for Cayuga County. Hurricane/Wind: A HAZUS-MH probabilistic analysis was performed to analyze the wind hazard losses for Cayuga County. The probabilistic hurricane hazard activates a database of thousands of potential storms that have tracks and intensities reflecting the full spectrum of Atlantic hurricanes observed since 1886 and identifies those with tracks associated with Cayuga County. Annualized losses and the 100- and 500-year MRPs were examined for the wind/severe storm hazard. Default demographic data in HAZUS-MH and updated building and critical facility data were used for the analysis. Ground Failure: In an attempt to estimate Cayuga County’s vulnerability to ground failure due to landslides and karst environments, the Geology - Landslide Incidence and Susceptibility and the Engineering Aspects of Karst GIS layers from National Atlas was used to coarsely define the general hazard areas. A total risk exposure analysis was performed to estimate the population, buildings and critical facilities exposed and vulnerable to this hazard. The limitations of this analysis are recognized and are only used to provide a general estimate. Over time additional data will be collected to allow better analysis for this hazard. Other Hazards: HAZUS-MH support was used to evaluate other hazards, as feasible. For many of the hazards evaluated in this risk assessment, historic data are not adequate to model future losses at this time. However, HAZUS-MH can map hazard areas and calculate exposures if geographic information on the locations of the hazards and inventory data are available. For some of the other hazards of concern, areas and inventory susceptible to specific hazards were mapped and exposure was evaluated to help guide mitigation efforts discussed in Section 9. For other hazards, a qualitative analysis was conducted using the best available data and professional judgment. For this risk assessment, the loss estimates, exposure assessments, and hazard-specific vulnerability evaluations rely on the best available data and methodologies. Uncertainties are inherent in any loss estimation methodology and arise in part from incomplete scientific knowledge concerning natural hazards and their effects on the built environment. Uncertainties also result from the following: 1) Approximations and simplifications necessary to conduct such a study 2) Incomplete or dated inventory, demographic, or economic parameter data 3) The unique nature, geographic extent, and severity of each hazard 4) Mitigation measures already employed by Cayuga County and the amount of advance notice residents have to prepare for a specific hazard event These factors can result in a range of uncertainty in loss estimates, possibly by a factor of two or more. Therefore, potential exposure and loss estimates are approximate. These results do not predict precise results and should be used to understand relative risk. Over the long term, Cayuga County will collect additional data to assist in developing refined estimates of vulnerabilities to natural hazards.