Macbeth, and King Richard the Third

• The role of risk assessment in hazard mitigation and climate change adaptation

• Select tools to inventory community assets and conduct a hazard risk assessment

Communities that are resilient to the impact of natural hazards are not built by chance. The decisions we make about how and where to build determine how successful we are at avoiding disasters. This chapter explains how a risk assessment informs us about the hazards we face, so that we can choose the most appropriate hazard mitigation, preparedness, and climate change adaptation strategies in an effort to become more resilient. A risk assessment consists of several different elements, or steps. To conduct a thorough risk assessment, the community must first identify the hazards that could affect that particular jurisdiction. There must then be a determination of how likely these hazards are, as well as their potential intensity and severity. The community must also assess its level of vulnerability to the hazards identified. Assessing vulnerability includes identifying the people and property that could suffer harm, estimating losses in dollar figures, and predicting who or what could be affected in the future. Increasingly, communities are also assessing the added level of risk from climate change, calculating the degree to which natural hazards may be changing in the future. The final step in the risk assessment involves assembling and analyzing the relevant data and information in order to form conclusions as to whether the level of risk the community faces is considered acceptable or unacceptable. Each step in the risk assessment process provides additional information to build a sound fact base upon which the community can develop strategies and policies. When completed, a careful risk assessment allows the community to target hazard mitigation, preparedness, and climate change adaptation efforts where they are most needed.

Risk assessment is the process of defining which hazards could impact a community and describing how these hazards could affect people and property. A risk assessment is often performed as part of a comprehensive hazard mitigation planning process, which uses data obtained during the risk assessment as part of a solid fact base that can help direct and justify mitigation policies and strategies. States, local governments, and Native American tribes are required under the Disaster Mitigation Act of 2000 to prepare an all-hazards mitigation plan to be eligible for certain federal disaster assistance and mitigation funding. The risk assessment is one of the required steps in preparing such a plan. We discuss the mitigation planning process in more detail in Chapter 12.

This chapter describes how a typical risk assessment is carried out and how the information may be put to use for reducing community vulnerability to hazards. We primarily focus on mitigation plans prepared at the local level here. While there are a few different steps for state-level plans, in general the process is similar for all risk assessments. Many of the steps described in this chapter are based on risk assessment procedure as outlined by the FEMA in guidance materials designed to help communities prepare hazard mitigation plans as required by the DMA. Therefore, this chapter closely follows the FEMA publication State and Local Mitigation Planning How-to Guide: Understanding Your Risks: Identifying Hazards and Estimating Losses,¹ as well as the more recently published FEMA Guide, Local Mitigation Planning Handbook.² We also rely on a companion website, called Beyond the Basics,^* that is designed to help local governments prepare hazard mitigation plans with the aid of examples and best practices taken from real-life plans that have been developed around the country.

At the time of this writing, FEMA regulations encourage but do not require local governments to address climate change as part of their hazard mitigation plans. However, we incorporate climate change into the discussion of risk assessment throughout this chapter, with the disclaimer that there is still much to be learned about how climate will affect our risk in the future. What we do know is that, while climate change in and of itself may not be considered a hazard, it will nevertheless continue to change the characteristics of the hazards that currently affect a community.

SELF-CHECK

• Define risk assessment.

• Discuss the purpose of a hazard risk assessment.

• Explain why should climate change be considered when conducting a risk assessment.

Each local community is unique, and no two towns or counties would carry out an identical risk assessment. However, there are certain steps common to all hazard risk assessments, and we will cover those main points in this chapter. Figure 10.1 shows the steps we will describe in the following sections.

The steps of the risk assessment process are applicable to all sorts of hazards. There are some unique aspects of the hazard profiling, asset inventory, and loss estimation steps for human-made hazards, but in general, a similar process to assess risk is used whether the community is dealing with natural hazards, terrorism and other intentional threats, or technological hazards such as hazardous material accidents.

Much of the information gathered during the risk assessment process is best displayed on maps, which illustrate the geographic area that could be affected by various hazards. There are many methods for creating hazard assessment maps, ranging from simple traced maps to elaborate computergenerated products. Both types of maps will illustrate local hazard-prone areas and locate important community features. HAZUS (Hazards U.S.) is a computer modeling system that can also be helpful in creating maps and gathering and analyzing data for many of the steps in the risk assessment process. HAZUS was originally developed by FEMA to estimate losses from earthquakes. The latest version—HAZUS-MH (Multi-Hazard)—is used to estimate losses from earthquake, hurricanes, and flooding. The software also contains useful information for preparing inventories and mapping community features vulnerable to other hazards as well.

Figure 10.2 GIS makes it possible to overlay hazards with other characteristics of the community. Tulsa, Oklahoma produced this map to display the areas of highest concern for wildfire on a map of the planning area.

Geographic information systems (GIS) is software that can be used on a computer by users with varying degrees of skill and training and at varying levels of sophistication, from basic applications to sophisticated analysis. In essence, GIS capitalizes on the fact that everything on earth has a unique location (a specific address) in space, allowing the user to create layers of spatial data and superimpose them on one another. For example, maps that show where residential structures are located in a community can be overlaid with flood maps, thus illustrating the relationship between the two layers. The GIS software captures this spatial information, helping us visualize correlations, analyze relationships, and identify patterns over time and space. This information can then be leveraged to formulate conclusions and make decisions about local land use conditions (Figure 10.2).

It is important to remember during the data gathering stage that the quality of the information source directly affects the quality of the assessment and its results. However, raw data that is not entirely accurate or complete should not prevent a community from carrying out a useful risk assessment. FEMA requires that local and state governments use “best available data,” a phrase which reflects the fact that very rarely does a community have access to perfect information. Plan developers should always make note of the source of the data used, its date, and any other metadata that could indicate potential errors, gaps, inaccuracies, or other imperfections. The end results of any data analysis, including (or especially) an assessment of hazard risk should always be viewed with a critical eye that acknowledges possible flaws. This is true for all natural hazards, including data that deals with climate change, which typically is generated at a much larger scale—such as an entire state or region—rather than at a finer grained community level.

USING THE KNOWLEDGE OF INDIGENOUS POPULATIONS TO ASSESS CLIMATE CHANGE RISKS³

Often on the forefront of impacts, indigenous tribes in the United States are frequently cited for their vulnerability to climate change. The Swinomish tribe in Washington State is combining traditional environmental knowledge with modern-day science—including maps of locally specific relative sea level rise scenarios—to assess their risks to climate impacts. In 2007, the Swinomish became the first tribal nation to pass a climate change proclamation, spurred on by first-hand experience of changing conditions on tribal land. The catalyst for the Swinomish tribe came in 2006, when a strong surge from a winter storm pushed logs across a road and into the yards of a number of homes. The tribe considered what the future would look like with a few more feet of sea level rise, and decided that tribal economic development projects that were being planned at the time should not be located in low-lying areas that would be under water in the next 100 years.

Tribes often have good insight into how conditions change over time. They’ve lived in places hundreds and sometimes thousands of years and have seen extremes and learned how to live in those places. Because of their intimate connection to the environment, many tribes are seeing the changes that are happening.

“Very few people have lived in a place long enough within a community to know what’s normal and what isn’t normal, what’s changed and what hasn’t changed.” The tribes retain generations of individual and community knowledge that goes back before humankind started rearranging rivers and reshaping landscapes.

To read the Swinomish climate change proclamation and action plan, go to www.swinomish-nsn.gov/climate_change/climate_main.html.

Hazard mapping begins with a base map, upon which hazard-specific information can be superimposed. A base map shows the basic topography, physical elements, and infrastructure of the community. A good base map for hazard assessment purposes will include political boundaries, such as city limits, extraterritorial jurisdiction, and ownership patterns (i.e., public and private land); roads, bridges, rail lines; water features, including rivers, streams, and watershed; and other natural features such as wetlands, beaches, and steep slopes. The base map should also indicate where development is currently located, as well as the location of infrastructure, such as water and sewer lines, that is scheduled to be laid in the future. The majority of these features can be found on local and state highway maps, local land use and zoning maps, in capital improvement plans, and from aerial photography.

SELF-CHECK

• List the steps in the risk assessment process.

• Describe HAZUS-MH and GIS.

Once a base map is established, the risk assessment can in earnest. The first step in the risk assessment process asks the question: “What kinds of hazards can affect the community?” Hazard identification involves listing all the hazards that might occur in the local region and providing a description of each one. Some hazards occur quite infrequently, while others are regularly recurring events in a community. Even very large hazard events may occur in rapid succession. For example, during the 2004 hurricane season, Florida experienced four major hurricanes within the span of a few weeks. The hurricane season of 2005 saw a similar rapid sequence of huge coastal storms, including Hurricanes Katrina, Rita, and Wilma. Hazard identification involves researching all potential hazards and including them in a list of possible events.

Some hazards may be chronic (regularly occurring but not causing extensive damage each time). These repetitive occurrences can lead to a cumulative impact over time, such as flooding or landslides that can result from numerous rainfalls of average amount. Other hazards may be less regular, but can have more catastrophic impacts when they do occur, such as large hurricanes and earthquakes. The risk assessment should address both chronic and episodic hazards.

There is a wide variety of information sources for hazard identification. Research into the community’s past can indicate the types of hazards that typically occur in the local area. Newspapers, weather reports, past disaster declarations and other historical records from community archives can contain a treasure trove of information. Interviews of long-time residents can also be a good source of information about the types of hazards that have struck the community in the past.

Collecting old accounts of hazard events will provide an overview of the major hazards in the area, but contacts should be widened in order to obtain information about all the possible hazards, not just the “big ones” that community members easily recall or that made major headlines at the time. Local plans and documents that are publicly available often contain information about hazards, even though hazards might not be the focus of these documents. For example, transportation, environmental, or public works reports could have references to local hazard possibilities. Local comprehensive plans, land use plans, and building codes and regulations often contain information about hazards as well. Personnel in local departments may also be able to provide information about hazards that are likely in the area. Police, fire, rescue, and emergency management workers who deal with emergencies on a regular basis are also familiar with hazard possibilities.

The search for information about potential hazards should be expanded beyond local sources. Some hazards are more common in large regions of the country or throughout the state, and these regional hazard possibilities should be included in the hazard identification as well. For example, communities located in “tornado alley” in the Midwest will likely experience more tornadoes in any given year than other parts of the United States. The assumption is simply based on the fact that tornadoes have often impacted that area in the past. State and federal agencies have databanks and other records of hazards on a county or regional level. Many government agencies maintain hazard-specific websites, including state emergency management offices, NOAA, FEMA, USGS, the National Hurricane Center, the National Weather Service, and others.

Terrorist attacks and technological disasters occur infrequently enough in the United States that there may be few relevant records that can help determine what human-made hazards could affect a local community. The Department of Homeland Security, the FBI and the U.S. Department of State issue annual reports on terrorism activity domestically and around the world. State emergency agencies and environmental resource departments, as well as the U.S. EPA are sources for data on hazardous material incidents. Also, in many communities, plans are in place to respond to numerous types of technological hazards, and these plans—and the people who develop them—may be valuable sources of information about human-induced risks. Such plans include emergency operations plans, chemical stockpile contingency plans, toxic release inventory reports, community right-to-know reports, local emergency planning committee files, and other types of emergency and notification documents.

DISASTER EXPERIENCE IN ROSEVILLE, CALIFORNIA INFORMS MITIGATION PLAN

In April 1973, a train en route to the Concord Naval Weapons Station caught fire, detonating more than 6000 bombs. The blast released an enormous chemical-plume, injured more than 350 people, and damaged 5500 buildings. Based in part on this history, the Roseville Hazard Mitigation Plan ranks human-caused events as a top hazard, in addition to flooding. Roseville is recognized as a leader in promoting long-term disaster resilience, using the Hazard Mitigation Plan, as well as its general plan to reduce risks associated with natural and human-caused hazards.

SELF-CHECK

• Define hazard identification.

• List sources of information for identifying potential natural hazard events.

• List sources of information for identifying potential human-made hazard events.

A hazard profile asks the question: “what is the potential impact of the identified hazards on the community?” The hazard profile helps determine how each hazard will affect the community, how often each hazard may occur, and where the hazards might take place. It is important to ascertain whether the hazards the community has identified are cyclical, seasonal, or whether they can happen at any time. It is also important to know the location and geographic extent of each hazard type. Certain portions of the community will be affected on a regular basis in identifiable areas, such as floodplains surrounding streams and rivers. Other types of hazards, such as earthquakes or snowstorms, will affect the entire community. Hazards of various intensities will also affect the community in different ways. For example, a tornado that ranks 4 or 5 on the Enhanced Fujita scale would probably cause more damage than a class 1 or 2 tornado. This is important information for the hazard profile. The effects of climate change on natural hazards adds a layer of complexity to a hazard profile, but this complexity should not stop communities from addressing the potential impacts of climate change on the hazards the community already faces.

A good way to begin the hazard profile is to provide information on past occurrences of each hazard. These hazard histories can provide a snapshot of specific events from which we can make some general assumptions about future hazard events based on patterns and trends. A community that has experienced a tornado in the past might assume that another could occur. On the other hand, the fact that a community has experienced an average of three tornadoes each year for the last 30 years does not mean that a tornado will hit any particular point in the locality in the following year. It is clear that there are limitations to using historical data to estimate events that are likely to occur in the future. Nevertheless, a hazard history can provide a good sense of what lies within the range of possibilities. Sources of information of past occurrences are often the same as the sources used to create the hazard identification list in the previous step, such as archived news accounts, weather records, and interviews with local residents and community officials. The hazard history developed during the profile step elaborates on the list, and paints a more complete picture of how historical events have affected the community.

“KNOW YOUR LINE: BE FLOOD AWARE”

The “Know Your Line: Be Flood Aware” High Water Mark initiative, created by FEMA and seven other Federal agencies, helps communities remind residents of major local floods and encourage residents to prepare for the next one. Participating communities post high water mark signs in prominent places, hold a special launch event to unveil the signs, and conduct ongoing education to build local awareness of flood risk and motivate people to take action (Figure 10.3).

FIGURE 10.3 Signs that show the high water mark can help residents visualize the depth of past flood events. The first of more than a dozen high water marks in Nashville, Tennessee was unveiled in 2013 as part of the “Know Your Line: Be Flood Aware” Initiative. (Photo credit: Lee Roberts.)

The hazard profile must assess the extent of each potential hazard listed during the identification step, which involves identifying the magnitude and intensity. The estimates of hazard extent should be based on local historical evidence and regional data. The potential extent of a hazard may be described using relative terms or the profile may refer to standardized intensity scales. Reliable hazard rating scales include the Saffir–Simpson scale that categorizes hurricanes, the enhanced Fujita rating scale for tornadoes, and the modified Mercalli scale that ranks earthquakes (see descriptions of these rating scales in Chapters 3 and 4). Flood severity is often measured in terms of water depth and velocity. For wildfires, severity can be expressed as fire line intensity (a measure of the rate at which a fire releases heat, or the unit length of the fire line), the rate of fire spread (feet per second), and flame length. For other types of hazards with no formal rating scale, severity may be indicated through general terms, such as mild, moderate, or severe.

Some hazards are more likely to occur in a particular community than others. An estimate of probability, or likelihood of occurrence, is not an actual prediction. Instead, probability is based on regional data and local historical evidence to indicate the frequency of occurrence in the past and likelihood of occurrence in the future. Table 10.2 shows one method for communicating probability, based on frequency of occurrence.

The hazard profile must identify the location—the geographic area—that will be affected by each potential hazard. Some types of hazards occur in fairly predictable areas. For instance, floodplains and steep slopes (where landslides can occur) can be identified and described geographically. Other types of hazards are not site-specific and cannot be geographically defined so readily, such as tornadoes, ice storms, and severe winds. For these types of hazards, the entire community is considered exposed.

The most effective means of identifying the location of potential hazards (for those hazards that can be geographically defined) is to create or obtain a map that shows the hazard boundaries. Many types of hazards are mapped by state and federal agencies and made available to local communities. For instance, FIRMs are provided by FEMA to communities participating in the NFIP. Other commonly mapped hazards include earthquakes, coastal erosion, storm surge inundation areas, wind speed zones, tsunamis, landslides, and wildfires. The U. S. Nuclear Regulatory Commission, which regulates all nuclear power facilities in the country, can provide information about Nuclear Planning Zones, which are safety and evacuation zones delineated around all nuclear power plants.

As we discussed in earlier chapters, changes in climate conditions are leading to shifts in the frequency, duration, intensity, variability, and/or location of many natural hazard events. Risk assessments may be most effective if they consider how hazards are likely to change over time. For example, the Lewes, Delaware Hazard Mitigation Plan includes the following statement that describes the potential impacts of climate change on winter storm events:

Currently there are two climate change impacts that are likely to affect winter storms in Lewes. First, it is believed that precipitation in the winter will become more episodic with it falling in more extreme events. These extremes could exacerbate current winter storms making the overall effects of the storms worse. Additionally, the increase in average temperature will likely cause a reduction in the amount of precipitation falling as snow or ice as that precipitation will likely fall as rain instead. When snow and ice are reduced and the increased episodic precipitation is rain, Lewes could see an increase in inland flooding during winter storm events.

CLIMATE CHANGE RESOURCES TO INFORM RISK ASSESSMENTS

Climate.gov: NOAA launched Climate.gov to serve as a single point-of-entry for NOAA’s climate information, data, products and services. This climate portal provides information about the impacts of climate on nearly every aspect of our lives from agriculture to energy to transportation (climate.gov).

Climate.data.gov: Launched as a pilot phase in 2014, the climate.data. gov website contains a wide range of federal datasets related to climate change. The site contains data and resources related to coastal flooding, food resilience, water and ecosystem vulnerability, human health, and energy infrastructure.

Digital Coast: The Digital Coast website was created to provide tools, trainings, stories from the field, and information that allow users to incorporate updated climate data into coastal management decisions. This includes a Sea Level Rise and Coastal Flooding Impacts Viewer to allow communities to visualize inundation zones on top of other community data so that managers can see what is at risk. Additionally, the Digital Coast’s Social Vulnerability Index (SOVI) measures the social vulnerability of U.S. counties to environmental hazards (csc.noaa.gov/digitalcoast).

U.S. Global Change Research Program: The U.S. Global Change Research Program coordinates and integrates Federal research on changes in the global environment and their implications for society. The Program produces regular assessments of global change, including anticipated regional shifts in climate within the United States and anticipated impacts (globalchange.gov) (Figure 10.4).

FIGURE 10.4 Visualizations and projections of multiple scenarios, including their relative likelihood and the potential impacts of each, can help community leaders and planners make decisions in the face of uncertainty about the future. The National Climate Assessment publishes maps and projections based on multiple scenarios of global greenhouse gas emissions.

A variety of resources available from FEMA, OSHA, and other federal and state agencies provides information about event profiles for both intentional and technological hazards. These profiles include information about the characteristics of human-made hazards, such as the following:

• Application mode: describes the human act or unintended event that causes the hazard (e.g., detonation of an explosive device, rupture of a chemical storage container).

• Duration: the length of time the hazard is present on the target (e.g., the duration of a tornado may be just minutes, but a chemical warfare agent such as mustard gas can persist for days or weeks under the right conditions).

• Dynamic/state characteristics: describes the tendency of the hazard’s effects to either expand, contract, or remain confined (e.g., a cloud of chlorine gas leaking from a storage tank can change location by drifting with the wind and can diminish in danger by dissipating over time).

• Mitigating conditions: characteristics of the target and its physical environment that can reduce the effects of a hazard (e.g., earthen berms can provide protection from bombs, exposure to sunlight can reduce the effectiveness of some biological agents).

• Exacerbating conditions: characteristics that can enhance or magnify the effects of the hazard (e.g., depressions or low areas can trap heavy vapors; obstacles in the street such as parked cars or mailboxes can provide concealment opportunities for explosive devices).

These hazard profiles can provide useful information for assessing the various risks associated with human-made hazards. In addition to details about the various agents’ characteristics, information about the ways in which they can impact the built environment and human populations can help inform decisions about actions that can reduce or eliminate the resulting damage.

At the conclusion of the hazard identification and profile steps, the planning team will have created a map indicating the areas impacted by each hazard type or a report containing information regarding the characteristics of hazard events affecting the community. In some cases, such as those involving flooding, both types of information will be available. The importance of hazard mapping becomes clear during the next step of the risk assessment process, when we inventory community assets and populations.

SELF-CHECK

• Review ways of determining the probability of a hazard.

• Explain what factors determine the extent of a potential hazard.

• List some characteristics of human-made hazards that are important to include in a hazard profile.

Steps one and two of the risk assessment process determine whether a community might experience various types and intensities of hazards, what level of impact those hazards might have, and where within the community those hazards are likely to occur. Step three helps answer the question: “What will be affected by the hazard event?”

During this step the planning team will determine the number of people and amount of existing assets that are at risk from the identified hazards. Assets are all those features of a community that have value, including buildings, facilities (such as wastewater treatment plants), infrastructure (roads, bridges, etc.), historic and cultural landmarks, and other important local resources. Combined with Steps four and five, the community will also be able to estimate losses to assets and determine whether the locality is encouraging or allowing additional development to take place in locations that have been identified as unsafe. The planning team may also identify places where hazard mitigation actions are already being implemented, for example, homes that have been elevated above expected flood heights. In other words, by building on the information gathered during the previous steps, and by following the subsequent steps, the community can gauge its level of vulnerability to hazards, both now and in the future. As always, during the risk assessment process, it is important to remain focused on the ultimate goal—creating and implementing mitigation and preparedness measures that will reduce vulnerability.

To create a complete inventory of assets and populations, we gather and analyze information in three stages or tasks, and compile the information into a spreadsheet, chart, GIS map, or other type of report.

• Task one: Identify assets throughout the community. This community-wide perspective is useful because some types of hazards can affect the entire area, such as earthquakes, ice storms, and tornadoes. It is also useful for indicating the types of land uses that are prevalent in nonhazardous areas of the community, so that if possible, the community can steer future growth and development to these safer areas

• Task two: Review assets and populations that are located in mapped hazard areas

• Task three: Determine what proportion of total community assets are located in known hazard areas. This task indicates what percentage of community assets is vulnerable to hazards as compared to the rest of the community

Sources of information to carry out the asset inventory vary from community to community. Some communities have elaborate data management and GIS capabilities. These communities may also wish to use HAZUS to assist in inventorying assets and populations. Other communities may rely more on local property tax records, subdivision plats, aerial photography and U.S. Census data. Some communities’ emergency 911 systems, especially those that are contained in a GIS format, can also provide valuable information about the location of populations and assets.

The first task in the inventory step involves creating a list and description of assets located throughout the community, identifying each one on a map, and tallying up the total amount of assets. Particularly important to identify are the community’s critical facilities that are necessary for the health and safety of the population, especially following a hazard event. These include hospitals and clinics, police, fire and emergency operations stations, and evacuation centers. Lifeline utilities and other infrastructure should also be listed, including water and sewer systems, communications lines, energy services, as well as major transportation routes. Essential facilities that aid in recovery following a disaster should also be included, such as government and civic buildings, major employers, banks, schools, daycare centers, and certain commercial establishments such as grocery stores, hardware stores, and gas stations. Hazardous materials facilities that manufacture, store, or process industrial/hazardous materials, such as corrosives, explosives, flammable materials, radioactive materials, toxins, and so forth should also be identified. Data from HAZUS, tax records, aerial photography, or local planning documents are useful for gathering this information and displaying it on a map.

GIS, HAZUS, public documents, or tax records can be used to estimate the total value of the buildings and facilities inside each hazard area. The approximate replacement value for each type of building, accessible through local tax assessment records (for privately-owned buildings) and government records (for public buildings and facilities), indicates the cost of rebuilding these structures if they are damaged severely or destroyed by a hazard event. Insurance replacement value is also a good indication of asset value for risk assessment inventory purposes, although these figures may be more difficult to obtain for privately owned structures.

People are your highest priority when inventorying assets. The risk assessment should identify areas of population density as well as the location and number of people with unique vulnerabilities. Whether it’s due to age, disability, poverty, language, mobility, or other barriers, socially vulnerable populations often face greater challenges preparing for, coping with, and recovering from disasters. These populations may also demand a relatively larger deployment of resources such as first responders immediately before, during, and after a disaster.

Table 10.3 shows an example taken from the Hazard Mitigation Plan in King County, Washington where the risk assessment includes a description of vulnerable population groups within the county and the state.

In addition, itinerant populations might also be at greater risk from hazard events. Itinerant populations include students, second homeowners, migrant farm workers, tourists, and visitors for special events such as sporting events and festivals where large numbers of people are concentrated. Visiting populations may be less familiar with the local environment and ill prepared to evacuate or protect themselves.

Task three of the asset inventory involves calculating the proportion of assets and their values that are located in hazard areas as compared to the community total. This task is carried out by dividing the number or value in each hazard area by the total number or value in the community as a whole. For example, if 20 residential structures are located in the community and 10 of those are located in the 100-year floodplain, then 50% of local residential structures are located in the flood hazard area. This is valuable information for gauging overall vulnerability.

By presenting information about the percentage of the building stock (and the community tax base) that is susceptible to hazard damages, we can see “by the numbers” how vulnerable the community is. These figures can serve as a real eye-opener to local officials and citizens, encouraging them to financially and politically support proactive mitigation and preparedness efforts.

Conducting a risk assessment for intentional human-made hazards involves an asset-specific approach to identify the structures and facilities that may be potential targets of a terrorist attack. Each asset is then assessed individually for its particular vulnerabilities. Critical infrastructure and systems that should be inventoried during this step include those whose incapacity or destruction would have a debilitating effect on the defense or economic security of the community, state, region, or nation. These critical infrastructure categories include the following:

The vulnerabilities of these assets can be identified through two basic approaches: inherent vulnerability and tactical vulnerability.

• Inherent vulnerability: The way a building or facility is used, how visible it is, how accessible it is, how many people are located there, and other factors determine that asset’s level of inherent vulnerability. For example, a football stadium or large concert arena are settings where thousands of people gather and where it is relatively easy to gain entry. A terrorist may find such a target attractive because many people could be hurt during an attack. An assessment of such inherent vulnerabilities must be conducted for each asset to determine its weaknesses.

• Tactical vulnerability: The way a building is designed, built, landscaped, and engineered determines its tactical vulnerability. For example, if an HVAC system is designed so that it is not easily accessible and has security cameras aimed at it, a terrorist may be less likely to attempt to use the system as a weapon to release poisonous gas. A tactical vulnerability assessment should be completed for each asset that has been identified as at risk from intentional hazards to determine how well it is protected from attack.

The next step in the vulnerability assessment involves creating map overlays. Hazard maps created during step two of the risk assessment process can be overlaid on the community’s base map to visualize the number and value of buildings and the populations that could be impacted in these areas. Overlay maps that show community features and the ways that hazards can affect these features can be produced using GIS.

As an example, the map in Figure 10.5 indicates where known hazard areas intersect with critical facilities in Morehead City, North Carolina. The risk assessment developed for the community’s Hazard Mitigation Plan identifies critical facilities and hazardous waste sites with an overlay of areas susceptible to flooding.

The fourth step in the risk assessment process answers: “What could the community lose in a hazard event?” So far, the risk assessment has determined that one or more hazards may affect the community (step one), profiled hazard events (step two), and inventoried the assets and populations that could be damaged by a hazard event (step three). In this step, the community estimates losses using dollar amounts that indicate how the community could be impacted economically by the various hazards that threaten it. HAZUS, the loss estimation software produced by FEMA, has been useful to many communities when carrying out this step.

A loss estimate assesses the level of damage that could happen to each individual asset in the inventory from each type of hazard. This involves calculating the losses that could occur to each structure, based on the building’s replacement value in various hazard scenarios. For example, three feet of flood water in a building causes more damage than six inches. The replacement cost of the building’s contents is also added to the calculation. A very detailed loss estimate adds to this the costs incurred when the use and function of each structure is disrupted, for example, if the service provided in that structure must be carried out in an alternative location. When added together, these figures provide an estimated total asset loss for the community.

LOSS ESTIMATE CALCULATION

Structural Loss + Content Loss + Use and Function Loss = Total Loss

The loss estimation step of the risk assessment provides one more piece of information illustrating the community’s level of vulnerability. The ultimate goal is to reduce vulnerability; knowing exactly what is at stake can help develop and target the most appropriate hazard mitigation strategies for achieving that goal.

The costs from a flood, earthquake, or other type of hazard that are captured during the loss estimate are financial in nature. The human losses are much more difficult to calculate. Software products from various state and federal sources can provide credible estimates of the number of people that may be hurt or killed in different types of buildings under different hazard conditions. For the risk assessment it is important to note that the likelihood of people being injured or killed depends upon such factors as warning time, the quality and age of the structures, local response capabilities, and the characteristics of the hazard itself. For some hazards, such as flooding, deaths or injuries are relatively rare in our country, and most often occur when people fail to heed evacuation warnings or when they drive through floodwaters. For other hazards, such as heat waves, injury and loss of life can be widespread. In any event, it is extremely problematic to place a dollar value on human lives; rather, the planning process should incorporate every opportunity to reduce the risk of human injuries and casualties to the greatest extent possible for all sorts of hazards.

SILENT KILLER: HEAT WAVE

Heat is the most deadly weather in the developed world. Every year there are about 700 deaths in the United States due to heat related illness, more than from floods, lightening and tornadoes combined. In the 1980s, two severe heat waves killed up to 20,000 people in the United States. In 1999, a drought and heat wave in the eastern part of the country claimed 502 lives, making it the deadliest weather event of the 1990s. During a heat wave that struck Western Europe in 2003 over 35,000 people were killed by heat related conditions. For comparison, the death toll of Hurricane Katrina was 1836.⁴

SELF-CHECK

• Explain the loss estimate equation.

• Discuss factors involved in estimating potential loss of life from hazards.

So far during the risk assessment process, we have been focusing on the impact a hazard event could have on a community as it exists right now. But communities are constantly changing. As towns and cities grow, their level of vulnerability changes. We might assume that, in general, more assets and more people mean greater vulnerability, and in many cases this is true. Yet we do not have to accept this assumption. Communities can choose to grow and develop in such a way that their vulnerability to hazards does not increase. This does not mean that the hazards will disappear, but it does mean that a community will be conscious of its direction of growth, and will make decisions so that new development is not located in places of danger or is built to better withstand the impacts of hazards. Step five in the risk assessment process evaluates the community’s future vulnerability by asking the question: “What people and property will be at risk from hazards in the future if we continue to grow and develop as we are right now?”

Although there is no sure way to foretell a community’s future, trends in population and land use indicate future directions in growth. The community’s attitude toward new growth is also indicative of future growth trends. These attitudes are articulated through the local ordinances and regulations that control land use in the jurisdiction. During the risk assessment we predict where future development might occur so that if development is being allowed in hazard risk areas, mitigation strategies can be formed to help foster change in the regulatory system.

A good place to start when assessing a community’s potential future vulnerability is to describe all the areas within the county or town limits that are currently undeveloped. Local land use maps, tax data, aerial photography, and even a “windshield tour” of the community can identify empty parcels. For each undeveloped area, the risk assessment includes a description of the dominant form of land cover, such as forest, desert, wetland, farmland, parkland, and so forth.

In addition to describing the current state of undeveloped areas, the risk assessment also describes potential future conditions by considering the types of development that are likely over the course of the next several decades in these undeveloped areas. Most local governments have policies, plans, and regulations that deal with future land uses that dictate what types of new development are allowed. For example, a local comprehensive plan often spells out how and where a community wants to grow over the next 10 or 20 years. Local zoning ordinances and subdivision regulations are usually more specific and describe how many and what type of buildings are allowed in certain areas of the community. These rules and policies provide information about what could be built where, if the rules remain unchanged and if developers and landowners take full advantage of those rules. It is useful to involve the local planner or zoning administrator in this step to get the best information about trends and policies regarding future development. See Chapter 8 for a more detailed discussion of local regulations and land use policies, and how they can be used to reduce future vulnerability.

In addition to looking at the community’s land use plans and zoning regulations to determine the type and location of development that is permissible, the risk assessment should also include a review of local infrastructure plans that show where and when public services will be extended into undeveloped areas, including roads, water lines, sewer lines, schools, and other community facilities. The decision to build large public infrastructure projects is most commonly implemented through a capital improvement plan, a plan that schedules where and when a local government will build its public assets during the next 5–10 years. Some communities use their master or comprehensive plan to describe the overall land use pattern for the community over the next decade.

Scheduled infrastructure is a good predictor of future development because once these services are provided, development will usually soon follow. These items are necessary to support new neighborhoods, shopping centers, factories, office complexes, and other sorts of construction, and they are typically very expensive to build and maintain. Most large-scale development projects rely on hookups to public water and sewer, as well as other public facilities to be viable investments for the developer and builder.

In smaller communities that may not have enacted land use regulations or a formal capital improvement plan, planners and emergency managers can rely on their own judgment about how and where the community is growing and whether there is potential for development to take place in areas that are currently undeveloped. Insight derived from local residents, business owners, elected officials, and local staff can help inform these conjectures about future land use trends. Is the locality considered a bedroom community for a growing city nearby? Are large employers likely to be attracted to the area? Is a major interstate or connector road going to be constructed to which the community will have access? Has the state or local government created tax incentives or other economic development programs to lure business and industry to the area? These and other questions help predict—at least in a general way—the future development potential, and thereby future vulnerability, of the community.

Knowing which areas of the community are undeveloped and which of these areas may be developed in the future provides a basis for determining whether developable portions of the community are located in known hazard areas. This step involves comparing the hazard area descriptions created during step two of the risk assessment process with the descriptions of undeveloped land and scheduled-infrastructure areas created during this step. An overlay of hazard maps onto the community base map is helpful for visualizing this step.

If the overlays indicate that undeveloped lands intersect with hazardous areas, then more specific information about this potential for future vulnerability is necessary. An overlay of the hazard map with the community’s zoning map, for instance, can indicate the types of development that are allowed in hazard areas. If it appears that development will be allowed that could put more people and property in harm’s way, the community may choose to change the rules before a disaster happens.

SELF-CHECK

• Explain why it is important to include anticipated future development in a risk assessment.

• What do capital improvement programs tell you about development trends?

The risk assessment process can provide a wealth of information about the community’s level of vulnerability to a wide range of potential hazards. Much of this information will be in the form of charts, spreadsheets, tables, and reports full of figures and projections, as well as maps that illustrate the locations of community assets in relation to known hazard areas. But the value of this information lies in the conclusions that are formulated—conclusions that are based on the data collected and the analysis conducted.

Each community must look at the risk assessment in its entirety, and decide whether the sum of all the various bits of information put together equal a risk scenario that is either acceptable or unacceptable. In other words, are the problems presented during the risk assessment so great that the community would agree to do something about it? If so, then the level of risk will be considered unacceptable, and the community should then take the necessary steps through hazard mitigation and preparedness to reduce those risks. On the other hand, it might be discovered that only an insignificant portion of the community is actually vulnerable to known hazards, and the community might decide to forgo spending the necessary money, time, and energy in trying to solve its relatively minor hazard problems. The risk assessment may also show that the community already has some mitigation strategies in place; these will factor in to the conclusions as well, perhaps strengthening public resolve to continue risk reduction further. Either way, it is important that the conclusions formed at the end of the risk assessment process are directly tied to the information that was gathered and analyzed.

The conclusions drawn from the risk assessment are not set in stone. Over time, the community’s level of vulnerability may change. For example, a rapid rise in population may call for revisions of the asset and population inventories to make sure incoming residents aren’t placed in an area of risk. On the other hand, overall vulnerability may decline, as mitigation strategies are implemented and risk is reduced. The risk assessment process is not meant to be static, and as local conditions change, the risk assessment will need to be updated and modified to reflect those changing conditions.

OPENING THE EYES OF THE COMMUNITY

Over 30 years ago (before the use of GIS was widespread), the forward-thinking town planner for the Town of Nags Head, North Carolina, made large, oversized maps showing all of the community’s taxable property. The town is located on the Outer Banks of North Carolina, an area that is frequently hit by hurricanes. The planner taped the maps to the wall, and during a town council meeting he took a red pencil and drew a line that marked an area 300 feet landward from the ocean. This line, although only an approximation, represented the area that typically suffers the majority of damage from hurricane winds and storm surge. It also represented the area where the majority of the town’s tax base was located! Despite the fact that few hurricanes had visited the area in the previous decade, the town council, on being graphically informed of the risk they were taking, decided to create one of the first hazard mitigation plans in the region.

If a community decides that its level of risk is unacceptable, the risk assessment can provide a factual basis for creating targeted mitigation strategies. This is often effectively accomplished by developing a mitigation plan, a policy document that lays out goals, objectives, and actions intended to reduce the vulnerabilities highlighted during the risk assessment process. The risk assessment and loss estimations are just one element of a complete hazard mitigation plan, but it is the plan itself that will put measures in action to reduce vulnerability. Through a mitigation plan, we can use the information obtained during the risk assessment to protect existing buildings and to retrofit older buildings against hazard impacts. Where land is not yet developed, we can guide future development and keep people and property out of areas we know are hazardous.

Throughout this chapter, we have tried to emphasize that a risk assessment is not a silver bullet—it cannot predict with certainty that any particular hazard will impact any particular community; this level of uncertainty is especially true when we try to assess how a changing climate will change what we know about hazards. So how do we deal with all this uncertainty? One way is to use the information gleaned from the risk assessment to develop risk reduction policies that will leave us with “no regrets.” In other words, we implement actions that are good for the community regardless of the precise degree of risk involved. These actions often involve multiple participants and fulfill more than one local goal in a win–win for the entire community.

SELF-CHECK

• List ways to incorporate the results of the risk assessment into actions that will reduce vulnerabilities.

• Discuss factors that influence a community’s decision to act on a risk assessment.

• Explain how a risk assessment can be used to steer development away from hazardous areas.

Now that we have described the necessary steps to carry out a thorough risk assessment to serve as part of the foundation for mitigation and preparedness activities, we are ready to begin applying these concepts. In this section, we use a fictitious community named Hazard City to illustrate the risk assessment process. As you read this section, imagine yourself as the emergency manager or planner of this community, so you can visualize going through the steps as both a concerned citizen and as a professional tasked to improve your community’s resiliency to hazards. Read the Hazard City case study below and pause to consider the bulleted questions interspersed in the section. It is our hope that the exaggerated conditions we present will spark ideas about options the community might take, and that you will have a bit of fun while you tackle some serious issues.

Hazard City, nestled in the Mountain-Coastal Territory of Atlantic State, is home to 10,000 residents. It is an area of incredible natural beauty, with steep-sloped mountains covered with pine forests, and a broad, quiet river with gently sloping banks. Nearly 80 years ago, an earthen dam was built across the Lazy River to create a man-made lake, which serves as the source of drinking water for the town. The crown jewel in Hazard City is its wide sand beach that flanks the coast of the Atlantic Ocean, accessible only by a narrow causeway from the mainland. Every summer, hundreds of visitors converge on the oceanfront to attend a three-day music festival.

Hazard City is undergoing tremendous population growth. The investment in public and private infrastructure has been in the millions of dollars for the past five straight years. New schools and shopping centers are being built, and roads, water and sewer lines are being planned for areas not yet developed. The wetlands located near the river are considered particularly desirable for new growth, and are slated to be drained and filled soon, although a local conservation group, however, has identified an endangered species of frog that lives only in the particular habitat provided by the marsh. A chemical plant located on the river bank at the end of a railroad spur has just hired 200 workers, and new subdivisions are springing up to accommodate families moving into the area. Investors are considering building a large hotel on prime beachfront real estate to attract more tourists. Developers, the mayor, and the town’s tax assessor are ecstatic.

Over the years, however, natural hazards such as a cluster of hurricanes in the 1980s, devastating tornadoes in 2009, 2011, and 2014, as well as annual, intense forest fires have impacted local residents, businesses, and the tourism industry. Flooding threatens Hazard City every year, as the river swells its banks with melted snow from the mountains. In 2014, back-to-back snowstorms shut the city down for nearly a week. Power was out for two weeks in some neighborhoods, and roads were impassable for days. Occasionally, mild earthquakes can be felt in the area, although no damage from quakes has been recorded since 1910, when a grain elevator just outside of town was toppled. Periodic landslides have closed some of the mountain roads with rock and debris.

Historically, drought has not been a problem in Hazards City. However, in three of the last five years there was significantly less snowfall in the mountains that the region normally gets, leading to lower water levels in the Hazards City reservoir. Some local environmental groups and the water utility are requesting a study about the potential effects of climate change on the municipal water supply.

By far the single most devastating natural hazard to hit Hazard City in recent memory was Hurricane Zelda in 2013. The scars of Zelda, a powerful Category 3 storm, can still be seen throughout the city. Although the town had survived hurricanes before, the storm surge and flooding seemed particularly high during Zelda. Even the “old timers” who had lived in Hazard City all their lives could not recall waves so high or flooding that reached so far inland. In some neighborhoods, many of the damaged homes have not been fully repaired, where roofs and siding were ripped off by high winds and entire buildings were uprooted. A majority of the town’s small businesses have never reopened. The coastal areas took the brunt of the storm, and numerous oceanfront lots have yet to be redeveloped, while some lots were eroded so severely that very little shorefront remains. However, the homes that were located a few rows back from the oceanfront that had been elevated on stilts above the flood level of the last storm, received relatively minor damage.

The Hazard City town council has just appointed a team to develop a hazard mitigation plan that meets FEMA requirements, so that the town will be eligible for federal disaster assistance—including funds for hazard mitigation projects—when the next disaster strikes. The team, lead jointly by the planning director and the director of emergency management, is about to embark on the risk assessment phase of the mitigation planning process.

• Are there any hazards or secondary impacts not specifically mentioned in the description that could affect Hazard City?

The types of hazards that would be listed in the hazard identification step of the community’s risk assessment include hurricane (with storm surge and erosion), riverine flooding, tornado, forest fire, severe winter storms, earthquake, and landslide. The hazard identification may also include a potential dam break and chemical spill, as well as sea level rise. Of course, in reality, additional sources of information to complete the hazard identification step for Hazard City would be available, including government websites for the region, interviews with residents, a review of local documents and plans, reports of municipal employees, old weather reports and archives, and so forth. In fact, information overload is often experienced when planners and emergency managers begin gathering information about local hazards. It can be difficult to determine when to stop the data gathering stage and move on to the next step in the planning process.

• What potential impact might we expect from each of the hazards identified for Hazard City?

As we mentioned earlier in the chapter, a great place to start with a hazard profile is to explore and document the community’s hazard history. Instead of merely noting each event, details that give us information about the extent, severity, and location of the hazard are particularly helpful. For example, instead of merely mentioning that Hurricane Zelda occurred in 2014, the hazard history for Hazard City should indicate the critical features of Zelda, including wind speeds, depth of flooding, height of storm surge, as well as a description of property damages and the number of deaths and injuries. A complete hazard history would also indicate longer-lasting impacts of a past hazard event, such as whether businesses closed, either permanently or temporarily, whether people were displaced and moved away, whether specific populations within the community were disproportionately affected, and other pertinent facts about how the event affected the local economy, social networks, and the built environment.

Although no single natural hazard event can be attributed to climate change, a discussion of how trends in hazard occurrence are changing could be a helpful part of a comprehensive hazard profile. For example, the fact that Hurricane Zelda’s storm surge, flood levels, and erosion were record-breaking may be indication that conditions are starting to change with regard to sea level rise and the severity of future storms.

The emergency manager of Hazard City has obtained many hazard maps from state and federal agencies, including the town’s FIRM, storm surge inundation maps, erosion rate maps, topographical maps (for steep slope and landslide areas), seismic zone maps, wildfire maps, and a dam inundation map that shows flood potential downstream in the event of a dam break. The community has also chosen to illustrate potential sea level rise along the shoreline, using several scenarios that show a range of projections. By layering all these maps onto the base map, the Hazard City planning team can create a map that defines the boundaries of all the city’s potential hazards.

Since Hazard City takes an all-hazards approach to emergency management, the planning team should include the potential risk from technological hazards in its risk assessment. The existence of a chemical plant on the riverbank could pose such a hazard risk, for instance, if hazardous materials spilled into the river, or an accident occurred during transportation. However, for security purposes, identifying the specific location and contents of the chemical plant and its contents may not be advisable. For extremely volatile industries, states often have secure-access maps, which can only be viewed by authorized personnel. In these communities, decision makers must balance the citizens’ right to know about the hazards in their neighborhood with security concerns.

Table 10.4 indicates the proportion of Hazard City assets and population that are located in the town’s flood hazard area. We can see from the last row in the chart that 40% of Hazard City’s structures and 42% of the town’s property values are located in flood areas. We can also see that 42% of the town’s population lives and works in the flood hazard area. This chart tells us that a very significant percentage of the town’s total property value and many of its people are in danger from flooding.

• What additional information would be useful to know about assets in Hazard City that would help us understand the level of risk?

• Are there certain populations that we may want to know more information about at this stage of the risk assessment?

Now that we have a better sense of the hazards facing Hazard City, as well as the assets and populations that may be exposed to these hazards, it is time to begin estimating potential losses that could occur from various scenarios. For hazards that only occur in some locations, such as flooding that may occur from a hurricane’s storm surge, we may choose to add the value of property located within a certain distance and elevation from the shoreline. For a snowstorm, in addition to damages to structures and infrastructure, we may look at the average length of time it takes the city to clear snow and restore power sufficiently for businesses to reopen. Loss estimate software, such as the FEMA-developed HAZUS, can be invaluable at this stage of the risk assessment.

• How much development should we expect in Hazard City over the coming years, and where will it be located?

• How will changes in the way land is used in Hazard City influence vulnerability to hazards? Is this more pronounced for specific hazards?

This chapter explains how a risk assessment informs us about the hazards we face, so that we can choose the most appropriate mitigation and preparedness strategies in the effort to become more resilient. To begin, a community must identify all the hazards that might occur, information that is largely based on events of the past, as well as other local and regional data. In the second step of the risk assessment process the community creates a profile of the hazards that includes the areas that may be affected, the possible impacts, and the probability of recurrence. The third step involves an inventory of those assets and populations that are vulnerable to hazards. In the fourth step, the community estimates what could be lost in a hazard event, using dollar figures, as well as projected numbers of deaths and injuries. The community uses the fifth step of the process to anticipate future vulnerability by describing growth and development trends. The chapter concludes with a discussion of the sixth step, outlining ways that communities can arrive at conclusions about the acceptable level of risk based on risk assessment findings.

1. The purpose of a risk assessment is to determine what would happen if a hazard event occurred in a community. True or False?

2. Repetitive occurrences of chronic hazards do not lead to a cumulative impact over time. True or False?

3. The risk assessment process for a hurricane greatly differs from that used for hazardous material accidents. True or False?

6. Research into a community’s past hazard events should include major events as well as those that are less significant. True or False?

7. A hazard profile identifies the severity of a potential hazard, in some cases using terms such as mild, moderate, or severe. True or False?

d. A combination of magnitude of event, area affected, and amount of human activity

11. Tactical vulnerability is partly determined by how a facility or building is used. True or False?

12. Potential losses from a man-made hazards area are typically divided into three groups: people, assets, and functions. True or False?

13. Methods to estimate losses from natural hazards work equally well with hazards of a terrorist or technological nature. True or False?

15. An evaluation of a community’s undeveloped areas and their potential for growth helps determine a community’s potential future vulnerability. True or False?

3. Which steps in the risk assessment process help you determine the community’s level of vulnerability?

5. Describe three examples of where to find information about past hazard events.

7. What sources are available to find out about regional climate change impacts?

9. What are the limitations of using historical information to estimate what will happen in the future?

11. The extent of a hazard is identified in the second step of the risk assessment process. Which scale could be used to describe the potential severity of a tornado?

12. Step three of a risk assessment, inventorying vulnerable assets and populations, involves three tasks. Describe each of the three tasks.

13. As part of the inventory process, you must estimate the value of each community asset. Explain how.

14. Two approaches can be used to identify the vulnerability of an asset. Define tactical vulnerability and give an example.

15. What is the name of the risk assessment program used for analyzing potential losses from floods, earthquakes, and hurricane winds?

18. Explain hazard probability for flooding and what a 100-year flood-plain means.

1. What elements of your community’s risk assessment process would you choose to display on maps? Why? What are some of the sources you would use to create your maps?

2. As a planner in Biloxi, Mississippi, you have been charged with carrying out the city’s risk assessment. What role does the risk assessment play in creating the city’s mitigation strategies? Identify the natural hazards that affect your community; determine if any are chronic hazards.

3. In the past eight years, two trains have derailed on the rail line that runs through your community. One was significant, involving a hazardous material and two deaths. Create a hazard profile for this hazard. How does this profile differ from one for a natural hazard?

4. How would you go about determining the level of vulnerability to natural hazards for Lewes, Delaware? What resources, Internet or otherwise, would you go to for the information you needed for the three tasks required for this step?

5. Using the formula provided in the text for calculating estimated total losses, determine the total loss that would result from a hazard event impacting your home or residence. Would that loss vary depending on the hazard? If so, indicate why?

6. As a planner what would you do if you discovered an undeveloped area of your community was vulnerable to landslides? You’ve already read about plans to build a bigger road and bring water and power to this potentially hazardous area.

7. Imagine you live a rural farming community in Ohio. Why is a future project to install water and sewer lines in an area an indicator of future development? What does this tell you about the future vulnerability of this area?

All it takes is a few inches of water to cause major damage to your home and its contents. An interactive tool provided by FloodSmart. gov (a resource of the National Flood Insurance Program) shows you what a flood in your home could cost, inch by inch. When the waters “rise,” the dollar figures mount, as carpets, appliances, electrical outlets, personal belongings, furniture, and other household goods get soaked. The educational site even includes the cost of cleaning. To check out the tool yourself, visit https://www.floodsmart.gov/floodsmart/pages/flooding_flood_risks/the_cost_of_flooding.jsp.

Part of assessing a community’s vulnerability is determining what’s at stake for loss in the future. Describe areas of your town or county that are undeveloped; include their current state as well as their potential future condition. Use resources such as the Internet, aerial maps, tax maps, and local land maps. Whenever possible, indicate who owns the property.

Choose what you think is the most significant natural hazard that threatens your community. Complete a hazard profile, determining the hazard’s extent, probability, and location.

Consider the hazard-prone areas of your community where people live or work. Predict the feasibility of a mitigation plan based on your community and local political attitudes toward growth and mitigation.

1. FEMA. 2001. State and Local Mitigation Planning How-to Guide, Understanding Your Risks: Identifying Hazards and Estimating Losses. Publication 386-2. FEMA.

3. NOAA. 2014. Lessons in resilience: How indigenous tribes are helping lead the way on climate change. Coastal Services (17)2: 11–14.

4. Woodruff, S. C. et al. 2013. Adapting to Climate Change: A Handbook for Local Governments in North Carolina. Chapel Hill, NC: Coastal Hazards Center at the University of North Carolina at Chapel Hill. Available online at coastalhazardscenter.org/adapt.

Level	% Area Affected	Impact
Catastrophic	More than 50%	Multiple deaths Complete shutdown of facilities for 30 days or more. More than 50% of property severely damaged
Critical	25%–50%	Multiple severe injuries Complete shutdown of critical facilities for at least two weeks More than 25% of property severely damaged
Limited	10%–25%	Some injuries Complete shutdown of critical facilities for more than one week More than 10% of property severely damaged
Negligible	Less than 10%	Minor injuries Minimal quality-of-life impact. Shutdown of critical facilities and services for 24 hours or less Less than 10% of property severely damaged

Likelihood	Frequency of Occurrence
Highly likely	Near 100% probability in the next year
Likely	Between 10% and 100% probability in the next 10 years, or at least one chance in the next 10 years
Possible	Between 1% and 10% probability in the next year, or at least one chance in the next 100 years
Unlikely	Less than 1% probability in the next year, or less than one chance in the next 100 years

Asset	Any human-made or natural feature that has value, including, but not limited to people, buildings, infrastructure, critical facilities, and environmental, cultural, and recreational features.
Base map	Graphic that shows the basic topography, physical elements, critical facilities, and infrastructure of a community; can be used to superimpose hazard-specific information for an illustration of vulnerability.
Critical facilities	Facilities critical to the health and welfare of the population, especially following hazard events. Critical facilities include, but are not limited to evacuation shelters, police and fire stations, hospitals, life line infrastructure such as water and sewer treatment facilities, power generation stations, and communication and transportation networks.
Essential facilities	Facilities important for a full recovery of a community following a hazard event. These include government buildings, major employers, banks, schools, and certain commercial establishments such as grocery stores, pharmacies, hardware and building supply stores, and gas stations.
Geographic information systems	A computer software application that relates physical features on the earth to a database to be used for mapping and analysis.
Hazard identification	The process of identifying hazards that threaten an area.
Hazard profile	A description of the physical characteristics of hazards and a determination of various descriptors including magnitude, duration, frequency, probability, and extent.
HAZUS	A risk assessment tool used to estimate hazard losses. HAZUS contains a database of economic, census, building stock, transportation facilities, local geology, and other information.
Inherent vulnerability	Factors such as the way a building or facility is used, how visible it is, how accessible it is, how many people are located there, and other factors that determine the asset’s level of susceptibility, often in reference to intentional man-made hazards.
Lifeline utilities	Services that are essential to a community’s health and well-being, such as potable water, wastewater treatment, power systems, and communication networks.
Loss estimate	A calculation in dollar amounts of the potential damage to structures and contents, interruption of services, and displacement of residents and businesses caused by a hazard.
Magnitude	A measure of the strength of a hazard event, or how much energy is released. The magnitude (also referred to as severity) of a given hazard event is usually determined using technical measures.
Probability	A statistical measure of the likelihood that a hazard event will occur.
Recurrence interval	The time between hazard events of a similar size in a given location. It is based on the probability that the given event will be equaled or exceeded in any given year.
Risk assessment	The process or methodology used to evaluate risk. Risk assessment typically includes five preliminary steps: (1) identify hazards; (2) profile hazard events; (3) inventory assets and populations; (4) estimate losses; (5) determine future development and population trends. A sixth step, (6) determine acceptable level of risk, is often included in a risk assessment to decide whether further action is warranted.
Tactical vulnerability	Factors such as the way a building is designed, built, landscaped, and engineered that determine the asset’s susceptibility to hazard impacts, often in reference to intentional man-made hazards.
Vulnerability	The extent to which people will experience harm and property will be damaged as the result of a hazard. Present vulnerability involves who and what is at risk now; future vulnerability indicates who and what may be at risk in the future under projected development and population trends.