How is public infrastructure included in Community Risk information?

Understand how flooding can impact your day to day life when access to public infrastructure is threatened.  

In addition to damaging  residential properties, flooding can impact day to day life within a community, cutting off access to utilities, emergency services, and transportation. As climate change alters the frequency and severity of extreme weather events, deteriorating infrastructure and the communities they serve will be especially vulnerable. For this reason, operational risks to public infrastructure consider risks over a 30-year period.

How is the risk of flooding to public infrastructure determined?

Flood risks are based on the likelihood of flooding, and the annualized expectation of flooding that reaches the building footprint or parcel centroid of each infrastructure facility. The model then uses the average annual expected depth to each infrastructure facility and checks if that depth is higher than the operational risk threshold. When a facility is flooded to the point where it can no longer function as intended, it is considered to have operational risk.These thresholds vary depending on the type of infrastructure in question, as different infrastructural facilities can withstand different depths of flooding while still maintaining some level of functionality. 

For example, hospitals have an operational threshold of 42 inches, while police stations have a functional threshold of 12 inches. The operational threshold of hospitals is higher at 42 inches of flooding because hospitals are often designed to withstand some risk and provide emergency services, especially in the case of a national disaster. If both infrastructures are expected to flood 12 inches in the event of a 100-year flood, this depth of flooding would not exceed a hospital’s operational threshold of 42 inches, but would exceed the 12 inch operational threshold of a police station. If you would like to learn more about the methods used to calculate an area’s Community Risk to flooding please review this article.

Public infrastructure risk in a geographic area is determined based on the percent of structures and the depth of flooding that causes a facility to be flooded at a depth that exceeds the functionality threshold, causing operational risk. The depth at which a certain percent of public infrastructures have operational risk is used to rank the level of risk resulting in a single public risk ranking for a community.

Public infrastructure risk rankings represent risk as Minimal, Minor, Moderate, Major, Severe and Extreme. Minimal risk is a case where no public infrastructures have flood risk. The depth of flooding which causes operational risk for each community level, neighborhood, zip code, city, and county; is then compared to the depth that causes operational risk for similar community levels within a state or across the country. County level public infrastructure risk is ranked based on how their operational risk depth compares to counties across the county. While, neighborhood, zip code, city level public infrastructure risks are ranked based on how their operational risk depth compares to communities within respective states.

What public infrastructure is considered in Community Risk?

Community Risk to public infrastructure includes utilities, emergency services, and transportation. Power stations, wastewater treatment, and hazardous waste sites are considered utilities. Emergency services are made up of fire stations, police stations, and hospitals. Seaports and airports make up transportation. 


  • Power station - Flood risk to electric power plants. This includes the following plant types: hydroelectric dams, fossil fuel (coal, natural gas, or oil), nuclear, solar, wind, geothermal, and biomass. For each plant type all structures and equipment on a given site are grouped together for each individual facility. The operational threshold for power stations is 24 inches.
  • Wastewater treatment - Facilities used to treat industrial wastewater and remove pollutants. Wastewater treatment plants use various processes (physical, chemical and biological) to treat industrial wastewater and remove pollutants. The operational threshold for wastewater treatment facilities is 0 inches.
  • Superfund Site - Sites contaminated by hazardous waste being dumped, exposed in the open, or badly managed. Superfunds include manufacturing facilities, processing plants, landfills and mining sites. The operational threshold for superfund sites is 12 inches.

Emergency services 

  • Fire station - Facilities where fire engines and other equipment of a fire department are housed. Fire stations accommodate functions such as housing, recreation, administration, training, community education, and hazardous materials storage. The data consists of building locations of fire stations, including those on military bases, airports or manufacturing locations. The operational threshold for fire stations is 24 inches.
  • Police station - Law Enforcement agencies that are publicly funded and employ at least one full-time or part-time sworn officer with general arrest powers. The operational threshold for police stations is 12 inches.
  • Hospitals - Facilities in which sick or injured people are given medical or surgical treatment. The operational threshold for hospitals is 42 inches.


  • Seaport - Major U.S. port facilities, including commercial ports, along the U.S. coast, Great Lakes and inland ports. This includes the location of a port’s waterfront facilities, including information on berthing, cranes, transit sheds, grain elevators, marine repair plants, fleeting areas, and docking and storage facilities. The operational threshold for seaports is 12 inches.
  • Airport  - A defined area on land or water that is intended to be used either wholly, or in part, for the arrival; departure and surface movement of aircraft/helicopters. The operational threshold for airports is 12 inches.


Learn more

What data sources are used to determine Community Risk ratings?

How are Community Risk levels determined? 

How to use the Community Risk map overview 

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