Commonly used vocabulary on Flood Factor

Understand the meaning of commonly used terms on Flood Factor.

  • Adaptation (local) - Local flood risk reduction measures, also known as adaptations, are community funded infrastructure, such as levees, sea walls, pumps, or other features designed to mitigate flood risk to a city, community, or geographic area. Only completed adaptation features are included in our model based on our state-by-state research process, and we have worked to include as many projects as possible at this time, however we acknowledge there are more to analyze and include. Most personal adaptation features are not included at this time, such as raised homes.
  • Adaptation (personal) - Personal flood risk reduction measures, also known as adaptation features, include raising your home, installing sump pumps, raising electrical outlets, and other personal flood barriers unique to an individual property. Because these personal capital improvements do not alter a property’s building footprint (with few exceptions, such as relocating a home on a parcel) they are not incorporated into Flood Factor calculations. 
  • Minimal risk - Properties with a less than 0.2% chance of flood water reaching the building on that property for  every year analyzed are considered to have minimal risk or a Flood Factor of 1. However it is still possible for properties with a Flood Factor of 1 to flood, and therefore, they are still considered to be at minimal risk.
  • Substantial risk - Properties with higher Flood Factors have at least a 1% chance of flood water reaching the building or center of an empty lot in a given year. These properties are either more likely to flood, more likely to experience high floods, or both. Properties with higher Flood Factors have at least a 1% chance of flood water reaching the building or center of an empty lot in a given year. These properties are either more likely to flood, more likely to experience high floods, or both.
  • Building footprint - The outline of the building on a parcel. Flood Factor calculates flood risk to that ground-level imprint for each commercial and private property parcel in the contiguous United States. Personal adaptation features, such as stilts that raise a building off the ground, are not accounted for in a parcel’s Flood Factor, because they do not fundamentally alter the location, area, or shape of a building’s footprint.
  • FEMA Zone(s) -  Geographic areas mapped by FEMA and assessed for flood risk based on historic patterns. These zones are used to create Flood Insurance Rate Maps, or FIRMS, which in turn inform insurance pricing and guide flood management regulations.
  • Floodplain - A floodplain is a generally flat area of land next to a river or stream that is naturally subject to flooding. 
  • Flood insurance - Flood insurance is available to homeowners, business owners, and renters throughout the nation, regardless of whether or not they are in a high-risk flood zone. Flood insurance is one of the best ways to protect against financial losses caused by flood events. Flood insurance is mandatory for certain homes in the Special Flood Hazard Area (SFHA). This includes those with a mortgage from a federally-backed or federally-regulated lender in addition to those with a mortgage backed by a federal agency. Those who receive federal assistance for property acquisition, construction, or repairs may find flood insurance is mandatory.
  • Flood model - The First Street Foundation Flood Model is a nationwide, probabilistic flood model that shows the risk of flooding at any location in the contiguous 48 states from rain, rivers, tides, and storm surge. It builds off of decades of peer-reviewed research and forecasts how flood risks will change over time due to changes in the environment.
  • NFIP (National Flood Insurance Program) - Flood insurance is available primarily from the federally-run National Flood Insurance Program (NFIP). To help alleviate the financial devastation caused by flooding, Congress created the National Flood Insurance Program (NFIP). The NFIP enables homeowners, business owners, and renters in participating communities to purchase federally backed flood insurance. This insurance provides an alternative to disaster assistance that provides additional financial assistance to meet the escalating costs of repairing flood damage to buildings.
  • Minimum depth to building - The minimum depth of floodwater that a building may receive in the event of a flood. The depth of flooding is a relative elevation above ground elevation.
  • Property - Property, or a property parcel, consists of land and the buildings on it, along with its natural resources such as crops, minerals or water


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