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Climate resilience terminology

Base concepts​

Climate resilience​

Climate resilience is the ability of a community to adapt and respond to the chronic stresses and acute shocks resulting from climate change, while proactively meeting the needs of and improving the quality of life for all citizens. Resilience is the ability of a system to prepare for, withstand, and recover quickly from a disaster. Ideally, resilient systems should recover from an event by becoming stronger than they were prior to the stress.

Coastal resilience​

Coastal resilience is the ability of human and natural coastal systems to prepare for, absorb, recover from, and successfully adapt to hazardous events (like hurricanes and storm surges) and long-term environmental changes (such as sea-level rise and coastal erosion). Coastal resilience infrastructure refers to the systems, structures, and natural habitats designed to protect shorelines and communities from coastal hazards.

1% Annual chance flood​

The 1% annual chance flood (also known as the 100-year flood) has a 1 in 100 probability of being equaled or exceeded in any given year. Areas subject to the 1% annual chance flood are identified on the Federal Emergency Management Agency’s (FEMA) Flood Insurance Rate Maps (FIRMs) and National Flood Hazard Layer available on the FEMA Flood Map Service Center and are referred to as special flood hazard areas. It is important to note that the use of “100-year flood” can be misleading, since floods of this magnitude can occur more frequently than once every 100 hundred years. The 100-year flood is a recurrence interval, which reflects a frequency analysis of past flood events (over 10 or more years) and corresponds to the 1 in 100 probability of occurrence in any given year (the annual exceedance probability).

Base Flood Elevation (BFE)​

Base Flood Elevation (BFE) is the elevation of the 100-year flood or 1% Annual Chance Flood. The BFE is determined by statistical analysis for each local area and is designated on the Flood Insurance Rate Maps (FIRMs). This elevation is the basis of the insurance and floodplain management requirements of the National Flood Insurance Program (NFIP).

Design Flood Elevation (DFE)​

Design Flood Elevation (DFE) is the minimum elevation to which a structure must be elevated or floodproofed, typically defined by local sea level rise and storm surge projections.

Floodproofing​

Floodproofing includes structural or non-structural interventions that reduce flood damage to a space or a building. Dry floodproofing is the practice of sealing a space or a building up to the level of the Design Flood Elevation (DFE) or higher, in order to keep water from entering. Wet floodproofing designs for the movement of water through a space or a building, which equalizes hydrostatic pressure and helps prevent structural failure.

Coastal hazards​

Sea level rise​

Sea-level rise refers to the rise in sea level over time relative to the land at a given location. The warming of Earth is primarily due to the accumulation of heattrapping greenhouse gases, and more than 90 percent of this trapped heat is absorbed by the oceans. As this heat is absorbed, ocean temperatures rise, polar ice melts, and water expands, which contributes to an increase in global sea level. Other factors such as land subsidence may also contribute to relative sea-level rise in some locations

Storm surge​

Storm surge is the abnormal rise in seawater level during a storm, measured as the height of the water above the normal predicted astronomical tide. The surge is caused primarily by a storm’s winds pushing water onshore. The amplitude of the storm surge at any given location depends on the orientation of the coastline with the storm track; the intensity, size, and speed of the storm; and the local submarine topography.

Coastal erosion​

Coastal erosion is the process by which local sea level rise, strong wave action, and coastal flooding wear down or carry away rocks, soils, and/or sands along the coast. All coastlines are affected by storms and other natural events that cause erosion; the combination of storm surge at high tide with effects from strong waves—conditions commonly associated with landfalling tropical storms—creates the most damaging conditions.

Flood protection strategies & infrastructure​

Berm​

A berm is a raised, elongated mound of soil constructed to act as a barrier against water. A berm can redirect or absorb water, slow down runoff, and reduce wave action. It is primarily designed to prevent floodwaters from inundating vulnerable areas by blocking, diverting, or reducing the flow of water. Some berms can be planted with grasses, shrubs, or other plants. Berms, also known as levees, may be reinforced with an interior floodwall to increase stability and reduce seepage under ground.

Elevated roadway​

A raised roadway is a street, highway, or evacuation route that has been built above the base flood elevation. It functions as a resilient infrastructure measure by keeping critical transport networks operational during storm surges, heavy rain, or coastal flooding while acting as a physical barrier to protect adjacent inland properties.

Seawall​

A seawall is a structure built along a shoreline to separate the land from the water. Seawalls are coastal defense structures that protect coastal and inland areas from wave action, storm surges, and flooding, as well as reduce erosion. Seawalls are engineered to absorb, deflect, or redirect the immense energy of crashing waves. They can be vertical, curved, or sloped and made of different materials, such as concrete, steel, treated lumber, and more. Seawalls can extend up from the ground or be built with public walkways, open space, or buildings on top.

Deployable barrier​

A deployable barrier is a temporary or movable structure designed to be quickly set up to protect people, property, or perimeters. They remain stored during normal operations and are rapidly deployed during emergencies or specific events (like crowds or severe weather).

Nature-based solutions​

Nature-based solutions involve the intentional use of natural and nature-based features, like beaches, dunes, islands, marshes and mangroves, coral and oyster reefs, either alone or in combination with traditional gray infrastructure, like cement walls buried inside of sand dunes, to reduce risks to coastal hazards and deliver multiple environmental and socio-economic benefits. Nature-based solutions are sustainable planning, design, environmental management, and engineering practices that weave natural features or processes into the built environment to promote adaptation and resilience.

Coastal dune​

Coastal dunes serve as natural buffers that protect coastlines from storm surges, waves, and sea-level rise. They act as the first line of defense against flooding while supplying sand to nourish eroded beaches. An artificial or reinforced dune is a shoreline protection measure where a new mound of compatible sediment is built along the back of the beach, seaward of the area to be protected. Dune nourishment provides shoreline protection by adding compatible sediment to an existing dune. With artificial dunes and dune nourishment, sediment is brought in from an offsite source, such as a sand and gravel pit or coastal dredging project.

Marsh​

A marsh is a type of wetland, which is an area where water covers the ground all year or for varying periods of time during the year. Marshes are usually treeless and dominated by grasses and other plants. Many species of animals live in marshes, including birds, reptiles, fish, and mammals. There are three types of marshes: tidal salt marshes, tidal freshwater marshes, and inland freshwater marshes. Salt marshes protect shorelines from erosion by creating a buffer against wave action and by trapping sediment, reducing the flow of flood waters, and absorbing rainwater. As rising seas cause lower marsh elevations to flood, marsh vegetation may migrate toward higher, drier ground.

Green infrastructure​

Projects and practices incorporating the natural environment or engineered systems that provide or supplement natural processes or work in concert with natural systems to provide flood, fire, or drought risk reduction, or clean water or air benefits. Green infrastructure practices protect, restore, augment, or mimic ecological processes. Examples include bioswales, rain gardens, permeable pavement, green roofs, constructed wetlands, and planting trees.

Bioswale​

A bioswale is a landscaped channel designed to collect and manage rainwater runoff from surfaces like streets, parking lots, and rooftops. Instead of sending stormwater directly into drains, a bioswale slows the water down and helps it soak into the ground naturally. Bioswales are an example of “green infrastructure” that help reduce flooding, improve water quality by filtering pollutants, and add greenery to neighborhoods. They are commonly planted with grasses, shrubs, and other hardy vegetation, giving them the appearance of a planted ditch or garden bed.

Managed retreat / Strategic relocation​

Managed retreat (also known as strategic relocation) is an intentional, coordinated effort to permanently move community members, structures, and systems away from locations that are prone to prolonged or frequent high-intensity climatic events, such as flooding, wildfires, and hurricanes, that cause destruction beyond a community’s ability to cope. In the coastal context, this involves adapting to coastline change, generally by either preventing construction in a vulnerable area or removing structures already in the vulnerable area, rather than attempting to prevent it when site-specific conditions indicate that perimeter protection or adaptation is not favorable Retreat scenarios may include assisted relocation to high ground and outside of the flood risk area, required setbacks from the coastline, or voluntary buy-out programs.