Types of Flood Adaptation

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Learn about the different adaptation types considered when calculating and validating flood projections on Flood Factor.


The First Street Foundation Flood Model considers 40 different types of flood risk reduction projects, known as adaptation when calculating and validating flood projections on Flood Factor®. Learn more about each adaptation below.

The Adaptation Team continues to collect information on the flood infrastructure that exists across the country to make sure the Flood Model includes as many adaptation projects as possible. If you know of any projects that are not shown today, please help the team by submitting an issue here; select "Questions or comments about Flood Factor" and then "share home or area protections." The adaptation database contains 23,000 features today. We know there are more projects to include and value your input!


Acquisition refers to the purchase of private property by the government for public use. In the case of flood acquisitions, the process involves the purchase of a property in a floodway in order to reduce the damage of future flooding on the site and/or for properties adjacent to the one being acquired.


Flooded property from the Metropolitan Water Reclamation District of Chicago - Chicago, Illinois

Beach nourishment 

Beach nourishment projects involve the process of adding sediment to a beach to provide a buffer for coastal erosion as part of a coastal defense scheme.


Beach renourishment at Fort Pulaski National Monument, Georgia


Bioswales are channels designed to convey stormwater runoff.


Bioswale in Washington, DC


Breakwaters are barriers built out into a body of water to protect a coast or harbor from the force of waves.


Breakwaters at Colonial National Historic Park, Virginia


Buyout programs are a specific subset of property acquisitions in which private lands are purchased, existing structures demolished, and the land maintained in an undeveloped state for public use in perpetuity. Acquisition of a property in a floodway is intended to reduce the risk of future flooding for the property and/or those adjacent. 


Red River Grand Forks, North Dakota 1997 flood events led to buy-outs across the state 


Flood control channels are large and empty basins that let water flow in and out, except during flooding, or dry channels that run below the street levels of some larger cities. When a flood occurs, the water will run into these channels and eventually drain into a river or other body of water.


Flood channel example

Coral reef 

Coral reefs are naturally occurring structures that protect the shoreline from wave action and subsequent erosion.


Coral reef example


Culverts are structures that allow water to flow through a barrier, like in the case of a road. These structures are used to divert water through specific areas and maintain flow, therefore preventing flooding on the properties adjacent to them.  


A typical box culvert built to reduce flooding - Napa, California


Dams are highly engineered barriers constructed to hold back water. Flood control dams block floodwaters and then either release them under control to the river below, store them, or divert the water. Dams have been used to control floodwaters for centuries. 


Folsom Dam - California 

Detention basin 

Detention basins are an area meant to store water to protect against flooding for a limited period of time.


Boneyard detention basin - Champaign, Illinois   


Ditches are narrow channels used for drainage.


Typical ditch example


Dunes are mounds of sand or sediment that can act as barriers to flooding. They are naturally created by wind and wave action but are often engineered along beaches to form a protective ridge against tidal surge events. 


Beach dune - Virginia Beach, VA


Dikes are walls or embankments that work to prevent flooding from rivers or seas. 


Dike embankment 

Earthen berm 

Earthen berms are ledges made of soil or gravel that can prevent flooding. These structures are formed into a ridge to direct runoff water away from the area of protection. 


Earthen berm construction

Elevated roads

Elevated roads are roads raised to prevent flooding.


Elevated road and sidewalk - Miami, Florida 


Flood walls are walls built along a shoreline or bank to protect from flooding. These engineered structures temporarily constrain the waters of a river or other waterway as it rises due to extreme weather events. 


Napa River flood wall- Napa, California

Floodplain restoration 

Floodplain restoration projects involve the process of restoring a river’s floodplain to its original state. These natural habitats are restored after being impacted by the construction of levees, dikes, and the draining of wetlands and marshes. Restoring floodplains leads to a reduction in flooding, restoration of species habitat, increase in water quality, and recharging of groundwater. 


A restored marsh, pond, and willow habitat - John D. Rockefeller, Jr. Memorial Parkway, Wyoming


Levees are an embankment built to prevent flooding from a river. These engineered structures are located along rivers, streams, creeks, and tributaries as well as lakes and on the coast. Typically these embankments are made of earthen materials such as clay and other soils that are impervious but they also can be made of concrete and stone. Levees work to protect surrounding areas from certain levels of flooding; once this level is exceeded levees can be overtopped.


Construction of the 17th Street Levee - Washington D.C.

Living breakwater

Living breakwaters are offshore structures designed as barriers to limit wave energy. These engineered green infrastructure projects aid in flood risk reduction through erosion prevention, wave energy attenuation, and enhancement of ecosystems and social resilience by restoring natural habitat and increasing friction in the nearshore environment. 


Rendering from SCAPE of the Rebuild by Design Living Breakwater project - Staten Island, NY 

Living shoreline

Living shorelines are a shoreline stabilization technique that uses vegetation to slow down wave action. Native wetland plants, natural structures, and shellfish are installed in an effort to trap sediment and absorb waves. This type of green infrastructure project helps to stabilize eroding shorelines to support adjacent land, ultimately helping to alleviate nearby flooding. 


Delaware Bay Living Shoreline - Delaware 


Mangroves are a species of tree with an extensive root system that slows down wave action. These trees thrive in places along the coastline that other species cannot due to their ability to process salt water. The roots of mangroves are above ground and are able to trap sediments which prevent erosion. The entire structure of the tree - the roots, trunks, and canopy - reduce the force of oncoming waves and storm surge. The presence of mangrove forests along shorelines has proven to protect inland communities during hurricanes and tsunamis. 


Mangrove Forest - Biscayne National Park, Florida 

Marsh or wetland creation

Marsh or wetland creation projects consist of the construction of a marsh or wetland on a site that never existed before. Constructed marshes and wetlands are built in places specifically for water to be stored, whether from agricultural runoff, wastewater, or stormwater. In the case of their role in storing stormwater, they reduce flooding inland at constructed marsh and wetland project sites. 


Planting marsh grass on the shoreline - Fort Eustis, Virginia 

Marsh or wetland restoration 

Marsh or wetland restoration projects consist of the reconstruction of a marsh or wetland. Many wetlands have been drained to create agricultural land or filled to accommodate urban sprawl. Restoration is the process of returning marshes to the landscape to replace those lost in the past. Restoration can be done on a large scale, such as by allowing rivers to flood naturally in the spring, or on a small scale by returning wetlands to urban landscapes. These projects recreate important spaces for water to be stored, therefore reducing flooding inland of it. 


Parker River National Wildlife Refuge Coastal Wetlands - Newburyport, Massachusetts

Open space preserve  

Open space preserves are areas of protected or conserved land. Open space preservation is a strategy that reduces flood risk by restricting development in flood-prone green spaces. These green spaces might exist in naturally low-lying areas and river floodplains, thereby making them more prone to flooding. Restricting development in flood-prone open spaces keeps homes out of harm’s way from floodwaters. Preserving these open spaces can also act as the first line of defense for adjacent development, soaking up floodwaters that may have otherwise reached and flooded these properties.


West River Memorial Park - New Haven, Connecticut

Oyster reef

Oyster reef projects are a type of living shoreline. Building an oyster reef increases sediment buildup behind the reef. This allows the oyster habitat to play a major role in reducing wave momentum by increasing friction at the bed and/or surface. 


Oyster reef building - MacDill Air Force Base, Florida

Pervious pavement 

Pervious pavement projects are porous concrete installations that allow rainwater to pass through them.  These projects are installed anywhere concrete would be, such as a sidewalk or parking lot. Pervious pavement structures avoid a runoff by allowing rainwater to seep through their structure, which reduces local flooding.


Crosswalks made of pervious pavers - Shorewood, Wisconsin  


Pipes are an engineered structure that moves water from one place to the next. They are often built in conjunction with other stormwater structures such as pump stations and stormwater vaults in order to create a stormwater management system that helps to keep rain and riverine flooding off of the properties they are specifically designed to protect. 


Stormwater pipe - Chesapeake Bay, Maryland 

Pump, deployable 

Deployable pumps are mobile structures that relocate large volumes of water. These structures are often brought into areas that experience flooding for a limited duration of time like during a king tide or riverine flood event. 


Deployed pump station - Miami, Florida

Pump station 

Pump stations are permanent structures that help protect areas by moving away large volumes of water during flooding events. They range in size, from some that serve one city block to others that protect entire cities. The largest pump station in the world was built in 2011 as part of the one-billion-dollar West Closure Complex project which protects New Orleans from a major storm surge event. 


Pump station at the West Closure Complex - Belle Chase, Louisiana 

Rain gardens 

Rain gardens are a type of green infrastructure built to mitigate pluvial (stormwater) flooding. These features are constructed vegetated areas designed for enhanced infiltration and collecting rainwater from surrounding impervious areas. These features detain and infiltrate rainwater locally, rather than allowing it to be carried away as runoff, which contributes to flooding.


Rendering of a rain garden from NYC DEP 

Retention pond  

Retention ponds are areas designed with additional storage capacity to hold surface water runoff during rainfall events. In their most basic form, they have a large surface for inflow and a small area for outflow, which allows for an effective strategy to manage excess urban runoff. Retention ponds are also known as wet ponds, wet detention basins, or stormwater management ponds. Many areas have even more colloquial names for these structures like “catch-all” in parts of Tennessee. 


Retention pond “catch-all” in the Wildwood community - Blount County, Tennessee


Seawalls are coastal defense structures that mitigate flooding by protecting against the action of tides and waves. This engineered structure is built where the sea makes an impact directly upon the land along the coast. Seawalls protect areas inland of them from the action of tides, waves, or tsunamis.


Galveston Seawall - Galveston, Texas

Sediment accretion 

Sediment accretion happens when coastal sediment returns to the visible portion of a beach or shoreline. As sediment accumulates it builds up a lost coastline. This regained land aids in armoring the shoreline against future storms. More land at the coastline offers more protection to inland areas from wave run-ups and flooding.


Jetty with sediment accretion - Cape Hatteras National Seashore, North Carolina.

Stormwater/sewer system upgrade 

Stormwater/sewer system upgrades are an update to an existing system that better handles flood water during rain events. Many urbanized areas were not built to handle current development patterns that cause an increase in pervious surfaces, such as concrete. These surfaces increase stormwater runoff putting stress on often aging stormwater systems. Large upgrades are needed in order to be able to prevent flood events for current and future populations in towns and cities.  


Upgraded stormwater drains along I-5 near the Skagit and Whatcom county lines - Washington State


Spillways are structures used to provide controlled release of water from a dam or levee. Normally these structures are used only during flood events. Spillways help to prevent erosion and breakage of dams since they are instrumental in the controlled release of excess water that builds up at the dam.  


Orville Dam Spillway, California 

Stormwater vault 

Stormwater vaults are underground structures designed to manage excess stormwater runoff. These engineered structures help to prevent large quantities of water from entering nearby waterways during rain events. They are particularly useful on properties where there is an insufficient amount of space to store runoff water. Often built in urban settings, stormwater vaults are found underneath parking lots or other open spaces on site in order to accommodate high volumes of water. 


A typical stormwater detention vault - Washington State

Tide gate 

Tide gates are engineered structures that regulate water levels and water quality in rivers, streams, and creeks. They have an opening where the tide can move freely in one direction but then close automatically or manually to prevent water from flowing in the other direction- where flooding would typically occur.  


West River tide gates - New Haven, Connecticut


Valves have an automatic mechanism that prevents water from flowing up from the water source through a stormwater pipe and onto the street once the pipe is at capacity. These structures are often used to combat sea level rise-related tidal flood events on residential streets. They are known by many names: backflow preventer valve, duck valve, and tidal valve. 


Duck Valve - Delray Beach, Florida


Weirs are small dams built on a river to regulate the level of water or flow. These impervious barriers are constructed in a manner that raises the water level on the upstream side, encouraging flow through the waterway. 


Typical weir

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