Learn what natural infrastructure is and how it is included in flood projections
About natural infrastructure
Natural infrastructure refers to naturally occurring environmental features such as wetlands and open space preserves. These features are not man-made projects constructed explicitly to reduce flooding. However, natural infrastructure like wetlands and open space preserves can reduce flood risk, especially if policy is implemented to preserve these environmentally beneficial features.
Coastal saltmarsh as natural infrastructure
Wetlands are transitional lands between terrestrial and aquatic systems. Shallow surface water and saturated soils favor “water loving” plants in these natural communities. Wetlands are found along coasts and in low lying areas like river floodplains and local depressions. They are also disproportionately valuable natural systems for the level of ecosystem services provided, biodiversity supported, and for their flood reduction potential.
Because wetlands tend to exist in low lying areas and thrive in wet conditions, they are often the first areas to become inundated during flood events. Restricting development in wetlands can keep homes out of harm’s way from floodwaters while also allowing these critically important natural communities to thrive.
The preservation of healthy wetland communities is also a critical component to storm surge attenuation. The dense vegetation and plant communities of wetlands, coastal salt marshes, and mangroves create areas of high friction that can slow advancing storm surge and protect landward development. Wetlands are so valuable to property protection that one square kilometer of wetlands provides an estimated $1.8 million in storm damage prevention (source: Claims Journal, March 2020).
Coastal surge without protection of wetlands.
Coastal surge with protection of wetlands.
Open space preservation is a strategy that reduces flood risk by restricting development in flood-prone greenspaces. These greenspaces 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 a first line of defense for adjacent development, soaking up and storing floodwaters that may have otherwise reached and flooded these properties.
South Cape May Meadows near the southern NJ shore community of Cape May (photo courtesy of Jim Wright/TNC/Lighthawk)
South Cape May Meadows near Cape May, NJ is one example of an open space preservation that was included in First Street’s modeling process. The Cape May peninsula of New Jersey is a known flood prone area due to its coastal location, flat terrain, and history of storm surge damage. Following a particularly costly storm in 1991, a group of stakeholders including the U.S. Army Corps of Engineers, The Nature Conservancy, New Jersey Department of Environmental Protection, and local governments backed the establishment of South Cape May Meadows as open space preserve. The project also included elements of beach, dune, and wetland restoration. Upon its completion in 2007, flood claims following major storm events dropped from an average of $143,713 to $3,713 in the adjacent community of Cape May Point (project information sourced from Naturally Resilient Communities).
South Cape May Meadows near the southern NJ shore community of Cape May.
Flood risk reduction projects
Information on Flood Factor comes from the First Street Foundation Flood Model. Natural infrastructure defines several of the 40 different types of flood risk reduction projects, known as adaptation, that this model considers when calculating and validating flood projections.
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 this flood protection project user input form. The adaptation database contains 23,000 features today. We know there are more projects to include and value your input!