Impacts of sediment management on coastal barrier systems

Coastal sediment management practices, such as dredging and beach nourishment, can have beneficial and detrimental impacts on the physical and ecological resiliency of barrier islands, particularly when sediment is removed from one barrier island system and placed in another, according to the report released by the U.S. Geological Survey.

Developed by the USGS and U.S. Fish and Wildlife Service, the report provides resource managers valuable information they can use to evaluate impacts of sediment removal and placement within barrier islands, including those addressed by the Coastal Barrier Resources System.

The CBRS is comprised of relatively undeveloped coastal barriers along the U.S. Gulf of Mexico, Atlantic Ocean and Great Lakes coasts that are depicted on a set of maps maintained by FWS.

Barrier islands, the narrow low-lying landforms located at the interface of land and sea, play a key role in storm protection for coastal communities and infrastructure and serve as important habitats for many coastal and marine species.

β€œThe study identifies both beneficial and detrimental impacts from sediment management practices depending on where and how they are applied within barrier island systems,” said Jennifer Miselis, USGS research geologist and lead author on the report.

Sediment management actions such as beach nourishment β€” where sand is added to an area to expand beaches and dunes β€” are typically done for coastal hazard mitigation, erosion prevention and flood control.

Some of the key findings in the report illustrate how some barrier island sediment management practices can have negative impacts on seafloor habitats, fish and other marine species, beach habitats and dunes, and the coastal sediment supply that ensures barrier island resiliency.

The report also highlights some positive impacts of sediment management. For example, in addition to the short-term protection from coastal hazards beach nourishment provides, it also increases nesting habitats for some coastal wildlife.

According to Miselis, this report will give decision-makers, resource managers and the public a better understanding of the pros and cons of moving sand within barrier island systems.

It will show that sometimes short-term benefits can have unforeseen impacts that may affect the health of barrier islands and their ecological stability beyond the life of the sediment management project itself.

Photo: USGS