Dune Stabilization

How does dune stabilization work?

Dunes can be stabilized using indegenous grasses and other plants which help by “reducing the velocity of waves and absorbing their energy” (Measures for Stabilizing Coastal Dunes, USDA). These plants take root and begin to form a strong, thick barrier which anchors the sand dune and helps keep sand in place.

Alternative dune stabilization techniques include cross walks and sand fences. Often, dune stabilization requires a combination of methods including planting and structural work. 

Planting takes an extensive amount of work to complete. First, indegenous plant seeds must be obtained, then site preparation, planting, fertilization, and mulching are required. Following the planting process, irrigation needs to be done in order to maintain required moisture levels. 

Structures like sand fences form barriers to wind velocity. These sand fences can be highly effective when installed correctly, however, they are expensive.

Installing dune stabilization vegetation and structures is not the end of the process. The dune must be continuously maintained. 

“A dune system, like a chain, is no stronger than its weakest point. Consequently, to receive maximum protection from wind and water, a strong and uniform dune line must be main- tained. Blow-outs, wash pits, and other natural or human-produced damage must be repaired quickly to prevent weakening of the entire protective dune system.” (Measures for Stabilizing Coastal Dunes, USDA)

What are threats to sand dunes?

Sand dunes are threatened by both naturally-occurring and human-caused erosion. Sand is vulnerable to wind and water erosion because it is easily displaced. Newly formed dunes are most vulnerable to erosion since vegetation has not had time to form deep root systems. Once vegetation mats can form, dunes are more protected. 

In the past, property owners often removed vegetation from the dune, which led to severe erosion. The erosion of dunes is problematic for the environment, but also for homeowners. Rising water levels due to climate change are threatening coastal structures. Dunes act as a first line of defense, however, when they are compromised by vegetation removal, construction, or other human interference, they are no longer able to slow encroaching water.

How does erosion affect sand dunes?

While erosion can cause detrimental effects on sand dune, it’s also the reason sand dunes exist. Sand dunes are formed when marine erosion causes sand to be deposited on the shore. The sand builds up and forms a dune. The dunes grow stronger due to vegetation, and serve as an excellent defense mechanism against coastline erosion. However, when this vegetation is removed, the dunes are easily destroyed by high tides.

“For thousands of years, human activities have been impacting the coastal environment of the Mediterranean Basin through agriculture, husbandry and the deliberate use of fire. In recent decades, tourism has caused important damages on coastal landscapes with the urbanization of the coast, the increase of summer visitors, and the introduction of invasive or exotic species” (http://marinespecies.org/introduced/wiki/Dynamics,_threats_and_management_of_dunes)

Erosion affects dunes differently based on the characteristics of the dune including its height, width, and age (vegetation establishment) as well as the intensity of erosive causes.

How do you rebuild sand dunes? 

Thankfully, sand dunes can be repaired and restored after damage has occurred. Dune restoration needs to be done cautiously and in accordance with local laws. Permits are required in most states before any modifications can be made. 

Dune stabilization techniques can help rebuild dunes. 

How can TrapBags® be used for dune stabilization?

Dunes protect other areas from erosion and flooding but during storm surge events the foot of dunes get eroded. By installing TrapBags® in the core of a dune you ensure that a system is in place for protection even if the rest of the dune is compromised during a storm event.  

All over the world sand dunes are under heavy attack from higher sea levels and more severe weather conditions as a result of the continuous process of global warming. By installing a TrapBag® barrier system inside the dune core, the erosion of the dune can be slowed down drastically or even brought to a halt.

Resources:

https://link.springer.com/referenceworkentry/10.1007%2F0-387-30843-1_160https://www.michigan.gov/documents/deq/deq-wb-nps-dss_250615_7.pdfhttps://coastalcare.org/educate/sand-dunes/

https://books.google.com/books/about/The_Dune_Book.html?id=4OCVPQAACAAJ

https://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/gapmcar3032.pdf

http://marinespecies.org/introduced/wiki/Dynamics,_threats_and_management_of_dunes

https://floridadep.gov/sites/default/files/Building%20Back%20The%20Sand%20Dunes_02.06.17_0.pdf