Coastal areas are subject to erosion from waves and wind. Hard stabilization slows erosion but disturbs the aesthetic beauty of the shore and alters the natural ecosystem. Learn here about alternatives, including beach nourishment and relocation.
Coastal Erosion and Stabilization
Beaches are picturesque areas of the world where many people go to rest and relax.
Yet, the shoreline itself is never at rest. It is constantly changing in response to powerful forces acting upon it, such as the wind, waves and currents.These forces erode shoreline structures and carry sand down the coast unless barriers are in place to slow or prevent the process. Hard stabilization is the use of man-made protective structures to control erosion. Hard stabilization structures, such as groins, are built at right angles to the shore to prevent the movement of sand down the coast and maintain the beach, while other hard stabilization structures, such as breakwaters and seawalls, are built parallel to the beach to protect the coast from the force of waves. These structures are built to stay in place for years, but they are not always the desired solution because they take away from the aesthetic beauty of the beach. They also interfere with the natural ecosystem, threatening habitats and nesting grounds of native shoreline species.
In this lesson, you will learn about alternatives to hard stabilization, including beach nourishment and relocation.
The alternative to hard stabilization is sometimes referred to as soft stabilization. Whereas hard stabilization relies on the use of constructed barriers, soft stabilization is the addition of vegetation or sand to stabilize the shoreline. You can recall this term by thinking of plants and sand as ‘soft’ alternatives to the solid barrier walls we see used in hard stabilization.
Soft stabilization may involve planting vegetation near the shoreline. This anchors the sand and sediment, which slows erosion caused by wind and waves. Because these methods use only organic materials, the aesthetics and natural habitats of the beach are maintained.
A type of soft stabilization is beach nourishment. Beach nourishment is defined as the process of replenishing sand and sediment lost during erosion. In a way, it is as if the beach is getting ‘nourished’ by the arrival of new sand. With beach nourishment, large quantities of sand are brought in from other locations.
This process can restore the quality of the beach for visitors, and because it widens the beach, it provides added protection from storm waves, making it less likely that they will reach beachfront homes or businesses.However, there are disadvantages associated with beach nourishment. One of the biggest disadvantages of beach nourishment is the high cost involved. Sand is bulky and heavy to transport, so beach nourishment is not always an economically viable option. Also, because sand and other organic materials continue to be subjected to the same forces that caused the erosion in the first place, beach nourishment is not a permanent solution.
The ‘new’ beach must be maintained through constant replenishment.Another disadvantage is that the introduction of non-native sand can adversely affect local marine life. For example, Waikiki Beach in Hawaii utilized beach nourishment to stabilize its shoreline. The coarse, native sand was replaced with non-native sand that was much softer and muddier. As the breaking waves crashed down on the new beach, the softer sand disbursed in the water, turning it cloudy, which resulted in the demise of offshore coral reefs.
Another alternative to hard stabilization is relocation. As you may have guessed, ‘relocation’ means moving structures away from the eroding beach.
If stabilization techniques become too costly or difficult, homes or structures may be relocated.This is what happened with the historic Cape Hatteras lighthouse in North Carolina. The lighthouse was built on a barrier island, which is a sandbar that runs parallel to the coast but remains separated by water. This made for an ideal location to warn ships of the dangerous waters in the area. However, waves continually battered the barrier island, threatening the historic structure.
The installation of hard stabilization structures and beach nourishment were no match for the pounding ocean waves, and in 1999, the entire lighthouse was relocated inland for its protection.
Let’s review. Hard stabilization is the use of man-made protective structures to control erosion. Examples of hard stabilization structures include groins, breakwaters and seawalls.
These structures are not always the desired solution because they take away from the aesthetic beauty of the beach and interfere with the natural ecosystem.An alternative is soft stabilization, which is the addition of vegetation or sand to stabilize the shoreline. A type of soft stabilization is beach nourishment, which is the process of replenishing sand and sediment lost during erosion. Beach nourishment can restore the quality of the beach for visitors, and because it widens the beach, it provides added protection from storm waves. However, there are disadvantages of beach nourishment, including the high cost of transporting sand, the fact that it is not a permanent solution and the fact that non-native sand can adversely affect local marine life.
Another alternative to hard stabilization is relocation, or moving structures away from the eroding beach. The historic Cape Hatteras lighthouse in North Carolina is an example of a structure that was relocated inland for its protection.
Upon completing this lesson, you might be able to:
- Contrast hard and soft stabilization processes
- Describe soft stabilization methods
- Pinpoint the advantages and disadvantages of beach nourishment
- Provide an example of a relocation solution