Coastal protection

coastal protection

Coastal protection is a broad term that includes measures taken to prevent the loss of land and infrastructure due to coastal erosion. These can be built structures, such as seawalls, breakwaters and groynes, or nature-based solutions, such as marshes and beaches.

Seawalls are massive concrete or metal walls that stretch across coastlines. They are typically used to reduce wave energy and protect against flooding. However, they do not look very pretty, and can be destroyed easily during storms. Other features of coastal protection include groynes, breakwaters and offshore dikes.

Coastal protection can be effective on its own, or it can be a part of a larger system that also includes nature-based and community-based solutions. The latter approach focuses on the health of the natural environment and includes a focus on protecting coastal habitats. In addition, it is important to assess how the combined effectiveness of individual protective elements affects the overall function of the protection.

Protection provided by living systems, such as marshes and beaches, can change with changes in vegetation growth and seasonal water levels. While the protection provided by these systems can be less than that offered by hard structures, it is still a valuable option. It can slow down or even stop the entrainment of sand, which is an essential component of restoring a beach.

Coastal protection also includes pre-event actions, such as warning systems, that can minimize the human impact of destructive waves and floods. These can be implemented before, during or after the event.

Hard structures, such as seawalls and breakwaters, provide a first line of defense. Designed to limit the erosive power of waves, these systems can withstand large waves and crashing waves.

A second type of protection comes from coastal structures that provide protection after a disaster. Structures that survive an extreme event can be reused to help communities recover from smaller, less destructive events. For example, a repurposed groyne can serve as a terminal groyne, preventing longshore drift from bringing materials to nearby places.

Whether a community relies on the effectiveness of its existing structures or invests in a new engineered solution, it is important to evaluate the benefits of the structure relative to the overall benefits of the community. This evaluation requires quantitative monitoring of the shoreline, which can improve the ability to measure protective capacity.

Using pre-event and post-event actions, communities can reduce the damage from a range of hazards, including flooding and erosion. This can be accomplished by evaluating the assets at risk, the space available to adjust to changes in the coastal environment, and the benefits of maintenance.

Shoreline protection can be evaluated in many ways, and field surveys can be useful in assessing the effectiveness of current protection. As a result of recent disasters, a more holistic approach to characterizing coastal events is underway. This includes quantitative monitoring of the living shoreline. Field surveys of the aftermath of Hurricane Katrina and other disasters have produced a number of useful results.