Combating Shoreline Erosion: Strategies & Techniques - Research Paper

Introduction

Primarily a result of wave attacks, shore erosion destroys property bordering large water bodies. Other regional or local scale erosive forces affect the geomorphology and geology of their site of action (Arthur, 2017). Thus, there exist multiple techniques, technologies, and planning strategies that aim to address the problem of shoreline erosion. The majority of the methods are concentrated towards the protection of property from the destructive effects of wave attacks, while others are specific to the local and regional scale erosive forces affecting the geology and geomorphology of coastlines (Williams et al., 2018). This short essay discusses the techniques, technologies, and crucial design elements and criteria that are applicable in addressing erosion on sheltered coastlines. In this paper, the focus is to discuss four categories that are commonly employed in tackling erosion; management of land use, vegetation cover, hardening of surface, and trapping or adding sand.

Management of Land Use

Decisions on the usage of land can occur at both local and state levels. The measures on land use constitute both temporal and spatial components. Spatial scales vary with the local, regional, state, and federal levels. Traditionally, controls on the usage of land have been employed at the level of an individual, away from the system-level processes that determine erosion (Arthur, 2017). The temporal wing derives from the necessity that the effectiveness of the measures on the use of land depends on their longevity and consistency.

Management measures of land use vary from active to passive approaches. Generally, the management of land use follows the steps of planning, regulation, provision of incentives, and acquisition (Wen et al., 2019). The planning phase includes education of all stakeholders on the significance of prevention of erosion, green planning, seeking technical assistance, community visioning, and restoration and reclamation. The regulation phase of management includes the construction of standards, down-zoning, and institutional reorganization and coordination. The management authorities will then offer incentives such as transfer of development rights, conservation easements, and rolling easements (Park et al., 2016). The acquisition step involves a lot of retirement and fee simple.

The land use management techniques and control measures transfer the shoreline management responsibility from the individual property owner to the community. In this case, these responsibilities are often more challenging to implement compared to a single-action by the property owner (Mendoza et al., 2017). The benefits acquired from these control measures include reduced water quality degradation, increased property values, decreased coastal infrastructure and development, reduced property losses due to erosion, improved ecological status of the coastal lands through the avoidance of fragmentation, and preservation of recreational access.

Application of Vegetation Cover

Vegetation can be crucial in the control of shore erosion by growing appropriate grasses into the existing supratidal and tidal substrate. Planting grasses, however, is effective in sites with limited fetch - roughly below 0.8 km, about 0.5 mi (Arthur, 2017). At locations, the locations with a larger, elements such as sand fill and sill should be added to marsh fringes. These elements will provide a better planting terrace or substrate.

This technique of prevention of erosion can be extended beyond the shore zone and used elsewhere, in areas such as bluffs and upland banks. Different types of bioengineering techniques can be used to control surface runoff and groundwater seepage (Park et al., 2016). Vegetation can be handy in stabilizing banks or bluffs, since plant roots bind soils, forming living and adaptive barriers. A combination of vegetation and graded banks effectively protects against erosion.

Sea Grasses

Seagrasses and other types of submerged vegetation may considerable attenuate waves at low tide. The effectiveness of seagrass beds in the protection of shores against erosion is dependent on seasons. During the winter period, the seagrass in temperate locations become less dense or even completely diminish, providing less protection (Burger et al., 2017). The highest wave protection occurs when the grasses occupy the full length of the water column. The water levels tend to increase with increased storm activity which is associated with winter seasons. Thus, the shoreline is vulnerable to erosion because of the less protection provided by seagrasses.

Artificial replanting of submerged aquatic vegetation is undertaken in subtidal areas after the plants have been lost. Light is necessary for the long-term thriving of seagrasses (Arthur, 2017). Other factors such as wave exposure, sediment composition, and current velocity are important considerations during the replanting of seagrasses.

Vegetated Dunes

The creation of dunes can be a significant method of creation and maintenance of beaches. This method adds sand that nourishes a coastal area, with or without structural controls. Dunes are created along the backshore region, by planting appropriate dune grass species. Dunes grass planting together with sand fencing provide baffling and settlement of sand blown by winds (Park et al., 2016). Also, dune berms can be introduced to provide the basis of dune creation, thus providing the foundation for the process of building dunes.

Hardening the Shore

This is probably the most widely used shoreline technique for the prevention of erosion. Hardening of the shore or bluff is done by building sea walls, revetments, or bulkheads. This method creates a barrier that protects the shore against wave attacks. The design of a traditional hardening design involves the use of stones, concrete, and wood (Arthur, 2017). These materials harden the eroding coastlines.

With increased coastal developments, the level of shoreline hardening increases due to several environmental effects. For instance, a properly constructed and designed structure naturally protects the uplands from strong waves and stops erosion of the shores (Chew & Timpson, 2016). These structures will also block sediments from uplands and nearshore from coming into the sea, by the process known as impoundment. Also, grading and bioengineering techniques are used to stabilize eroding banks and bluff faces, further impounding sediments.

These techniques that impound sedimentation, however, present some adverse outcomes on the quality of the shoreline. If the coastal region has a beach, it starts to reduce in volume and dimension (Fukuda et al., 2019). Hard structures such as revetments and bulkheads increase scour and wave reflection on eroding surfaces, causing a reduction in the width of the nearshore environment and an increased depth of water. Continuation of these processes undermine the effectiveness of bulkheads and revetments and promote erosion on the flanking shores. Thus, a pattern of increased erosion and more hardening is created and their adverse effects continue to grow (Wen et al., 2019). The cumulative impacts of hardening sheltered coasts include loss beaches and intertidal zones and over steepened surfaces.

Trap or Add Sand

Particularly for landowners, creating and maintaining a beach is the most desirable option. One effective method of achieving this goal is adding or trapping sand or gravel on the shores, creating an effective shore planform and cross-section that promotes further protection measures (Williams et al., 2018). Groins and breakwaters are some of the successful techniques used to trap sand on the shores. Groins reduce the volume of sand that is carried downstream. The use of groins and breakwaters are often applied in conjunction with other procedures that add sand on the shorelines.

Groins

They are barrier-type structures that interrupt longshore sand transport, thereby trapping the sand from being carried downstream. These structures are often constructed using concrete, steel, timbers or rock, and are perpendicular to the shore (Park et al., 2016). They extend into the littoral zone from the back shores. By impounding sand, the groin cuts the supply of sediments to the downdrift beach, if present. This process potentially triggers or encourages the rate of erosion on the groin's downdrift side (Arthur, 2017). The beach habitat may disappear due to the increased rate of erosion. As a compensation plan, more sand may be added to the groin project.

Breakwaters

They may be designed as either attached or detached to the shoreline. An attached breakwater connects to the mostly sandy beach shoreline. It is composed of a series of breakwater units and pocket beaches that are designed to maintain the neighboring beach in a designed shore planform (Burger et al., 2017). Detached breakwaters are constructed offshore and sit away from the beach. The shoreline grows between the shade of the structures (Arthur, 2017). Beach fill requirements may occur in case of insufficient sand in the littoral system.

Conclusion

Just like other forms of soil erosion, shoreline degradation presents multiple adverse effects on the environment. Shore erosion destroys coastal property, while other erosive forces affect the geomorphology and geology of their site of action. Thus, there exist multiple techniques, technologies, and planning strategies that aim to address the problem of shoreline erosion. The methods include the management of land use, hardening of coastal surfaces, application of vegetation cover, and trapping or adding sand.

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Wen, S., Zhang, F., Wang, Z., Li, F., Jin, X., & Zhao, J....