1. Coastal Erosion and Management

2. What is Coastal/Shoreline erosion?
The gradual or rapid removal of sediment from the coastline

3. What is Shoreline Erosion?
Shoreline erosion happens when an agent of erosion, mostly water, breaks down and carries away sediment from the beach, or bluffs above.
Coastlines are constantly changing due to the action of waves, currents, and tides.
Landslides and cliff retreats are part of the natural process of coastal erosion along the shore.

4. Management of Erosion
The desire to build structures on coastlines has often interfered with the natural erosion processes.
Protecting human-built structures from coastline erosion has been going on for centuries.

5. Structures Lost to Coastal Erosion

6. Structures Lost to Coastal Erosion

7. abcnews.go.com

8. Management of Erosion
Humans have invented many ways to prevent erosion, and protect structures.
Examples include hard-armor and soft-armor engineering.
(Photo: David Melville and Ying Chen)

9. Hard-armor Engineering
Requires the use of rock, concrete, or metal
Examples include: seawalls, groynes, riprap, jetties, breakwaters
Groynes
© Bruce Molnia, Terra Photographics
Jetty
Breakwater
© EPA
Seawall

10. Soft-armor Engineering
The placement of plant materials into structures that are designed to withstand wave action.
Appropriate where there are suitable conditions for plants to grow.
As the plants grow, their root structures naturally stabilize the shoreline

11. Vocabulary Coastline/Shoreline Bluff Toe erosion Marine erosion
Longshore drift
Seawall
Groynes
Riprap
Jetty
Breakwater

12. Coastline/Shoreline
The line along which a large body of water meets the land

13. Bluff A steep bank or cliff, especially one formed by water erosion

14. Toe Erosion Erosion at the base of a landform
As waves hit against the base of the bluff, material begins to wear away, leaving the above material unsupported.
geosurvey.ohiodnr.gov

15. Marine Erosion Erosion due to:
Hydraulic Action - waves breaking against the foot of a cliff
Abrasion - rocks scraping against the land
Corrasion- a rock thrown against the cliff face from a surging wave
Attrition-rocks carried by seawater colliding

16. Longshore Drift
Waves that hit the beach at an angle carry sand and gravel up the beach face at an angle. When the water washes back, the sediment is carried straight back down the beach face. Individual particles are moved along the beach in a zig-zag pattern.

17. A wall or barrier built to prevent the sea from encroaching on or eroding an area of land
Seawall

18. Groyne
A low wall built out from the coast to the sea to prevent marine erosion

19. Riprap Naturally interlocking stones that form a barrier

20. Jetty
A structure extended into a sea, lake, or river to influence the current or tide, or to protect a harbor

21. Breakwater A barrier that breaks the force of waves

22. Sources American Geosciences Institute
Michigan Inland Lake Shorelines