Coastal processes
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Coastal systems can be divided into erosional shorelines and depositional shorelines based on dominant long-term processes. Erosional shorelines are dominated by erosive forces and typically have high-relief rocky coasts, while depositional shorelines are dominated by depositional processes and include environments like deltas, barrier islands, and reef coasts. Coasts experience various erosive and depositional processes from waves, such as refraction, longshore drift, and swash/backwash, which shape the shoreline over time. Stabilizing eroding coasts involves hard structures, beach nourishment, or relocation, but these approaches have limitations and tradeoffs.
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Coastal processes
- 3. Features of erosional coasts 11.4-Thurman and Trujillo, 2004
- 4. Features of erosional coasts Cabo Rojo, PR Sea arch Wave-cut cliff
- 5. Features of depositional coasts 11.7-Thurman and Trujillo, 2004
- 6. Features of depositional coasts 21, 25-RPI Barrier islands along the South Carolina coast
- 7. A wave moving onto the shore 20.5-Tarbuck & Lutgens, 2005
- 8. Wave erosion
- 10. Wave erosion 20.6, 20.7-Tarbuck & Lutgens, 2005
- 13. Wave Reflection and Refraction
- 15. 10.20b-Garrison, 2005 Wave refraction, Maili Point, Oahu
- 18. Movement of sand by longshore current 20.10-Tarbuck & Lutgens, 2005
- 19. Sediment movement along a beach 11.19-Segar, 2007
- 20. Beach Drift and Longshore Currents
- 22. Swash -> ← Backwash Domes beach, Rincón, PR
- 23. T11.2-Thurman and Trujillo, 2004
- 24. 11.2a-Thurman and Trujillo, 2004
- 25. 11.2a-Thurman and Trujillo, 2004
- 26. Seasonal variation in beach profile 11.19-Segar, 2007
- 27. Barrier Systems Sandy Point, Cape Romain, South Carolina 38-RPI
- 30. 11.9c-Thurman and Trujillo, 2004 Heavily developed barrier islands Tom’s River, New Jersey Barrier islands north of Charleston, SC 21-RPI
- 31. Chesapeake Bay – a drowned river valley Pamlico Sound – a bar-built estuary 12.5-Garrison, 2005
- 33. Coastal erosion is a natural process North Island, SC 32-RPI
- 34. Figure 20.16 Wave erosion caused by strong storms, Long Island, New York Coastal development makes erosion a problem
- 35. Sea-level rise makes the problem worse Studies show a 150x erosion multiplier for sea level rise on sandy shorelines. Hence, for a mean 0.24 m rise by 2050, beaches will recede 36 m (118 ft). ( Leatherman et al., 2000)
- 39. Jetties are built to prevent deposition Figure 20.17
- 42. Figure 20.18 Groins along the New Jersey Shore at Cape May Longshore transport
- 45. Groins and Breakwaters 11.7-Jones and Jones, 2003
- 46. Figure 20.19
- 50. Seawalls are designed to protect beachfront property from erosion 13.21-Segar, 2007
- 51. Figure 20.20 Seawall in Seabright, New Jersey Where’s the beach?
- 55. Responses to Coastal Erosion and Beach Loss
- 56. USGS Illegal extraction of beach sand is one of the major causes of coastal erosion in Puerto Rico
- 57. Morelock et al. Illegal extraction of beach sand is one of the major causes of coastal erosion in Puerto Rico
- 60. Figure 20.21 Beach nourishment, Miami Beach
- 61. USGS Locations of three submerged sand deposit areas on the insular shelf of Puerto Rico Aerial photograph of the Escollo de Arenas, a subtidal sand and gravel deposit that extends some 6 kilometers north-northwestward of Punta Arenas on the northwest coast of Vieques Island, east of Puerto Rico.
Editor's Notes
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- FIGURE 13.15 ( p. 354) Water moves up a beach face at an angle with the wave direction but returns directly down the beach slope. Sand picked up by the incoming wave is washed up the beach and is returned seaward a small distance further down the beach in the direction of the waves. Successive waves move sand progressively along the beach—a process known as “longshore drift” or “littoral drift.”
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- FIGURE 13.18 ( p. 357) Seasonal variation in beach profile. (a) During summer, when waves are relatively gentle, the beach profile is steep, and one or more summer berms form immediately above the high-tide line. (b) Winter or storm waves, especially when combined with storm surges, reach farther up the beach and erode sand from the berm, moving the sand seaward to form one or more offshore bars. The result is a narrower flat-beach foreshore that is cut back to dunes or a winter berm left from periodic extreme winter storms. (c) When storm waves cease, the gentler waves return sand from the offshore bar to the beach, rebuilding its summer profile. If storms are strong in a particular winter, the beach may recede inland, and dunes may be somewhat lowered.
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- FIGURE 13.21 ( p. 361) Seawalls are designed to protect beachfront property from erosion. (a) The Galveston seawall was constructed after the destructive hurricane of 1900. Since the wall was completed in 1962, the beach has eroded along much of its length, leaving the shoreline more exposed to attack by the highest waves of future hurricanes. (b) The barrier island has continued to retreat since the Galveston seawall was constructed. The beach just beyond the end of the wall has now retreated substantially farther shoreward than the wall’s location as a result of the natural process of barrier island retreat and the consequent reduction in the amount of sand in the littoral drift system that occurred once the beach had been eroded away in front of the wall. (c) Seawalls are undermined from the sides and eventually destroyed as sea level rises. CREDIT: (a-b) © D. Segar and E. Stamman Segar.