# Chapter 11 Study Guide, Version 2: Coastal Hazards

This version follows the textbook section by section. Review each section's summary, key ideas, examples, and questions before moving to the next section.

## Chapter Learning Objectives

- **LO:1:** Discuss the role of plate tectonics influencing coastal zone morphology and process.
- **LO:2:** Explain coastal processes, such as waves, beach forms and processes, and rising sea level.
- **LO:3:** Summarize the effects of sea-level rise on coastal processes.
- **LO:4:** Explain why coastal erosion rates vary along different U.S. coastlines.
- **LO:5:** Synthesize the coastal erosion hazard.
- **LO:6:** Summarize the potential link between coastal processes and other natural hazards.
- **LO:7:** Evaluate how human use of the coastal zone affects coastal processes.
- **LO:8:** Summarize what we can do to minimize coastal hazards.
- **LO:9:** List options available for coastal management.

## 11.1 Introduction to Coastal Hazards (LO:1)

### Section summary

The coast, where the sea meets the land, is one of the most dynamic environments on Earth. Continental and oceanic processes converge there, producing landscapes that can change rapidly. Coastal topography is strongly influenced by plate tectonics, and human development increasingly conflicts with natural coastal processes.

### Passive and active coasts

- **Tectonically passive coasts** are far from plate boundaries. The east coasts of the United States and Canada and the Canadian Arctic coast are examples. They typically have wide continental shelves, barrier islands, and sandy beaches. Rocky shorelines are mostly limited to New England, Atlantic Canada, and Arctic islands where ancient mountains meet the sea.
- **Tectonically active coasts** are near plate boundaries. The west coasts of the United States and Canada are near the San Andreas transform fault and the Cascadia subduction zone; Hawaii, Puerto Rico, the Virgin Islands, and southern Alaska are also active. Mountain building produces sea cliffs and rocky shorelines, and long sandy beaches are less abundant.
- Climate and organisms also shape coasts: seasonal ice and glaciers (Alaska, Canada, Great Lakes), marsh vegetation (temperate regions), and mangroves (subtropical regions).

### Growing coastal exposure

The United States has about 150,000 km (93,000 mi.) of shoreline, including the Great Lakes. Approximately 40 percent of the U.S. population lives in coastal counties, which account for only about 10 percent of the land area; coastal population density is about six times that of inland counties, and it grows further during vacation periods.

### The most serious coastal hazards

1. Strong coastal currents, including rip currents in the surf zone and tidal currents in narrow bays and channels.
2. Coastal erosion of beaches, dunes, and sea cliffs.
3. Storm surge from tropical and extratropical cyclones.
4. Tsunamis, especially along the Pacific Ocean.

### Case study: Folly Island

Folly Island, South Carolina, is a barrier island about 11 km south of Charleston. It grew from sand dune ridges 4,000 to 5,000 years ago and is home to about 3,000 people. Its ocean shoreline has been retreating for at least 160 years, in the early twentieth century at about 2 m per year. Jetties built at Charleston Harbor in 1896 blocked the natural southward drift of sand, causing severe erosion on Folly and Morris Islands.

### Key terms

- **Coast:** The dynamic zone where the sea meets the land.
- **Barrier island:** A long, narrow sandy island separated from the mainland by a lagoon or bay.
- **Sea cliff / bluff:** A steep shoreline cliff (seashore) or lakeshore slope eroded by waves.
- **Tectonically passive / active coast:** A coast far from / near a plate boundary.

### Section 11.1 review questions

1. How does plate tectonics influence coastlines?
2. What are the most serious coastal hazards?

## 11.2 Coastal Processes (LO:2)

### Section summary

Waves generated by offshore winds expend their energy at the shoreline and are the main agents that shape beaches. Wave size, refraction, and breaker type control where energy is concentrated, and littoral transport moves sand along the shore.

### Waves

Wave size depends on:

1. **Wind velocity** — stronger winds make larger waves.
2. **Wind duration** — longer-lasting winds impart more energy.
3. **Fetch** — the distance the wind blows across the water; a longer fetch allows larger waves.

Sets of similar waves travel long distances and arrive in a repeating "surf beat." **Rogue waves**, much larger than surrounding waves, form mainly by **constructive interference** when multiple waves meet, and also depend on undersea irregularities and currents. Rogue waves can sink ships and endanger beachgoers.

Three parameters describe a wave:

- **Wave height (H):** difference between trough and crest.
- **Wavelength (L):** distance between successive crests.
- **Wave period (T):** time for successive waves to pass a reference point.

In deep water, water particles move in circular orbits that shrink with depth to about half a wavelength. As waves reach shallow water, **period stays constant, velocity decreases, height increases**, and the waves eventually break. Wave energy is approximately proportional to the **square of wave height**, so a 2 m wave has four times the energy of a 1 m wave, and a 5 m storm wave about 25 times.

### Wave refraction and breakers

**Wave refraction** is the bending of wave fronts as they slow in shallow water. Wave energy **converges** on rocky **headlands** (higher waves, more erosion) and **diverges** along adjacent shorelines (lower energy), so erosion tends to straighten the shoreline.

- **Plunging breakers** form on steep beaches and are more erosive.
- **Spilling breakers** form on wide, nearly flat beaches and tend to deposit sand.

### Beach form

A **beach** is a landform of loose material (sand or gravel) accumulated by wave action. Beach sand composition reflects its source (shell and coral, volcanic rock, or quartz and feldspar). Landward, a beach ends at a sea cliff or bluff, dunes, or permanent vegetation. Onshore features include the gently sloping **berm** and the steeper **beach face**; the part washed by the uprush and backwash is the **swash zone**. Offshore are the **surf zone** (turbulent water moving shoreward after breaking) and the **breaker zone** (where waves peak and break), with **longshore bars** and **longshore troughs** beneath the breakers.

### Sand transport

Sand moves parallel to shore by **littoral transport**, which includes:

- **Beach drift:** zigzag movement of sediment in the swash zone.
- **Longshore drift:** transport by **longshore currents** flowing parallel to shore in the surf zone.

Both occur when waves strike the coast at an angle. **Updrift** is the direction from which sediment comes; **downdrift** is the direction it moves. Longshore drift on U.S. seacoasts is most often southward and commonly moves about 150,000 to 300,000 m³ per year; Great Lakes rates are about 6,000 to 69,000 m³ per year.

### Key terms

- **Fetch:** Distance the wind blows across the water.
- **Rogue wave:** An unusually large wave, commonly formed by constructive interference.
- **Wave height / wavelength / wave period:** Basic wave measurements.
- **Refraction:** Bending of wave fronts in shallow water.
- **Plunging / spilling breaker:** Erosive breaker on a steep beach / depositional breaker on a gentle beach.
- **Berm / beach face / swash zone:** Onshore beach features.
- **Surf zone / breaker zone / longshore bar / longshore trough:** Offshore beach features.
- **Littoral transport:** Movement of sediment along the shore by beach drift and longshore drift.

### Section 11.2 review questions

1. What three factors determine the size of waves?
2. What are rogue waves?
3. Define wave height, wavelength, wave period, and wave energy.
4. What is wave refraction?
5. Define plunging and spilling breakers.
6. What defines a beach?
7. What is littoral transport?
8. Differentiate between beach drift and longshore drift.

## 11.3 Sea-Level Change (LO:3)

### Section summary

Sea level at a shore is always changing. **Relative sea level** is what we observe at a particular coast; it reflects both the movement of the land and the movement of the water. **Eustatic sea level** is global sea level, controlled by the volume of water in the oceans and the shape of ocean basins.

### Eustatic and relative sea level

- **Eustatic sea level** changes when the amount of ocean water or the shape of ocean basins changes. Today, climate (average air temperature) is the main control. Rising temperature causes **thermal expansion** of seawater (about 1.6 mm per year, roughly half of the current eustatic rise) and the melting of glaciers, ice caps, and the Greenland and Antarctic ice sheets (about 1.5 mm per year). Present eustatic rise is about 3 mm (0.12 in.) per year. Over long time spans, plate tectonics changes ocean-basin shape.
- **Relative sea level** superimposes local and regional processes on eustatic change. Land can rise or fall slowly (crustal response to melting ice), or rapidly during earthquakes (Montague Island, Alaska, rose nearly 10 m during the 1964 M 9.2 earthquake). Deposition, erosion, and subsidence also shift the shoreline. Subsiding coasts, such as Louisiana's, are especially vulnerable.

### Short-term changes

- **Astronomical tides** are produced by the gravitational pull of the Moon and, to a lesser extent, the Sun. Tides are predictable and can create hazardous currents and raise storm-surge damage when surge arrives at high tide.
- **Weather** changes relative sea level over hours or days. Wind speed has a greater effect than atmospheric pressure; storm surge is an extreme case of wind-driven swell moving landward. Major hurricanes can add a meter or more from low pressure.
- **El Niño** can change sea level by up to about 30 cm (12 in.) over days to months and increase West Coast storminess.

### Key terms

- **Relative sea level:** Sea level observed at a particular coast, reflecting land and water movement.
- **Eustatic sea level:** Global sea level, controlled by ocean water volume and basin shape.
- **Thermal expansion / contraction:** Volume change of water as its temperature changes.
- **Astronomical tides:** Daily and seasonal sea-level changes caused by the Moon and Sun.
- **Storm surge / El Niño:** Short-term sea-level changes driven by weather and ocean-atmosphere patterns.

### Section 11.3 review questions

1. Define relative and eustatic sea-level rise, and explain the corresponding coastal hazards.
2. How does sea level change temporarily for very short periods of hours or days?

## 11.4 Geographic Regions at Risk from Coastal Hazards (LO:4)

### Section summary

Coastal hazards occur on seacoasts and large lakes alike. Coastal erosion is essentially a worldwide hazard, driven in part by rising sea level, and erosion rates vary widely with rock type, sand supply, wave energy, storms, and human modification.

### Where hazards occur

Large lakes (Great Lakes, Great Bear, Great Slave, Lake Winnipeg) develop coastal conditions, but tsunamis and hurricanes are generally absent. Only Lake Okeechobee (Florida) and Lake Pontchartrain (Louisiana) have experienced significant hurricane storm surges in historic times.

### Erosion rates in the United States and Canada

All 30 U.S. states and Canadian provinces bordering the ocean or the Great Lakes have coastal erosion problems. Typical rates:

| Region | Typical erosion rate |
|---|---|
| Southeastern U.S. barrier islands | average about 0.3-1.0 m/yr; locally up to 8 m/yr |
| Florida and Gulf Coast | 0.3-2 m/yr (highly variable) |
| Great Lakes shorelines | average about 0.3-1 m/yr; locally up to 15 m/yr |
| U.S. West Coast | 0.1-0.3 m/yr |

Strong nearshore currents, especially rip currents, are common where surf is regular and strong (for example, California and Hawaii) and can occur on any coast with breaking waves, including the Great Lakes. They are especially dangerous around groins, jetties, and piers.

### Rising sea level and low coasts

Low, tectonically passive coastlines are most affected by rising sea level. A 0.3 m (1 ft.) rise can shift the shoreline landward 30 to 300 m on gentle, shallow coasts such as those from Long Island south to Florida, parts of Arctic Canada, and Alaska's North Slope. Rapidly subsiding coasts, such as parts of Louisiana, may be inundated even more. Many low Pacific **atolls** (for example, in the Marshall Islands, Micronesia, and Palau) are in danger of inundation.

### Section 11.4 review questions

1. List factors that help determine the rate of coastal erosion at a particular beach.
2. Why are average rates of erosion at the regional scale useful but difficult to interpret?

## 11.5 Effects of Coastal Processes (LO:5)

### Section summary

Coastal processes create safety hazards for individuals (strong currents, storm surge, tsunamis) and long-term hazards for communities (coastal erosion and rising sea level). Rip currents are a major cause of drowning, and the beach budget is a key tool for evaluating erosion.

### Rip currents

**Rip currents** form when a series of large waves piles up water between the longshore bar and the swash zone; the water escapes through narrow gaps in the longshore bar, forming fast currents that flow perpendicular to shore. They can exceed **6 km per hour**, vary from about 15 to 100 m wide, and extend tens to hundreds of meters offshore before widening and dissipating beyond the breakers.

- In the United States, rip currents kill more than **100 people each year** and cause more than **80 percent** of about 60,000 surf rescues annually.
- To escape, **do not panic** and do not try to swim straight back. Swim **parallel to the shore** until out of the current, then swim to shore; if unable, wave and yell for help.

### Beach budget

A **beach budget** accounts for the input, storage, and output of sand on a beach:

- **Inputs** include littoral transport from updrift, erosion of dunes and sea cliffs, and river sediment.
- **Outputs** include littoral drift away, storm-wave return flow carrying sand offshore, and wind blowing sand inland.

If input exceeds output the beach grows; if output exceeds input it erodes. A **littoral cell** is a coastal segment with its own sand sources, transport paths, and sinks (such as a submarine canyon). Dams that trap river sediment (for example, on the Rio Grande) reduce beach sand supply and worsen erosion.

### Sea cliff and bluff erosion

Sea cliffs and lakeshore bluffs erode from the combined action of waves and land processes (running water and landslides). They are most eroded during storms and nor'easters, and the beach at their base protects them between storms. Human activities that increase erosion include uncontrolled surface runoff (often with urbanization), increased groundwater discharge from watering lawns, and added weight from structures such as houses, walls, and pools. **LIDAR** (airborne laser surveying) can measure elevation changes to about 15 cm and track cliff and beach erosion.

### Key terms

- **Rip current:** A fast, narrow return flow of water through the surf zone.
- **Beach budget:** The balance of sand input, storage, and output on a beach.
- **Littoral cell:** A coastal segment with linked sand sources, transport, and sinks.
- **Washover channel / overwash:** A channel cut through a barrier by surge / sand deposited landward by surge.

### Section 11.5 review questions

1. How are rip currents produced, and how can you escape from one?
2. Why is the beach budget such a valuable tool in risk analysis for coastal erosion?
3. Assume there are several beach homes near point X in our beach budget example. What advice would you give them based on the calculations? What would be your response if there were high-rise coastal resorts near point X?

## 11.6 Linkages between Coastal Processes and Other Natural Hazards (LO:6)

### Section summary

Coastal processes are closely linked to many other natural hazards, and the links often intensify one another. Wave erosion, subsidence, storms, and sea-level rise combine to worsen coastal flooding, erosion, and landslides.

### Important linkages

- **Earthquakes, volcanic eruptions, and tsunamis** can radically change the shape of a shoreline.
- **Cyclones** produce storm waves, storm surge, and coastal flooding that drive erosion; storm surge and heavy inland rain combine to cause widespread flooding.
- **Subsidence** makes coasts more vulnerable to both freshwater flooding and storm surge.
- **Landslides** are triggered when wave erosion undercuts sea cliffs and bluffs, especially if structures add weight at the top.
- **El Niño** can increase the intensity and frequency of extratropical cyclones on the U.S. West Coast (as in 1982-83), increasing coastal erosion.
- **Climate change and rising sea level** increase the energy of high-energy storms and the reach of erosion and flooding.

### Section 11.6 review questions

1. How are coastal processes linked to other hazards, such as earthquakes, tsunamis, landslides, volcanic eruptions, hurricanes, and flooding?

## 11.7 Natural Service Functions of Coastal Processes (LO:6)

### Section summary

Although erosion, rip currents, and sea-level rise may seem purely hazardous, coastal processes also provide important benefits. Erosion creates scenic features and supplies the sand that builds beaches, and beaches perform many ecological and cultural services.

### Natural services

- Erosion produces **aesthetic and recreational features** such as cliffs, rocky headlands, and sea arches, and is often the only significant source of beach sand (as on Cape Cod's eastern shore).
- Sandy beaches **transport and store sand**, supply sediment to lagoons, estuaries, and dunes, **dissipate wave energy** as a buffer, break down pollutants and cycle nutrients, provide nesting and roosting habitat for shorebirds and seabirds, filter and discharge groundwater, maintain biodiversity (for example, California grunion), provide food for fish and birds, and offer cultural and recreational value.
- Storm disturbance of coastal zones and coral reefs renews these ecosystems and maintains their diversity.
- Coastal processes provide aesthetic value and recreational opportunities such as swimming, surfing, sailing, fishing, and sunbathing.

### Section 11.7 review questions

1. List some of the natural service functions of beaches.

## 11.8 Human Interaction with Coastal Processes (LO:7)

### Section summary

Human use of the coast is a major force that alters shorelines. Engineering structures that interfere with littoral transport cause erosion and deposition problems, and development on barrier islands and bluffs increases exposure.

### Regional examples

- **Atlantic coast:** Barrier islands from northern Florida to New York have been heavily altered. In Maryland, Ocean City on Fenwick Island was developed with high-rise buildings, and dunes were removed in many places, increasing hurricane vulnerability. The Ocean City inlet was stabilized with jetties in 1935, which blocked southward sand drift; since then, the north end of Assateague Island has lost about 11 m per year, roughly 20 times the natural rate, while beaches north of the inlet widened.
- **Gulf Coast:** In the Texas coastal zone, human modification has accelerated erosion by 30 to 40 percent over the past century, largely due to engineering structures, subsidence from groundwater and petroleum withdrawal, and river damming.
- **Pacific coast:** Armoring with seawalls is widespread from San Diego to Seattle, though the trend has stalled in some areas.
- **Great Lakes:** Erosion is periodic and worst at high lake levels. Lake Michigan levels have fluctuated about 2 m since 1860; high water in 1985 caused an estimated $15-20 million in damages. Lake Michigan bluffs have eroded at about 0.4 m per year on average. Dune-protected bluffs erode more slowly; exposed sites and groundwater seepage erode faster; protective structures are locally beneficial but often accelerate erosion nearby.
- **Canada:** Canada has the world's longest ocean coastline. Atlantic Canada can erode up to 10 m per year; the Arctic Beaufort Sea coast erodes 1-2 m per year. Canada spends about $1 billion per year on coastline projects.

### Key terms

- **Barrier island:** A long, narrow sandy island separated from the mainland.
- **Spit:** A sandy peninsula that extends from the mainland into the water.
- **Littoral cell:** A coastal system with linked sand sources, transport, and sinks.

### Section 11.8 review questions

1. Describe the main causes of erosion at Assateague Island, located just south of Ocean City on Fenwick Island.
2. What factors affect the severity of erosion on Great Lake shorelines? How applicable are these factors to general coastal erosion?

## 11.9 Minimizing the Effects of Coastal Hazards (LO:8)

### Section summary

Coastal hazard reduction generally uses **hard stabilization** (engineering structures) or **soft stabilization** (adding sand and working with natural processes). Hard structures often protect property but damage the beach, whereas soft approaches are usually more environmentally compatible but expensive and temporary.

### Hard stabilization

- **Seawalls** are built parallel to the coast to protect buildings. Their vertical faces reflect storm waves and redirect energy, promoting beach erosion over decades and producing narrower beaches; they can fail by washing away or being overtopped and undermined. Many geologists believe seawalls cause more problems than they solve where beach preservation is a goal.
- **Groins** are structures perpendicular to the shore, usually in **groin fields**, built to trap sand from longshore drift. They widen the beach **updrift** but cause erosion **downdrift**. Nourishing the groin can reduce downdrift erosion.
- **Breakwaters** are offshore structures (attached or detached) that protect harbors. They block littoral transport, causing deposition and erosion that may require artificial sand bypassing.
- **Jetties** are usually built in pairs at a river or inlet mouth to keep a channel open. Like groins, they widen the updrift beach and starve downdrift beaches.

### Soft stabilization

- **Beach nourishment** places sand on a beach to create a positive beach budget. It is aesthetically preferable and provides recreation and protection, but it is expensive and must be repeated. The **Miami Beach** project (from the mid-1970s) cost about $62 million over 10 years, added about 18 million m³ of sand, and produced a 200 m-wide beach, with vegetated dunes added as a buffer.
- **Coastal zone bioengineering (CZB)** uses living or dead plants to help control erosion. Examples include dunes stabilized with native grasses and the use of Sargassum seaweed in Galveston, Texas; palm trees near the high-tide line at Refugio State Beach, California, also retard erosion.

### Management

- **Adaptive management** uses science, statistics, and modeling to reduce uncertainty; promotes sustainable coasts; communicates alternatives; and recognizes that management must change as conditions change.
- **Integrated coastal zone management** aims to maintain the ecological function of the coast, encourage sustainable solutions, and reduce conflicts among coastal users.
- **E-lines and E-zones** map expected erosion. The **E-10 line** is the expected position of the shoreline in 10 years, and the **E-10 zone** is the area between the current shoreline and that line. Rising sea level is treated as an imminent hazard in the E-10 zone; movable structures are allowed in intermediate and long-term zones (E-10 to E-60), and permanent large structures must be landward of the E-60 line. Only a few states (including California, Florida, New Jersey, New York, North Carolina, and South Carolina) use erosion-based setback distances.

### Principles for the coast

1. Coastal erosion is a natural process rather than a natural hazard.
2. Any shoreline construction causes change and adverse secondary effects.
3. Stabilization protects property, not the beach itself, usually benefiting relatively few people at public expense.
4. Engineering structures designed to protect a beach may eventually destroy it.
5. Once built, shoreline structures create a costly trend that is difficult to reverse.

### Key terms

- **Hard stabilization:** Engineering structures (seawalls, groins, breakwaters, jetties).
- **Soft stabilization:** Beach nourishment, land-use planning, and bioengineering.
- **Beach nourishment:** Adding sand to a beach to replace eroded sand.
- **Breakwater / jetty / groin / seawall:** Structures built in or along the shore.
- **Adaptive management / integrated coastal zone management:** Structured, science-based coastal management approaches.
- **E-line / E-zone:** Mapped expected erosion position and associated setback zone.

### Section 11.9 review questions

1. How can a seawall increase beach erosion?
2. Why are beach groins used? What problems can groins cause?
3. Why do breakwaters and jetties cause beach erosion problems?
4. What are the advantages and disadvantages of beach nourishment?
5. What is coastal zone bioengineering, and what are its advantages and possible shortcomings?

## 11.10 Perception of and Adjustment to Coastal Hazards (LO:9)

### Section summary

People generally perceive land as stable, even though coastlines are dynamic and change over months and years. Risk perception depends on experience, proximity to the coast, and the probability of damage. Coastal erosion is often a "wicked problem" with conflicting interests, so management requires compromise and periodic review.

### Perception

A study of sea cliff erosion near Bolinas, California, found that residents in the immediate hazard area were well informed and saw erosion as a serious threat; people a few hundred meters away knew little about its frequency or severity; and people farther inland barely perceived it as a hazard. Many people do not recognize rip currents or plunging waves as hazards.

### Adjustments

Adjustments to coastal erosion fall into three categories:

1. **Beach nourishment** — a "soft solution" that imitates natural processes.
2. **Land-use change** — avoiding hazardous areas or relocating threatened buildings, the "managed retreat solution" (also soft).
3. **Shoreline stabilization** — structures such as groins and seawalls, a "hard solution."

For strong currents, the best adjustments are education, awareness, supervised swimming, and posted warnings. For erosion, management often uses **adaptive management** and **integrated coastal zone management**, along with erosion-rate estimates and E-lines/E-zones.

### Case studies

- **Cape Hatteras Lighthouse (North Carolina):** Built about 500 m from the ocean, it was only about 100 m away by the early 1990s. In 1999 the 4,400-ton lighthouse was moved more than 800 m inland using 120 jacks in a "Unified Jack System"; it should be safe for 50 to 100 years.
- **Pointe du Hoc (France):** A World War II historic site on a 30 m sea cliff that eroded about 10 m in 60 years. Rather than retreat, authorities chose a site-specific hard solution: filling sea caves at the cliff base with several hundred cubic meters of concrete and using rock bolts (about $6 million), aiming to buy about 50 years. The study estimated this would reduce retreat by about half, but the upper weak soil still produces small landslides, so maintenance will be required.

### Section 11.10 review questions

1. What are the main adjustments to managing coastal erosion?
2. What are the attributes of adaptive management?
3. What are the goals of integrated coastal zone management?
4. What are E-lines and E-zones?
5. Why was moving the Cape Hatteras Lighthouse successful?
6. Could erosion control measures for Pointe du Hoc in France be widely applied to other eroding sea cliffs? Why or why not?

## Connections among the Sections

- **11.1 to 11.2:** Plate tectonics and climate set the coastal setting in which waves, beaches, and littoral transport operate.
- **11.2 to 11.3:** Waves and currents move sand, while changing sea level shifts the shoreline and the beach budget.
- **11.3 to 11.4:** Rising eustatic and relative sea level, plus storms and subsidence, determine where coastal hazards are greatest.
- **11.4 to 11.5:** Regional exposure shapes the effects of rip currents, erosion, and the beach budget.
- **11.5 to 11.6:** Erosion, flooding, and landslides are linked to cyclones, earthquakes, tsunamis, subsidence, and climate change.
- **11.5 to 11.7:** The same processes that erode the coast also create beaches, habitats, and recreational value.
- **11.7 to 11.8:** Human use of the coast alters sediment supply and causes erosion and deposition that harm others.
- **11.8 to 11.9:** Understanding human causes helps select hard or soft stabilization and appropriate management.
- **11.9 to 11.10:** Adjustments work best when people perceive the hazard and adopt science-based, adaptive management.

## Chapter-Wide Comparison Questions

- How do tectonically passive and active coasts differ in landforms and coastal processes?
- How do wave height, wavelength, wave period, and wave energy relate?
- How do spilling and plunging breakers differ, and what does each do to a beach?
- How does wave refraction concentrate or disperse energy along a shoreline?
- How do beach drift and longshore drift combine in littoral transport?
- How do eustatic and relative sea level differ, and what processes control each?
- How do rising sea level, subsidence, and tides affect coastal flooding and erosion?
- Why do coastal erosion rates vary along the Atlantic, Gulf, Pacific, and Great Lakes coasts?
- How do rip currents form, and how does the beach budget help evaluate erosion?
- How do sea cliffs and lakeshore bluffs erode, and how can people increase the rate?
- How are coastal processes linked to earthquakes, tsunamis, cyclones, flooding, landslides, and subsidence?
- What natural service functions do beaches and coastal processes provide?
- How do barrier-island development, dune removal, and engineering structures alter coastal processes?
- How do seawalls, groins, breakwaters, and jetties affect erosion and deposition?
- How do beach nourishment and coastal zone bioengineering work, and what are their limits?
- How do adaptive management, integrated coastal zone management, and E-lines/E-zones reduce coastal risk?
- How do perception and proximity to the coast influence adjustment to coastal hazards?
- How do the Folly Island, Ocean City/Assateague, Cape Hatteras, and Pointe du Hoc examples illustrate the interaction of natural processes and human decisions?

## Practice Questions

1. Define coast, barrier island, sea cliff, bluff, spit, and littoral cell.
2. Explain how plate tectonics and climate influence coastal morphology in North America.
3. Describe the three factors that control wave size and define wave height, wavelength, and wave period.
4. Explain rogue waves and how wave energy relates to wave height.
5. Describe wave refraction and its effects on headlands and adjacent beaches.
6. Compare plunging and spilling breakers and identify the beach conditions that favor each.
7. Identify the onshore and offshore features of a beach.
8. Explain littoral transport, beach drift, and longshore drift, including typical rates.
9. Distinguish eustatic from relative sea level and explain thermal expansion and melting ice.
10. Describe how tides, weather, storm surge, and El Niño change sea level over short periods.
11. Identify major regions at risk from coastal hazards and typical erosion rates.
12. Explain how rip currents form and describe how to escape one.
13. Explain the beach budget and how a dam can change it from positive to negative.
14. Describe sea cliff and bluff erosion and the human activities that accelerate it.
15. Trace linkages among coastal processes and earthquakes, tsunamis, cyclones, flooding, landslides, and subsidence.
16. List the natural service functions of beaches and coastal processes.
17. Explain how barrier-island development and coastal engineering can increase erosion (Ocean City/Assateague example).
18. Compare the causes and effects of seawalls, groins, breakwaters, and jetties.
19. Describe beach nourishment and coastal zone bioengineering, with their advantages and disadvantages.
20. Explain adaptive management, integrated coastal zone management, and the use of E-lines and E-zones.
21. Explain how perception of coastal hazards changes with proximity to the coast.
22. Use Folly Island, Cape Hatteras, or Pointe du Hoc to explain how science and human decisions affect coastal losses.

## Quick Review Checklist

Before the quiz or test, make sure you can:

- define coast, barrier island, sea cliff, bluff, spit, littoral cell, eustatic sea level, and relative sea level;
- compare tectonically passive and active coasts;
- identify the most serious coastal hazards;
- list the three controls on wave size and define wave height, wavelength, and wave period;
- explain rogue waves, wave refraction, and wave energy;
- compare spilling and plunging breakers;
- identify beach features: berm, beach face, swash zone, surf zone, breaker zone, longshore bar, and longshore trough;
- explain littoral transport, beach drift, and longshore drift;
- distinguish eustatic from relative sea level and explain thermal expansion and ice melting;
- describe short-term sea-level changes from tides, weather, storm surge, and El Niño;
- identify regional erosion rates and areas most at risk from rising sea level;
- explain how rip currents form and how to escape one;
- compute and interpret a beach budget;
- describe sea cliff and bluff erosion and human contributions to it;
- trace coastal links to earthquakes, tsunamis, cyclones, floods, landslides, and subsidence;
- list the natural service functions of beaches;
- explain how development, dune removal, and structures alter coastal processes;
- compare seawalls, groins, breakwaters, and jetties;
- explain beach nourishment, coastal zone bioengineering, adaptive management, integrated coastal zone management, and E-lines/E-zones;
- describe how perception of coastal hazards varies with distance from the coast; and
- use the Folly Island, Ocean City/Assateague, Cape Hatteras, and Pointe du Hoc examples to explain coastal hazards and adjustments.