GEOG201 FINAL (CH13 and CH17)

What is littoral?

(Littoral means pertaining to the coast or shore). Or neashore current play an important role in shaping the topography of the beach.

What is the wave period?

*It is the time required for the wave crest at point A to reach point B.* It is the interval between two successive wave crests passing a fixed point. In the area where waves are generated, it is difficult to identity these wave features clearly since there is a maze of interfering waves of different heights, etc.

What are the coastal processes?

*Waves:* these are the driving forces in the shoreline processes. Waves expend the energy they obtain in the ocean against the margins of the land and the shallow nearshore seafloor. Waves are generated by strong winds blowing across large portions of the open ocean. w

What are the soft solutions/structures to reducing impact of SLR?

- Beach nourishment - Encourage beach dune development - Setbacks for development

The is that climate change is causing sea levels to rise. What are the factors causing climate change?

- Burning of fossil fuels like petroleum and coal - Adds carbon dioxide to atmosphere - Some of this carbon is retained in the atmosphere (increased greenhouse effect) - Temperatures will probably be raised (1.5º to 4.5º C in next century)

With climate change, what will warm waters do?

- Partially melt snowfields, icefields, ice sheets and glaciers releasing water into the oceans increasing ocean's volume - Dilution of ocean's salt water will cause sea to expand - Warmer sea water will cause ocean levels to expand (warmer water needs more room to be accommodated than colder water). This is known as the steric effect

What are the hard solutions to reducing impact of SLR?

- Sea walls - Groynes (also spelt groins) - Rockslides

What are the primary sources of sand?

1. River sediment delivered to the coast through deltas and estuaries 2. Erosion of headlands and sea cliffs 3. The reworking of offshore shelf sediment originating from a variety of sources

What is there to note about the beam berm in relation to the backshore portion?

A beam berm is a nearly horizontal surface on the backshore portion of the beach.

What is shoaling?

As ocean swells approach a land mass, the waves begin to interact with the ocean bottom in a phenomenon called **shoaling**. The waves then change shape when the ration of wave height to wave length equals 0.5.

How are stacks formed?

As the roof of an arch is continually undercut it eventually collapses leaving an isolated STACK.

What are the implications of sea level rise?

As the waters rise: • High tides will become higher • Waves that reach the coast are larger • Wave energy reaching coast is greater • Ability of the waves to destroy (erode) the land is greater • Flooding along the coast will be more widespread WAVES ARE LARGER WITH DEEPER WATER AND GREATER EROSION OF THE COAST RESULTS

What is swash?

As water continues up the beach under its own momentum this is called SWASH.

What is backwash?

As water moves back down the beach face FROM THE SWASH, this is called backwash.

what is the return flow that pours down the beach in a seaward direction?

Backswash

What are the difference between bars and spits?

Bars reach from one headland to the other completely enclosing an area while spits extend out into the open sea. NOTE: •The enclosed area (or a lagoon) sometimes becomes a tidal rash or swamp as it becomes shallower through deposition of overwashed material or sediment deposits from streams

Why do ice shelves respond more quickly to warming than ice sheets or galciers?

Because they are exposed to both warming air above and warming ocean below.

How are arches formed?

Cave is widened and deepened by erosion to form an ARCH.

What are changes on the beach a result of?

Changes on the beach are the result of periodic and predictable fluctuations in the water level (tidal changes) AND aperiodically, that is during elevations of water level (sea level rise) and during coastal storms. For example, a beach berm is formed during deposition of sediment during the backwash mainly during storms or extreme high tides

How are longshore currents generated?

Currents are generated by waves that strike the beach obliguely (at an angle). The currents then move parallel to the shoreline and tend to move sediment parallel to the shoreline for considerable distances.

True/False: The melting of sea ice directly raise sea levels?

False: The melting of the sea ice will NOT directly raise sea levels but will indirectly do so! How this works: • Sea water is darker than ice and therefore has a lower albedo • More shortwave radiation will be absorbed • Therefore more longwave radiation will be emitted causing the atmosphere to be warmer • This in turn may cause further acceleration of the melting of sea ice

True/False: Calving or disintegrating ice shelves raise ocean level?

False: While calving or disintegrating ice shelves don't raise ocean level, the resulting glacier acceleration does, and this poses a potential threat to coastal communities.

What is coastal topography?

High relief shorelines (shown by the presence of sea cliffs and rocks that are highly resistant to erosion) are usually present owing to volcanism and uplift •Coves and inlets are formed by erosional activity

Where does the surf zone end?

It ends where the wave form is lost.

Why are many spits curved?

It is because the expansion of the spit continues in the direction of the current and this explains why spits are curved. Sediments material that makes up the spit is deposited by longshore (littoral) drift.

What is wave length?

It is the distance between the two crests.

What do lower energy waves between storms typically do to the beam?

It typically erodes the berm along its seaward margin and contributes to the overall steepening of the beach face.

What would a berm require to keep growing upwards?

It would require higher water levels.

Why is the exact location of breakers important?

It's important because: 1. determines where the greatest amount of energy is expended and 2. which part of the beach will be subjected to the greatest change

How is the berms elevation determined?

Its elevation is determined by how high the swash runs up the beach

Where does the berm terminate?

Landward, the berm terminates at the base of the sea cliff or foredune and oceanward, it joins the beach face

Since water moving along a beach is responsible for considerable entrainment of sediment of material along the beach face (down and up) how are material sorted?

Lighter material are taken or entrained further up the beach face.

How do rip currents form?

Rip currents are formed when waves break near the shoreline, piling up water between the breaking waves and the beach. One of the ways that this water returns to sea is to form a rip current, a narrow jet of water moving swiftly offshore, roughly perpendicular to the shoreline.

What is a rip current?

Rip currents are powerful, channeled currents of water flowing away from shore. They typically extend from the shoreline, through the surf zone, and past the line of breaking waves. Rip currents can occur at any beach with breaking waves, including the Great Lakes.

How are tombolos formed?

Sometimes a spit may link an offshore island forming what is know as a tombolo.

Where doe waves collide with the landmass?

Surf zone

Where does most of wave erosion occur?

Surf zone

With high velocities and substantial impacts that occur under breaks, these occur in an area called what?

Surf zone

What causes the landward movement of sand and gravel on the beach?

Swash

What is wave refraction?

Swells entering shallow water will change direction as a result of interference with the shape of the ocean bottom. The waves adjust to the contours of the ocean bottome (topography) and so gradually bend according to the shape (configuration) of the shoreline.

What happens to waves with increasing wind velocity?

The **height** and wave **length** becomes larger with increasing wind velocity.

What is the coast?

The COAST is where the land, sea and air (lithosphere, hydrosphere and atmosphere) meet and interact. The coast is therefore affected by variations in tectonic and climate activity. Changes in the sea levels will cause the shoreline to adjust its shape and sediment dynamics.

Define beach face?

The beach face is the sloping section of the beach profile immediately seaward of the berm.

How is the berm formed?

The berm is formed by deposition of sediment during backwash primarily during storm or extreme astronomical tidal conditions.

What is the coastal zone?

The coast is a zone of varying width including the shore and the nearshore zone, out at least to the line where waves break and extending inland to the limit of penetration of marine influences. The crest of a cliff, the head of a tidal estuary or the rising ground behind coastal lowlands, or dunes lagoons or swamps.

How are stumps formed?

The result of a stack being continually eroded eventually forming a STUMP.

How do spilling breaker waves behave?

The top of the wave crest becomes unstable first and flows down the wave front as an irregular foam. In this way, very little of the wave's energy actually impacts the ocean floor in the surf zone.

What is a shore?

The zone between the water's edge at low tide and the upper limit of effective wave action, usually extending to the cliff base. This includes the **foreshore** exposed at low tide and submerged at high tide, and the **backshore**, extending from the normal high tide limited, but inundated during exceptional high tides or by large waves during storms.

How do you tell if there is a rip current?

There are several visual clues to spotting rip currents: A break in the incoming wave pattern, a channel of churning, choppy water, a channel with a different water color, or foam or objects moving steadily away from shore.

What are ocean swells?

They appear as long, low waves. Ocean swells travel great distances (thousands of miles) across the open ocean without losing much of their original energy. When waves reach the coastal zone, the influence of the **ocean bed topography** and **shoreline irregularities** change the wave shape and mechanics.

What characteristics do waves depend on?

They depend upon: **Wind velocity** **Wind duration** and **Fetch** (the distance over which the wind blows) Note: When all three factors are operating at a maximum, waves become quite large.

When do tides and current occur?

They occur twice-daily rise and fall of sea level.

What is wrack line?

This is a line of debris left on the beach by high tide.

What is a beach? Also here be able to identify the breaker zone, surf zone, swash zone, backshore, and berm areas. IMAGE PROVIDED

This is an accumulation of loose sediment such as sand, shingle (rounded pebbles) gravel or boulders, sometimes confined to the backshore but often extending across the foreshore as well. Some beaches extend down to and below low tide level.

What is the breaker zone?

This is the area where the waves are disrupted and is bordered at the seaward side by the **offshore zone**.

What is the nearshore zone?

This is the areas which comprises the **surf zone** (where the waves break on the land) and the **swash zone** (which is covered as each wave runs up the foreshore).

What is a shoreline?

This is where the water meets the land and this migrates up and down according to the tides.

What controls the slope of the berm?

This slope is controlled by many factors and represents a balance between on-shore and off-shore sediment transport• BUT... Storm waves create the most changes on beach profiles

True/False: The beach profile is always in a state of flux constantly adjusting.

True

What is the Steric effect?

Warmer sea water needs more room to be accommodated than colder water. It expands more. This ultimately causes ocean levels to rise.

What causes headlands?

Waves converge on the land and energy is concentrated on the headland areas. As they bend (refract) towards the coves and bays, their energy is diffused. Wave erosion therefore takes place at the high energy wave points and deposition takes place at the low energy wave points.

What are surging breakers?

Waves where the wave crest remains essentially unbroken but the base of the wave front advances up the beach in a sudden lunge. NOTE: The type of breaker wave may depend upon the bottom topography.

How are caves formed?

Weak areas are attacked by waves and opened to form a cave ( due to erosion and hydraulic action).

What is an ice sheet?

• An ice sheet is a mass of glacial land ice extending more than 50,000 square kilometers (20,000 square miles). • The two ice sheets on Earth today cover most of Greenland and Antarctica. • During the last ice age, ice sheets also covered much of North America and Scandinavia • Together, the Antarctic and Greenland ice sheets contain more than 99 percent of the freshwater ice on Earth. • The Antarctic Ice Sheet extends almost 14 million square kilometers (5.4 million square miles), roughly the area of the contiguous United States and Mexico combined.

What are ice shelves?

• An ice shelf is a thick slab of ice, attached to a coastline and extending out over the ocean as a seaward extension of the grounded ice sheet. • Ice shelves range in thickness from about 50 to 600 meters, and some shelves persist for thousands of years.

What is longshore drift?

• As waves approach the shoreline at an angle, a current is set up that runs parallel to the shore • This current moves material along the bottom of the sea • The current is called a longshore current • The process of the movement of material is called longshore drift

What are the economic implications of sea level rise?

• Cities that depend upon beaches for tourism will lose their economic base (main money earner) - City of Miami Beach - through beach erosion • Coastal regions with an agricultural economy will suffer from flooding (Bangladesh) • Ground water for drinking will be mixed from salt from sea water intrusion (Jakarta)

What are the local factors that increase problems (exacerbates) of sea level rise?

• Land is sinking in some areas - Oil extraction - Groundwater extraction - Starvation of land deposits of silt, e.g. the Nile Delta - Sand mining

How does sea level rise affect people?

• Large populations are located within 50 miles of the coast • As the waters rise: • High tides will become higher • Waves that reach the coast are larger • Wave energy reaching coast is greater • Ability of the waves to destroy (erode) the land is greater • Flooding along the coast will be more widespread • Many persons live in areas that are close to sea level or even below sea level • Not all coastal areas are threatened by sea level rise. For example, places located on cliffs

What is attrition and corrosion?

• Small chunks of rocks are reduced in size as turbulent water movement cause them to hit against each other and against cliff faces • Corrosion/abrasion: Rock particles are hurled against the cliff face and headlands and this acts like sandpaper, causing the rocks to be worn away

What are Barrier islands?

• These are elongated landforms that have been formed by deposition of beach material offshore or across mouths of inlets • They extend above the normal level of high tides • (bars are submerged for part of the tidal cycle) •These islands consist of sand or gravel delivered by longshore drifting or carried in from the sea floor and deposited by wave action as beaches •Behind the beaches there may be beach dunes (placed by wind action) •They develop best where the tide range is small •They develop in a variety of ways and no single explanation will be suitable for all of them

What is hydraulic action?

• This is effective on rock and cliff faces that have cracks and fractures • Advancing waves compress air in the rock cavities producing a pneumatic affect in the cracks • As the wave recedes, the external pressure is instantaneously released, and the compressed air within the rocks exerts an outward stress that helps to weaken the cracks

Where do depositional shorelines occur?

•These features occur where the supply of sand is abundant and local ocean forces are capable of transporting sediment •(for sediment to be transported, it first has to be entrained before it is finally deposited)

Why do we care about corrosion with rocks?

•This affects rocks that are most susceptible to solution. •Seawater does not dissolve limestone and CaCO3 •Rainwater, however, does change the topography of limestone coastal regions

How are coves, inlets, and headlands formed?

•Waves are the agents that shape the coastline •Waves attack weak materials (softer rocks) leaving more resistant outcrops •Constant erosion causes these weaker sections of shoreline to retreat rapidly •Weaker areas indent to form coves or inlets and more resistant areas remain to form headlands