Deck 10: Coasts, Beaches, and Estuaries

Question 1

The beach face can have a low region that remains flooded at low tide.This is called a ________.

Answer 1

runnel

Question 2

If sea level is to remain constant, the water budget of an estuary requires that all inputs of water equal To

Answer 2

True

Question 3

Accumulated lag deposits protect a beach from continuing erosion.

Answer 3

True

Question 4

Primary coasts are coasts that have features created by marine processes.

Question 5

A low tide terrace is most likely exposed on a neap tide.

Question 6

A drowned river valley is also known as a ________ coast.

Question 7

An abrupt change in the beach slope caused by the cutting action of waves at normal high tide is known as a beach ________.

Question 8

Tidal currents in an estuary are primarily responsible for mixing.

Question 9

Rip currents move water toward the beach.

Question 10

A coast made regular and linear by wave erosion is a secondary coast.

Question 11

Waves that approach the shore at an angle produce a long shore current that flows parallel to the beach.

Question 12

A semi-enclosed sea at 30 °N is most likely re-supplied with seawater at depth.

Question 13

At present, sea level is decreasing around the world's coasts.

Question 14

Transport of dissolved materials out of an estuary can be estimated from the net T₀transport and its concentration of dissolves materials.

Question 15

Climate change can result in a worldwide ________ change in sea level.

Question 16

The coastal zone includes both water areas and land areas.

Question 17

A partially-mixed estuary generally has a two-layered flow that moves inward at depth and seaward at the surface.

Question 18

Beaches gain sand under severe, high-energy winter waves and lose sand under the milder, low-energy summer waves.

Question 19

The net seaward flow of water in a partially mixed estuary is nearly uniform over depth.

Question 20

The beach is the portion of the coastal zone that extends from the low water line to the coastline.

Question 21

A sand spit formed between an offshore island or rock and the mainland is called a(n)

A) offshore spit.
B) inshore spit.
C) barrier spit.
D) sandbar.
E) tombolo.

Question 22

A coral reef coast is a product of

A) volcanism.
B) erosion.
C) a change in current direction.
D) living organisms.
E) wave action.

Question 23

A coastal circulation cell includes

A) longshore transport.
B) rip currents.
C) onshore transport.
D) All of these are correct.
E) None of these are correct.

Question 24

During the last glacial period sea level was approximately 100 feet lower than today.

Question 25

In an estuary, T_ois always larger than T_i

Question 26

Beaches tend to be wider in winter and narrower in summer.

Question 27

A winter berm tends to be farther inland than a summer berm.

Question 28

Chesapeake Bay is a

A) shallow, well-mixed estuary.
B) deep, well-mixed estuary.
C) shallow, fjord-type estuary.
D) deep, partially-mixed estuary.
E) salt wedge estuary.

Question 29

High-energy waves of winter storms

A) move sand from bars onto the beach.
B) move sand from the beach out to bars.
C) build sand spits and tombolos.
D) hold sand on the beach and keep the beach stable.
E) All of these are correct.

Question 30

Sand dunes are found along coasts in which the sand is transported

A) from the beach toward the sea.
B) from the beach toward inland areas.
C) from inland areas toward the sea.
D) from the beach toward inland areas and from inland areas toward the sea.
E) from the beach toward the sea, from the beach toward inland areas, and from inland areas toward the sea.

Question 31

A beach that is fed by mixed sizes of rocks and particles but shows only large rocks on its surface is

A) an erosional beach.
B) subjected to high waves and strong currents.
C) an armored beach.
D) All of these are correct.
E) None of these are correct.

Question 32

An example of a ria coast is

A) the mouth of the Mississippi River.
B) San Francisco Bay.
C) Delaware Bay.
D) the Gulf of Mexico.
E) southeast Alaska.

Question 33

Pollutants that adhere to suspended particles in an estuary are usually flushed from the estuary by the net circulation.

Question 34

The higher berm found on a beach is formed

A) when large waves occur at low tide.
B) during winter storm conditions.
C) from the slumping of cliffs in the backshore.
D) during periods of low-energy waves in the summer.
E) when neap tides occur during the spring and summer.

Question 35

A coast with fjords is classified as a(n)

A) primary coast.
B) secondary coast.
C) sinking coast.
D) rising coast.
E) equilibrium coast.

Question 36

An estuary with a short flushing time will usually have less carrying capacity for pollutants than an estuary with a long flushing time.

Question 37

A sea stack is formed from the deposition of sediment.

Question 38

Barrier Islands are common features along the coasts of the southeast U.S.

Question 39

A low tide terrace forms

A) seaward of the offshore bar.
B) below the beach face.
C) between high and low water.
D) along the trough.
E) next to the lower beach scarp.

Question 40

A beach in dynamic equilibrium

A) loses sand to the offshore area.
B) gains sand.
C) gains and loses sand in equal quantities.
D) builds sand spits and tombolos.
E) gains sand in the low tide terrace.

Question 41

In a fjord with a shallow entrance sill, the outgoing flow (T_o) is approximately equal to

A) inflow (T_i).
B) freshwater inflow (R).
C) tidal flow.
D) estuary volume.
E) All of these are correct.

Question 42

The beach face

A) is the same as the low tide terrace.
B) lies under the surf zone.
C) is found between high tide and low tide levels.
D) appears between an offshore bar and a low tide terrace.
E) is found between the summer and the winter berm.

Question 43

If S_i is the average salt content of the incoming seawater, and S_o is the average salt content of the exiting surface water in an estuary, the fresh water in the exiting mixed water is

A) S_o/(S_i- S_o).
B) S_i/(S_i- S_o).
C) (S_i - S_o)/S_i
D) (S_i - S_o)/S_i
E) (S_o - S_i)(S_i - S_o).

Question 44

In a deep fjord with a shallow entrance sill, the deep basin water is probably

A) low in oxygen and high in nutrients.
B) low in salinity and high in oxygen.
C) high in oxygen and low in nutrients.
D) high in salinity and high in oxygen.
E) high in salinity and low in nutrients.

Question 45

If tidal currents are slight in an estuary but river flow is very large, which type of estuary is most likely to occur?

A) a partially-mixed estuary
B) a salt wedge estuary
C) a fjord
D) a well-mixed estuary
E) None of these are correct; it is impossible to tell from the information given.

Question 46

An estuary that occurs within the mouth of a river where freshwater flows out to sea at the surface while seawater flows upstream along the bottom is

A) a fjord.
B) partially mixed.
C) well mixed.
D) a salt wedge.
E) All of these are correct.

Question 47

In a shallow, well-mixed estuary such as Delaware Bay, the inward transport of salt is controlled by

A) density.
B) diffusion.
C) advection.
D) waves.
E) tides.

Question 48

Which combination holds true in a partially-mixed estuary?

A) Evaporation - precipitation + runoff = transport in
B) Evaporation - precipitation + runoff = transport in - transport out
C) Transport in - evaporation + precipitation + river runoff = transport out
D) Evaporation - precipitation + runoff = transport in and Evaporation - precipitation + runoff = transport in - transport out
E) Evaporation - precipitation + runoff = transport in - transport out and Transport in - evaporation + precipitation + river runoff = transport out

Question 49

Calculations of flushing times assume that none of the out flowing water is recycled into the estuary. If this assumption is not correct, the actual flushing time is __________ the calculated flushing time.

A) less than
B) greater than
C) the same as
D) not related to
E) None of these are correct.

Question 50

In order for an embayment to qualify as an estuary, it must have both _____ and _____.

A) high evaporation; circulation
B) dilution; no physical isolation from the oceans
C) high evaporation; some degree of isolation
D) dilution; some degree of isolation
E) equal evaporation and dilution; no isolation

Question 51

The influx of seawater at depth in an estuary

A) supplies water to make up for net surface water outflow.
B) supplies salt to compensate for dilution by river water.
C) supplies water to maintain the estuary's water level.
D) All of these are correct.
E) None of these are correct.

Question 52

If the salinity of ocean water at the entrance to an estuary is 30‰ and the average salinity of the estuary is 20‰ what fraction of the volume of water in the estuary is fresh water?

A) 1/2
B) 1/3
C) 1/4
D) 16
E) 1/8

Question 53

In a temperate latitude, estuary

A) evaporation exceeds precipitation.
B) precipitation exceeds evaporation.
C) precipitation equals evaporation.
D) winds and tides control the estuary circulation.
E) tides only control the estuary circulation.

Question 54

If the seawater available to an estuary has a salinity of 30‰ and the seaward-flowing mixed water has a salinity of 20‰ at the estuary entrance, the net volume transport seaward is ________ units per day, if the river input is 10 units per day.

A) 5
B) 10
C) 20
D) 30
E) 50

Question 55

The salt wedge in a river estuary is steeper and more sharply defined during

A) ebb tides.
B) flood tides.
C) low water.
D) high water.
E) slack water.

Question 56

A scarp is

A) an underwater sandbar.
B) an abrupt change in beach slope.
C) a beach fault line.
D) the high water mark on a beach.
E) another name for a berm.

Question 57

Which of the following coastal engineering structures is built parallel to the shoreline?

A) Jetty
B) Breakwater
C) Groin
D) Seawall
E) None of these are correct.

Question 58

If T_o equals the net flow rate of mixed surface water out of an estuary, the estuary volume divided by T_o yields the

A) salt flow.
B) water flow.
C) flushing time.
D) salt residence time.
E) freshwater flow.

Question 59

In a well-mixed shallow estuary, the net seaward flow occurs at

A) the surface only.
B) depth only.
C) middle depths.
D) all depths.
E) slack water only.

Question 60

An estuary with strong tidal mixing and low river input is

A) a fjord.
B) partially mixed.
C) well mixed.
D) a salt wedge.
E) All of these are correct.

Question 61

Inverse estuaries are generally found between

A) 30°N and 30°S.
B) 10°N and 10°S..
C) 50°N and 50°S.
E) 5°N and 5°S.

Question 62

Which part of the beach includes the area between the high and low tide shorelines?

A) Foreshore
B) Backshore
C) Offshore
D) Coastline
E) Berm

Question 63

The circulation of water in an inverse estuary is characterized by

A) bottom water flowing in at the surface and sea water flowing out to the sea.
B) water flowing into the inverse estuary at all depths.
C) bottom water flowing out to the sea and sea water flowing in at the surface.
D) water flowing out of the inverse estuary at all depths.
E) None of these are correct.