Coastal Geography, Estuaries

Question 1

Estuary

Answer 1

A semi-enclosed coastal water body that receives inputs of water and sediment from both the open ocean and rivers

Question 2

What are the three main characteristics of estuaries?

Answer 2

Typical funnel shape, two way flows, easily catch sediment

Question 3

What are the four classification types of estuaries?

Answer 3

Water balance, geomorphology, vertical salinity structure, hydrodynamics

Question 4

Is fresh or salt water more dense

Answer 4

Fresh water is less dense than salt water so it flows above it

Question 5

What two factors does mixing depend on?

Answer 5

Volume and speed of flow

Question 6

What are the two types of sediment in estuaries?

Answer 6

Bedload and suspended sediment

Question 7

Bedload

Answer 7

Larger/heavier sediment that is fluvially transported via traction and saltation

Question 8

Suspended sediment

Answer 8

Already dissolved sediment that is fluvially transported via suspension and solution

Question 9

What two factors does water circualtion depend on?

Answer 9

Tidal flow and river flow

Question 10

What are the three types of estuarine circulation?

Answer 10

Salt wedge, partially mixed, fully mixed

Question 11

What are the two requirements for a salt wedge estuary?

Answer 11

Requires a small tidal range (<2m) and a large river flow

Question 12

What are the two requirement for a salt wedge estuary?

Answer 12

Requires a small tidal range (<2m) and a large river flow

Question 13

What is the one main characteristics of a salt wedge estuary?

Answer 13

The differences between saline and fresh water produces a wedge of salt water below the fresh river water

Question 14

What are the two main requirements for a partially mixed estaury?

Answer 14

Requires a large tidal range (>3m) and a small river flow

Question 15

What are the two main characteristics of a partially mixed estuary?

Answer 15

The mixing of tidal currents and river flow produces a vertical salinity gradient.

Saline resides at the bottom while fresh resides above

Question 16

What are the three main requirements for a fully mixed estuary?

Answer 16

Requires a very large tidal range (with strong currents), a very low river flow, and a very wide estuary mouth (>500m)

Question 17

What are the two main characteristics of a fully mixed estuary?

Answer 17

No vertical salinity variation.

Lateral salinity gradient is produced by coriolis forces (earth rotation)

Question 18

Floculation

Answer 18

The bonding of clay and silt particles due to electrostatic attraction

Question 19

What type of sediment is found in a salt wedge estuary, and what is its origin?

Answer 19

Course sediment is deposited at the tip of the salt wedge whilst finer sediment is carried to the estuary mouth. At the salt wedge, floccualtion occurs.

Orign: River sources

Question 20

What type of sediment is found in a partially mixed estuary, and what is its origin?

Answer 20

Course sediment is deposited near the mouthwhilst finer sediment is carried landward. Turbidity maximum occurs at the peak of suspended fine sediment at the limit of salt water

Origin: Most is from marine sources

Question 21

Turbidity maximum

Answer 21

A concentration of suspended sediment that reduces water clarity

Question 22

What two factors does the morphology of an estuary depend on?

Answer 22

Whether it is wave dominated (microtidal) or tide dominated (macrotidal)

Question 23

What are the tidal ranges of wave and tide dominated estuaries?

Answer 23

Wave dominated (microtidal): <2m

Tide dominated (macrotidal): >4m

Question 24

What are the three distinct zones of a wave dominated (microtidal estuary)?

Answer 24

1. A sandy barrier and tidal delta
2. A muddy lagoon
3. A sandy and gravelly river delta

Question 25

What are the thee distnict zones of a tide dominated estuary?

Answer 25

1. A sandy tidla bar complex
2. A sandy tidal flat
3. A sand and gravelly river channel

Question 26

Tidal delta

Answer 26

A fan-shaped deposit of sediment formed on the landward side of an estuary