Temporal Variations And Their Influence On Coastal Environments

Question 1

What is a tide and what are the types of tide?

Answer 1

Tides are the rise and fall of sea level.

Semidiurnal tides have 2high and 2 low tides every 24 hours

Diurnal tides have one high and one low tide every 24 hours

Question 2

How are tides formed?

Answer 2

Gravitation effect of moon and (lesser the sun) which pulls water on earth towards it to create high tides. Between the 2 high tide areas are low tides.

Question 3

What is a spring tide?

Answer 3

Twice a month the earth moon and sun are aligned so the gravitational pull is greatest. Creates higher than average tides

Question 4

What is a neap tide?

Answer 4

When the sun and moon are at right angles to each other, gravitational pull is weaker. Creates lower than average tides.

Question 5

What is tidal range?

Answer 5

Difference in height between high and low water during the monthly tidal cycle.

Question 6

What are the 3 types of offshore and onshore currents?

Answer 6

Tidal currents
Shore normal currents
Longshore currents

Question 7

What’s a tidal current?

Answer 7

Water floods the intertidal zone at high tide, moving and depositing sediment. Falling tide =ebb tide, where sediment moves in reverse direction

Question 8

Shore normal currents

Answer 8

Waves align parallel to the coastline pushing water straight up the beach. Water returning directly away from the shore can form strong fast moving channels of water called rip currents

Question 9

Longshore currents

Answer 9

Waves approach the shoreline at an oblique angle but return straight down the beach, moving sediment parallel to the shore

Question 10

How are waves created and what affects them?

Answer 10

Created by the transfer of energy from the wind blowing over the sea surface.

Stronger winds increase frictional drag and the size of waves

Question 11

Constructive waves vs destructive waves

Answer 11

Constructive
Less than 1m high, long wave length up to 100m, longer period 6-8/min, gentler/spill over, low energy, swash up beach to form a berm, increase gradient of upper beach.

Destructive
Taller than 1m high, short wavelength 20m, shorter period 10-14/min, steep and plunging, high energy, backwash down beach, steeper upper beach(storm beach) gentler lower beach