energy in coastal systems

Question 1

wind role (5)

Answer 1

primary source of energy

-wind speed high and uninterrupted = high wave energy
-prevailing wind determines direction waves approach and direction sediment transport
-fetch (distance blows) influences energy of waves
-influences wave formation
-can pick up sediment from coast and use it to erode other features

Question 2

waves formation

Answer 2

primary agent in shaping the coastline

wave approaches coast and it becomes shallower
friction with seabed slows base of wave
crest continues move forward and rise
elliptical orbit
wave steepens and breaks and moves up beach as swash

Question 3

constructive waves

Answer 3

low wave height
long wavelength
low frequency (6/min)
spill
weak backwash
move material up beach - gentle slope beach
forming berms (ridges)

Question 4

destructive waves

Answer 4

high wave height
short wavelength
high frequency (10/min)
plunge
strong backwash
erodes material - steep beach

may project shingle up beach forming ridge called storm beach

Question 5

negative feedback of waves

Answer 5

constructive builds beach making steeper
more destructive waves
reduces beach angle
etc

Question 6

what is wave refraction

Answer 6

waves drag in shallower water near headland forming destructive waves which erode headland
part in deeper water moves faster so bends
wave concentrated on headland causing erosion
deposition on beach

waves pile on headland forming longshore current

Question 7

what is a current

Answer 7

permanent or seasonal movement of surface water in oceans

Question 8

longshore current is

Answer 8

flow of water parallel to shoreline
due to waves approaching at angle

Question 9

rip current is

Answer 9

strong currents moving away from shoreline
as sea water piles up along coastline
flow out through breaker zone where change direction coast
dangerous

Question 10

upwelling is

Answer 10

cold deep ocean water replacing warmer surface water
creates nutrient rich cold ocean currents

Question 11

what is a tide

Answer 11

periodic rise and fall in sea level

Question 12

*** how do tides form

Answer 12

moon pulls water towards it creating a high tide and therefore a compensatory bulge of the oceans surface water on the other side of earth

in between experiences low tide

Question 13

***spring tide

Answer 13

moon sun earth all in line
produces high highs and low lows
large tidal range

Question 14

***neap tide

Answer 14

moon and sun perpendicular to earth
low highs and low lows (10-30% lower)
small tidal range

Question 15

what is tidal range

Answer 15

vertical difference between high tide and low tide

larger the range the greater the limit of erosion and deposition
amount of time littoral zone exposed each day increases subaerial weathering

med low range
britain high range so forms wide wave cut platforms

Question 16

types of tidal range

Answer 16

macro= 4m+
meso = 2-4m
micro= 2m -

Question 17

what is storm surge

Answer 17

meterological conditions produce higher water levels than at high tide

north sea has depressions which cause low pressure conditions increasing sea level
1mb drop = 1cm rise
strong winds pile water up against coast causing local sea rise
north sea has funnelling

Question 18

features low energy coast

Answer 18

more deposition
spits and beaches

Question 19

features high energy coast

Answer 19

more erosion
headland/cliffs/wc platforms