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Transcript of 04. garis pantai_2014(1)
8/20/2019 04. garis pantai_2014(1)
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SHORELINES
a) Wavesb)Longshore transport
c) Erosional shoresd)Depositional shorese) Emergent and submergent shores
f) Sealevel rise
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= orbital wave (waves ofoscillation)
Energy advances
But:
Water does not!Water moves in circular orbits
Ocean WAVES
a) Wavesa) WavesShorelinesShorelines
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Waves ‘feel bottom when it comes to within half of thewavelength
Wave length decreases wave height increases "t critical #oint the wave becomes too stee# and brea$s
Surf sloshes onshore
Breaking WAVES
%ig& ' &'
a) Wavesa) WavesShorelinesShorelines
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Summertime and wintertime beach conditions
Summertime beach Wintertime beach
a) Wavesa) Waves
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Wave refraction strongly influences erosion and sediment transport
Waves travel moreslowly in shallow waterso they refract towards
the beach.
a) Wavesa) Waves
Waves refract aroundheadlands, increasing
wave impact onheadlands, decreasing it
on beaches. Fig. 17.13
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Longshore transport • Swash is oblique,
bac wash straight,causing beach drift of
sediment along the shore
• !blique waves also causelongshore currents parallel to beach
b) Longshore transportb) Longshore transport
Beaches = *ivers of sand!Beaches = *ivers of sand!
ShorelinesShorelines
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Longshore currents and rip currents
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Wave refraction along an irregular shoreline
• Wave energy isconcentrated atheadlands anddispersed in
bays• Causes erosion
of headlandsand creation oferosionalfeatures Figure 10-1 b
c) Erosional Shoresc) Erosional ShoresShorelinesShorelines
%ig& Story ' &'
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• !eadland• Wave-cut cliff • Wave-cut
terrace"bench#• Sea cave• Sea arch• Sea stac$
c) Erosional Shoresc) Erosional ShoresShorelinesShorelines
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ShorelinesShorelines
BEACHES
+ Source of beach sediments
, rivers, cliff erosion, marine life
+ Sand com#osition
d) Depositional Shoresd) Depositional Shores
Beaches
See %ig& ' &'-
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ShorelinesShorelines
BEACHES
+ Source of beach sediments
, rivers, cliff erosion, marine life
+ Sand com#osition
d) Depositional Shoresd) Depositional Shores
See %ig& ' &'-
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• Spit
• %ay barrier"baymouth bar#
•&ombolo• %arrier island
• 'elta
d) Depositional Shoresd) Depositional ShoresShorelinesShorelines
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Emergent coasts
Develop because of uplift of an area or adrop in sea level
"eatures of an emergent coast ( Wave#cut cliffs ( Wave#cut platforms
e) Emergent and submergent coastse) Emergent and submergent coasts
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)plifted* ancient wave-cut benches e+posed in southern California
e) Emergent and submergent coastse) Emergent and submergent coasts
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Submergent coast
$aused by subsidence of land ad%acent tothe sea or a rise in sea level
"eatures of a submergent coast ( &ighly irregular shoreline ( Estuaries ' drown river mouths
e) Emergent and submergent coastse) Emergent and submergent coasts
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Chesapeake Bay is a goodexample of a submergent coastline
e) Emergent and submergent coastse) Emergent and submergent coasts
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f) Sea-level risef) Sea-level rise
Fossil fuelburning has addedgreenhouse gases toatmos#here
Sea-level rise:
thermal e.#ansion ofseawater and ice,sheetmelting /mm0yr 12,32 cmduring this century
Global warming follows(u# to 2&4 5 in #ast century)