Flashcards in Uk coastal landscapes Deck (42):
What are the two types of wave called?
constructive and destructive
How do waves form?
Transfer of energy and wind
what does the energy of a wave depend on?
-The distance the wind has been blowing
-The speed the wind is travelling
-The length of time the wind has been blowing
what are the features of a destructive wave?
-Occur in stormy conditions
-Probably travelled a long distance (large fetch)
-Responsible for erosion
-Have a greater backwash than swash
What are the features of a constructive wave?
-Occur in calm conditions
-help transport material by longshore drift]-responsible for deposition
-have a greater swash than backwash
what are the three types of weathering?
Mechanical, mass movement and chemical weathering
what is mass movement
the downhill movement of material under the influence of gravity
what do the different types of mass movement depend on?
-amount of water in the material
-mature of the movement (falls, slips or rotational slides)
what is freeze-thaw?
when it freezes water in the cracks of a rock expand. Over time the crack widens and pieces of rock fall off
when does chemical weathering happen?
when the rocks mineral composition is changed
what are the processes of coastal erosion?
Hydraulic power, abrasion, attrition and solution
what is solution?
seawater causes some rocks, especially limestone, to gradually dissolve.
what is attrition?
rocks and pebbles carried by waves rub together and break down into smaller pieces
what is abrasion?
during storms breaking waves throw sand,pebbles and boulders against the coast
what is hydraulic power?
the weight and impact of water against the coastline erodes the coast
explain longshore drift
1)waves approaches the coast at an angle
2)swash pushes sand and gravel up the beach at the same angle.
3)backwash carries sand and gravel back down the beach at 90 degrees tot he coastline under the force of gravity
4)sand and gravel move along the beach in a zigzag fashion
5)sand is lighter than gravel so moves further up the beach
what are the factors affect deposition?
-sheltered spots (bays)
-gentle gradient offshore, causing friction
draw the diagrams showing
-formation of a wave
-formation of headlands and bays
-hard rock coastal landform created by erosion (caves, arches and stacks and wave cut platforms)
how are curved beaches formed?
waves refracting or bending as they enter a bay
what is a shingle beach?
beaches that are sandy or pebbly
where are shingle beaches usually found?
where cliffs are being eroded and where waves are powerful
what are spits
narrow projections of sand or shingle that are attached to the land at one end. They extend across a bay or estuary or where the coastline changes direction.
how are spits formed?
longshore drift powered by a strong prevailing wind
how do bars differ from spits?
bars grow right across the bay, cutting off the water to form a lagoon
what is a sea wall? (hard engineering)
sea walls are made of concreate; the curved face on some sea walls are designed to reflect wave energy
how much does it cost to build a sea wall per meter
name a positive and negative of a sea wall
+reliable protection for buildings and cliffs
-very expensive to construct and maintain
how is rock armour used? (hard engineering)
rock armour uses big blocks of highly resistant rock to absorb wave energy
how much does rock armour cost per metre?
name a positive and negative of using rock armour?
+quick to build and easy to maintain
-often looks messy; blocks often need to be repositioned
what are Gabions? (hard engineering)
wire baskets filled with stones; they are only used on sandy beaches: wave carrying shingle would quickly break them
how much does it cost to build gabions per metre?
name a positive and negative of gabions
+cheap and easy to construct. any stones can be used to fill the cages
-the cages can rust and break; broken cages have sharp ,rusty, dangerous edges
how much are groynes? (hard engineering)
5000 each (spaced at 200m)
name a positive and negative of groynes
+widen the beach: good fro tourism
-longshore drift moves sediment all along the coastline so groynes on one beach prevent sediment reaching others
what is beach nourishment? (soft engineering)
material is dredged from the sea or brought from other beaches to an eroded beach
name a positive and negative of beach nourishment
+widens the beach: good for tourism
-has to be repeated year after year
what is beach reprofiling? (soft engineering)
material form the lower part of the beach is moved to the upper part, where it provides better protection
name a positive and negative of beach reprofiling
+improves protection of seafront property
-can be difficult fro tourists to get down a steep upper beach of recreation
what is dune regeneration? (soft engineering)
can involve creating new dunes
how much does dune regeneration cost per 100m?