Coasts

• Beaches

  Beaches form when constructive waves deposit sediment on the shore. Shingle beaches are steep and narrow, whereas sandy beaches are wide and flat, made up of finer material. Features of beaches include berms and ridges found at night tide marks.
• spits

  spits tend to form when the direction of wind changes on the coast. longshore drift deposits sediment across the river mouth, parallel to the coastline, this is a simple spit. when the wind changes direction the end of the spit can curve, when the head of the spit has a recurved end this becomes a compound spit. the area behind the spit is sheltered and low energy, therefore develops into mudflats or lagoons.
• bars

  bars are formed when a spit joins two headlands together, this can be in the mouth of the river or in a bay. a lagoon forms behind the bar. bars can also form off the coast, when material moves towards the coast- these are partly submerged by the sea, therefore they are called offshore tombolos. a bar that connects the shore to an island is called a tómbolo.
• wave cut platform


  the sea erodes the land, causing the cliff face to retreat due to hydraulic action and weathering. this causes a wave cut notch to form at the high water mark, eventually forming a cave. the rock above the cave becomes unstable overtime, causing the rock to collapse. wave cut platforms are left behind when the cliff is eroded.
• barrier islands

  barrier islands are long narrow island of sand that are detached from the coastline and sit parallel to it. they form in areas with a good sediment supply, powerful waves and a small tidal range. lagoons form behind barrier islands as they are low energy environments and sheltered. they were initially bars that have been eroded in sections and eroded away from the coastline.
• sand dunes

  sand dunes form when sand is deposited by longshore drift onto the coastline. a process called aeolian sands transports the sand up the beach. the sand is trapped and stabilised by vegetation, and colonised by plants and grasses. overtime more sand is trapped increasing the sizes of sand dunes, dunes also migrate up the beach, leaving room for new embryo dunes to form.
• mudflats and salt marshes

  They form in sheltered, low energy environments. Form when silt and are deposited by the river, and overtime mudflats form. These mudflats are colonised by vegetation, which trap more mud and silt that builds up to overtime become more exposed as a salt marsh. This vegetation is able to survive long periods of time submerged in salty waters Of the tide.
• rias

  rias are formed when river valleys are partially submerged. they have a gentle long and cross profile. they are wide and deep at their mouth and become narrower the more inland they reach.
• fjords


  fjords are drowned glacial valleys, that are straight and narrow with very steep sides. they have a shallow mouth with a raised area called the threshold formed by deposition of glacial material. they become deeper further inland.
• Dalmatian coastlines

  Valleys lie parallel to the coastline, when these valleys are flooded it leaves islands parallel to the coastline.
• raised beaches 


  Formed when the fall in sea level leaves beaches above the high tide mark, therefore overtime sediment on the beaches becomes colonised by vegetation and develops into soil.
• mass movement

  mass movement is the shifting of material downwards due to gravity. types of mass movement includes slumping, sliding, rockfall and mudflows. unconsolidated rocks are more likely to fall due to there being less friction to hold them together. heavy rain can saturate this unconsolidated rock, further reducing the friction, making it more likely to collapse. run off can erode fine particles, causing them to move downslope.
• Mekong delta opportunities

  Population=17 million

  provides 33% of vietnams GDP

  has an economic growth of 7.6%

  provides 50% of vietnams rice production

  GDP per capita= $2700

  home to 70% of vietnams aquaculture
• Mekong delta- challenges

  flood hazards- upstream there is discharge and downstream sea level change.in 2000 a 50 year flood led to the country losing $200 mill

  by 2100 Mekong could lose 38% of its land due to erosion and flooding

  there are trans boundary conflicts- for example the use of hydropower upstream is decreasing soil fertility downstream.

  wetland drainage- sea level rise- flooding is leading to saltwater intrusion which is damaging rice paddies.

  population increase means flood management has potential to fall
• how is the mekong delta planning to create coastal resilience

  -receive $300 mill from the world bank- to invest into education and flood management strategies

  -the Netherlands are supporting this investment and are advising the Vietnamese se government on how to successfully achieve coastal resilience as they have got experience in coastal erosion But have mitigated.

  -Mekong river commission- set up to manage trans boundary issues
• Explain the concept of a sediment cell

  A closed system usually bounded by headlands or longshore drift. Within a sediment cell there is erosion, transportation and the deposition of sediment within a cycle. Inputs are the sediment caused by the erosion of the sea bed or land. There is little or no movement of sediment between cells. Human activity such as beach management can cause an imbalance of sediment within the cell leaving an area vulnerable to erosion.
• Positive feedback

  Sea level rise- more of the coastline is submerged- higher wave attack- more undercutting takes place- coastline retreats

  temps rise- ice melts- sea is more exposed to sun- less albedo affect- sea absorbs more heat-more ice melts