Coastal processes Flashcards
Waves
Most waves are formed by wind blowing across the surface of the sea or other large body of water. The friction between the wind and the surface of the water causes the water to move in a circular motion. Although the wave moves forward, the water does not move with it. As the wave moves into shallow water, it breaks. When the depth of the sea is less than the height of the wave, friction with the bottom increases and the wave slows down. The wavelength becomes shorter and the front of the wave becomes steeper. The top of the wave then tumbles forward. When this happens, the wave is said to break.
Wave erosion
Hydraulic Action: Waves can hit the coastline with a great deal of force. The force with which waves hit the coastline is often enough to cause erosion.
Abrasion/ corrasion: The material carried by the wave is thrown against the coast, thereby eroding it.
Attrition: Small stones and other material carried by the wave are thrown against each other. They are further broken down and worn into a round shape.
Solution: Sea water dissolves soluble minerals in the rocks on the coastline.
Cliffs/wave cut platforms
A cliff is defined as a steep rock face. Where marine erosion is powerful, the coastline is eroded to form a cliff. Erosion is concentrated at sea level. A notch is cut in the rock at the level where wave attack is concentrated. When the notch is cut too far, the area above this notch collapses forming a cliff.
Headlands and bays
headlannd- a section of rocky coastline that protrudes into the sea
bay- a pronounced indentation in the coastline usually found in between two headlands.
Long-shore drift
The transport of sand and pebbles along the coast.
Spits
These are formed when material is deposited along the coastline by longshore drift
Tombolo
This is a linear deposit of material formed by longshore drift which joins an island to the mainland.
Coral reef definition
A coral reef is an offshore ridgeoro formed from the secretions of small marine animals called coral polyps.
types of coral reefs
barrier reefs, fringing reefs and atoll
Fringing reef
is a shallow water features found close to and parallel to the shore. it forms from the gradial accumulation of coral to the coast. Over time, storms and marine erosion move the coral to form the irregular coral platforms.
barrier reef
lies in deeper water, much further to sea. develops near low living coastal plains. a rise in sea levels floods the coastal lowland, creating a wider body of water. coral continues to grow to form a large barrier feature that is now separated from the coast.
atoll reef
is an isolated ring-shaped week rising our of deep water.
conditions coral favours
Temperature- the water should be warm. most corals thrive in temperature 21 and 30 degrees celsius.
depth-coral feed on algae which need light to photosynthesize and grow, if there is not enough light there will be no algae.
salinity-corals thrive in salty water .The water should contain the right amount of salt. Coral will not grow in areas where a large amount of fresh water pours into the sea.
Benefits of coral reefs
Reefs provide a home for many species of marine life including sponges, algae, sea urchins, shellfish and fish.
Many tourists visit tropical areas to visit coral reefs.
Problems coral reefs face
overfishing
ecological damage(tourism)
benefits of mangrove wetlands
coastal protection- the dense tangle of mangrove roots help to trap sediment.
socio-economic benefits- mangrove swamps are tourist attractions and provide raw materials for many human activities.
definition of a bar
is a long narrow deposit of sand or shingle that forms across a bay, often trapping freshwater behind it
spit
is a narrow finger of sand and pebbles that juts out.
landforms of coastal deposition
beaches
spits
tombolos
bars
ITCZ - inter tropical convergence zone
is a low pressure belt of very unstable weather that forms of the boundary of the two hadley cells.
Hydrolysis
is a chemical weathering process that occurs in rocks rich in minerals. e.g sodium. The minerals come in contact with water forming a solution which changes a chemical composition of the rock.This makes the rock weaker which causes it to break down.
Explain two ways in which agriculture contributes to degradation of coral reefs
Pesticides and fertilizers from crops run off the land and into bodies of water when it rains. When these chemicals enter the water, they destroy coral reef ecosystems by harming creatures such as zooplankton, a vital organism for various species
Loose soil from agriculture can run into the water causing the waters to become muddy which can prevent sunlight causing the coral reefs to die.
Discuss two measures that have been implemented at the national level of most countries to ensure the sustainability of coral reefs .
Protected areas like barrier reef that is a world heritage site and protected by the government
Laws and legislations in bermuda have prevented overfishing to protect coral reefs.
Features of an atoll reef
circular or oval in shape
forms around a deep lagoon
Features of a fringing reef
separated from coast by a shallow lagoon
linear coral platform
Two reasons why corals grow best in clear water
clear water allows algae cells to grow from photosynthesis allowing corals to feed on them and clear water has sufficient oxygen levels for corals.
For a named Caribbean country assess the value of any two measures that have been used by national agencies to reduce the impact of flooding
paved drains- makes it less likely for river to flood as it holds water
Trinidad-sea wall-reduce flooding in coastal areas
Explain how a flood plain is formed
When rivers start to meander, curving from side to side, the water erodes the banks of the river and creates a wide flat area around the sides.
