Coastal Systems and Landscapes Flashcards
What is the main use of land in Bangladesh
Farming and agriculture, as well as rural fishing and farming practices
What are some challenges and threats along the Bangladesh coastline
Physical geography - the ground tends to be low lying, making it susceptible to floods
Also threatens the soil used for farming as sea water flooding will create inundation
Deforestation - much of the land is used for agriculture, and forests are cleared to make more room. Poor enforce-ability on deforestation laws means the soil is to become weaker and unable to hold itself together from the loss of roots –> leeching
Coal power station of the mangrove coast - mangroves are removed, so less of a natural barrier against storm surges and more plants will die as there’s more salt in the water.
what are some ICZM actions that have taken place along the Coastline of Bangladesh
- 2,000 cyclone shelters have been built, serving 27% of the coastal population
- 1,500 raised mounds constructed as it was realised livestock needs to be saved in order for people to have a reliable income after the storm hits
- storm shelters are multi use and also act as schools and social centres
How many people is the Sundarbans home to
3 million people
Describe the physical landscape of the Sundarbans
- made up of chars, deltas and khals
- a tropical estuarine ecosystem
- lots of halophytic trees/shrubs –> mangroves
- dynamic areas where sediment thats transported by rivers are loaded off due to the river incapacity to carry the sediment
- large percentage of the world’s population live in these areas due to their proximity to the sea, which is useful for fishing practices and travelling via boat
How do people make a living whilst living in the Sundarbans
- fishing for valuable fish, shrimp, mollusks etc
- food and drink can be sourced from the mangrove forests such as salts, oils, honeys and fruits
- fuel can be found through charcoal and firewood
- organic matter makes the soils very fertile, meaning the lands in the mangrove forest or surrounding can be used for agricultural practices and farmland for livestock -> profit
How do mangroves provide protection for people living in the Sundarbans
- they act as a natural buffer against storm winds, floods and storm surges, as well as reinforcing land that is susceptible to coastal erosion
- it is said that the density of 30 trees per 0.01 hectare can reduce the destructive force of a tsunami by up to 90%
What are some natural challenges surrounding the Sundarbans
- instability of the islands
- cyclones
- coastal flooding
- high levels of salinity in the soil
What are some human challenges surrounding the Sundarbans
- over exploitation of coastal resources from vulnerable habitats
- conversion of wetlands to intensive agriculture and settlements
- destructive fishing techniques
- lack of awareness of the environmental and economic importance of the region
Outline the major subsystems of the Earth and what they are
Lithosphere - the crust and upper mantle of the earth that consists of the hard rigid outer layer of the Earth
Hydrosphere - a discontinuous layer of water at the earth’s surface, including all liquid and frozen surface waters, groundwater and water in the atmosphere
Biosphere - the total sum of all living matter, and the biological component of earth’s systems
Atmosphere - the air that surrounds the earth, made up of gases and water vapour
What is an isolated system
no input or output of energy or matter, an example being the universe
What is a closed system
there is inputs, transfers and outputs of energy, but not of matter
What is an open system
there are inputs, outputs and transfers of energy and matter
how are waves formed
as air moves across the water, frictional dag disturbs the surface and forms ripples or waves
characteristics of constructive waves
strong swash, weak backwash
usually associated with a gentle beach profile
low, surging waves with long wave lengths
beach GAIN (inputs exceed outputs)
Characteristics of destructive waves
weak swash, strong backwash
usually associated with steeper beach profiles
high, plunging waves with short wave lengths
beach LOSS (outputs exceed inputs)
what is the wavelength of constructive waves
up to 100M
what is the wavelength of destructive waves
generally less than 12M
what is wave refraction
the change in direction of a wave as a result of traveling at different speeds at different points along the wave front
what is a tide
the periodic rise and fall of the level of the sea in response to the gravitational pull of he sun and the moon
name the three kinds of currents and what they do
longshore currents - most waves do not hit the coastline ‘head on’, and so approach at an angle. this generates a flow of water running parallel to the coast (longshore drift)
rip currents - strong currents moving away from the shoreline, and they develop when sea water is piled up along the coastline by incoming waves
upwelling - movement of cold water from deep in the ocean towards the surface. the more dense cold water replaces the warmer surface waters and creates nutrient rich cold ocean currents
low energy coastline features?
constructive waves with low energy
the rate of deposition often exceeds the rate of erosion
typical landforms include beaches and spits
Example: the baltic sea
high energy coastline features?
strong, steady prevailing winds that create high energy waves
rate of erosion exceeds the rate of deposition
typical landforms include headlands, cliffs and wave-cut platforms
Example: Cornish Coast of southwest England
what are geomorphological processes (there are 2)
marine - operate upon a coastline and are connected with the sea, such as waves, tides and longshore drift
sub-aerial - includes processes that slowly break down the coastline, weaken underlying rocks and allow sudden movements or erosion to happen more easily –> acts as a catalyst
what is weathering
breakdown or rock at or near the Earth’s surface creating regolith that remains in situ until it is moved later by erosional processes.
it can be biological, chemical or mechanical
.
what is erosion
the wearing away of the earth’s surface by mechanical action
what is transportation
the process that moves material from the site where erosion took place to the site of deposition
what does mass movement depend on
- the level of cohesion within the sediment
- the height and angle of the slope
- the grain size within the sediment
- temperature and level of saturation
what are strata
layers of rock
whats a bedding plane
horizontal. natural breaks in strata
whats a joint
vertical fractures
whats a fold
folds formed by pressure during tectonic activity
whats a fault
faults formed when the stress of pressure to which a rock is subjected, exceeds its internal strength
what are some ways to describe a cliff profile
faults, folds, strata, joints and bedding planes
what rocks are hardest to erode
igneous e.g. granite, pumice
what rocks are easiest to erode
sedimentary e.g. sandstone, chalk
what does concordant and disconcordant coastline look like
Concordant coastlines have the same type of rock running parallel to the coast, while discordant coastlines have alternating bands of hard and soft rock that are perpendicular to the shore
what does an emergent or submergent coastline look like
An emergent coastline appears as land that has risen above the water level, often with features like raised beaches, exposed rocky platforms, and cliffs, while a submergent coastline looks like a drowned landscape with flooded river valleys, bays, and estuaries,
factors that govern the characteristics of coastal landscapes
high vs low energy
erosion vs deposition
more or less intensively managed
geology
outline the sequence in the development of a wave cut platform (4)
These are often found along high energy where erosion outweighs deposition (1)
The process starts with hydraulic action and abrasion by sea waves striking against a headland which carve out joints and bedding planes (1)
Over time the cliffs becomes undercut, creating a notch
Once the north becomes large enough the over lying rock falls too heavy as it becomes too heavy, and so it collapses.
