Unit 4 : Rivers Flashcards
What is sustainability ?
Sustainability consists of fulfilling the needs of current generations without compromising the needs of future generations, while ensuring a balance between economic growth, environmental care and social well-being.
Hard engineering with examples
Hard engineering involves building artificial structures, which try to control natural river processes at a local scale. Examples include : sea walls, rock armor, gabions and groynes
Sea walls ( definition )
Concrete walls that are placed at the foot of a cliff to prevent erosion. They are curved to reflect the energy back into the sea.
Sea walls ( adv and dis )
Advantages
Effective at protecting the base of the cliff.
Sea walls usually have promenades so people can walk along them.
Disadvantages
Waves are still powerful and can break down and erode the sea wall.
Expensive - approximately £2,000 per metre.
Ugly
Rock armor ( def )
Large boulders placed at the foot of a cliff. They break the waves and absorb their energy.
Rock armor ( adv and dis )
Advantages
Cheaper than a sea wall and easy to maintain.
Can be used for fishing.
Disadvantages
They look different to the local geology, as the rock has been imported from other areas.
The rocks are expensive to transport.
Gabions ( def )
Rocks are held in mesh cages and placed in areas affected by erosion.
Gabions ( advs and dis )
Advantages
Cheap - approximately £100 per metre.
Absorbs wave energy.
Disadvantages
Not very strong.
Looks unnatural.
Groynes ( def )
Wooden or rock structures built out at right angles into the sea.
Groynes ( adv and dis)
Advantages
Builds a beach - which encourages tourism.
They trap sediment being carried by longshore drift.
Disadvantages
By trapping sediment it starves beaches further down the coastline, increasing rates of erosion elsewhere.
They look unattractive.
Soft engineering
Soft engineering does not involve building artificial structures, but takes a more sustainable and natural approach to managing the coast
Beach nourishment ( def )
Sand is pumped onto an existing beach to build it up.
Beach nourishment ( adv and dis )
Advantages
Blends in with the existing beach.
Larger beaches appeal to tourists.
Disadvantages
Needs to be constantly replaced.
The sand has to be brought in from elsewhere.
Reprofiling ( adv and dis )
Advantages
Cheap and simple.
Reduces the energy of the waves.
Disadvantages
Only works when wave energy is low.
Needs to be repeated continuously.
Reprofiling def
The sediment is redistributed from the lower part of the beach to the upper part of the beach.
Dune nourishment (def)
Marram grass planted on sand dunes stabilises the dunes and helps to trap sand to build them up.
Dune nourishment ( dis and adv )
Advantages
Relatively cheap.
Maintains a natural-looking coastline.
Disadvantages
Can be damaged by storm waves.
Areas have to be zoned off from the public, which is unpopular.
erosion 4
hydraucolic action, attrition, abrasion, corrosion
transportation 4
traction, saltation, suspension, solution
how do dams help prevent flooding
dam buiding can reeduce teh amount of water flow, if there is a possibility of flooding, sluices in the river can be closed so that some wtaer will remain behind in the resevoir
three gorgers dam location
huebi province, yangteze river
when did constrcution begin and when did it end
1994,2008 (reach full electriity production capacity in 2012)
cost (dam)
accoridng to chinease officials it cost 24 B hwover outside sources sya it coudl be upto three times thiks cots. funding came from government funds and other bonds
ecpnomic benifts of the dam (5)
- help china produce it own energy
- reduce reliance o oil from other countries
- less economic lossses from the floods
- positivly impact tourism becasue more scenic routes are now accessable
- larger ships can transport products opeing the region to inceased tarde
social consequnces 4
- displced more people than the three preivous largest chinese dams combind
- nearly 13 cities, 140 towns and 14000 villages destroyed
- 1.4 million peple displaced
- protects over 100 million people fruther downstream
envirnemntal impacts 5
- reduces cola consumption by upoto 31 million tonnes annually
- 80% of teh land is experiancing problems with erosion
- (produces over 40 million tonnes of sediment that is deposited into teh river each year)(the sediment places weight on teh seismic fault the dam happpens to sit on)
- the river contains over 300 fish species, teh dam prevents fishes from spawning upstrem and so diminishes population iszes
- 100,000 acres were flooded (accoounted for 10% of chinas grain supply)
what could have been done instead of teh dam
