1.2 Hard and Soft Engineering

Question 1

What is the 3 Gorges Dam?

Answer 1

• Built to prevent natural processes and protect land and property, confining and controlling water.
• It was built in 1994 and finished in 2009
• There was a long history of flooding on the Yangtze River.
• Aimed to reduce risk, provide power and navigation.
• In 1991 3000 killed in flood and 1998 40,000 killed - 14m displaced and farming was done out.
• Created 660km reservoir, 1km wide.
• Dam is 2km long and 100m high
• Cost £25bn

Question 2

What are the successes of 3 gorges?

Answer 2

• HEP for 13m people
• Reduced risk to 15m people
• Protects 1 in 100 year floods
• Hasn’t been breached
• Protects 50m people (pop growth)
• Millions of ha of farmland and irrigation channels made
• 13m get electricity and water in Shangai
• Provides 10% of China’s electricity - eco friendly 18000MW of HEP
• Large ships can navigate areas boosting development

Question 3

What are the failures of the 3 gorges?

Answer 3

• Suffers from EQs
• resettlement of 1.2m
• Sediment content fell causing erosion downstream and accumulation behind dam.
• Afforestation on slopes to redce sediment washed into the river
• Historical monuments lost
• Increased landslides, habitats lost, pollution, soil lost.

Question 4

What was done at Nottingham Trent?

Answer 4

Natural flood embankments made, protecting 16,000 properties over a 15 mile stretch. Flood walls also built on the Trent

Pros: natural, fits into environment, increases capacity, makes floods less likely.
Cons: expensive, takes up lots of space, ugly, increases speed so can cause downstream erosion.

Question 5

What was made at the Thames, Exe and Ravensbourne?

Answer 5

Ravensbourn - straightened with concrete however caused worse flooding downstream which was unsafe and unsuccessful so the scheme was removed. Was successful in preventing flooding however was ugly, expensive and unsafe

A flood barrier gate was made in the Thames to prevent estuary sea water from coming up in high tide

Exe: diversion spillways created 3 flood alleviation channels running parallel. Cost £8m, was a significant storage area which could withstand 7 cumec flows, still working. It is long lasting and effective and takes up lots of space - can’t be done everywhere

Question 6

What was the quaggy restoration scheme?

Answer 6

Artificial channels and culverts were built in 60s to divert in beneath the ground through Greenwich due to flood risk and urban developing. The EA decided to follow a more sustainable approach

• Improved local environment
• brought water above ground again
• cut new channel through park creating open space
• improved park quality
• culvert remained in times of flood
• park lowered and shaped, creating floodplain where water collects naturally
• stores 85k cm^3 of water
• Reduced risk to 600 buildings and created a diverse environment.

Question 7

What was done on the river Skerne?

Answer 7

• Straightening and deeping for flood control and drainage
• Floodplain raised above river and waste tipping occupied by housing, gas and sewage pipes and electricity cables - degraded area
• Restoration project restored 2km of Skerne, improving habitat diversity, water quality, landscape and access for the community. This involved:
• Re-meandering the course of the river
• Reprofiling the bank to give natural shapes
• Lowering floodplain to store water
• Shallow flooding allowed to help remove silt
• Footpaths

This has created natural pool/riffle sequences and water quality, biodiversity and environment has improved.