Flood Management

Question 1

What is flood management?

Answer 1

Flood management is the use of engineering schemes to try to reduce the magnitude and or frequency of flooding.

This aims, ultimately, to reduce the damage caused by flooding.

Question 2

What are the two main engineering strategies for flood management?

Answer 2

1. Hard Engineering - this aims to use large scale engineering schemes to modify the flood of water through the river basin.
2. Soft Engineering - this is concerned with flood obatement through changing land use in upstream areas of river basin. Term so holistically meaning they look at the whole river.

Question 3

What are embankments?

Answer 3

Hard Engineering

They are artificial levees

• Increase capacity of the river
• Raising banks of the river
• Increasing bank full discharge

Question 4

What is river straightening?

Answer 4

Hard Engineering

Also known as channelisation.

• Straightens meanders which speeds up river flow in flood prone areas.

Question 5

What is a diversion spillway?

Answer 5

Hard Engineering

• Artificial channels that a river can flow into when it’s discharge rises.
• Moves water away quickly.

Question 6

What is a flood barrier?

Answer 6

Hard Engineering

It is a specific type of floodgate designed to prevent a storm surge or Spring tide from flooding an area.

Question 7

What is channel enlargement?

Answer 7

Hard Engineering

It is when the width and depth of a river is increased, which increases its cross sectional area.

Question 8

What is a dam?

Answer 8

Hard Engineering

Concrete and steel dams block rivers and cause the water to back up and flood the valley.

Water is released and the flow is controlled.

Question 9

What is flood proofing?

Answer 9

Soft Engineering

• Raising properties above flood level (elevation).
• Sealing properties so that flood water cannot get in.

Question 10

What is floodplain zoning?

Answer 10

Soft Engineering

• Areas closest to rivers are only used for low cost uses
  , such as playing fields and grazing.

Question 11

What is managed flooding?

Answer 11

Soft Engineering

• Ecological flooding
• River is allowed to flood naturally in some areas to prevent flooding in other areas.

Question 12

What is afforestation?

Answer 12

Soft Engineering

• When plants and trees are planted along the river.
• This means that there is greater interception, evapotranspiration and take up from roots.

Question 13

What are flood warning systems?

Answer 13

Soft Engineering

• Sirens that give people an early warning of a possible flood.
• TV, radio, email, fax and text messages also used.

Question 14

Why was the Three Gorges Dam in China built?

Answer 14

• to reduce the season of flooding that takes place along the Yangtze River.
• 1998 flood killed over 3500 people
  Left 13 million people homeless
  Caused billions of dollars of damage

Question 15

What are the economic impacts of the Three Gorges Dam?

Answer 15

• £1.1 billion to build
• Took almost a decade for the dumb to pay for itself by hydroelectric power
• increased trade capacity on the river
• reduced China’s dependency on coal meaning they do not have to spend as much

Question 16

What are the political impacts of the Three Gorges Dam?

Answer 16

• forced relocation 1.2 million people, raised human rights concerns
• The World Bank refused to fund the project due to environmental and social impact
• The dam is now a major military target, leaving some of China’s largest cities including Shanghai at risk

Question 17

What are the social impacts of the Three Gorges Dam?

Answer 17

• people who refused to relocate were forcibly removed from their homes
• over 13 cities and hundreds of villages were flooded
• those displaced lived on $1 or less per day
• hundreds of cultural relics, archaeological sites and family burial grounds were flooded

Question 18

What were the environmental impacts of the Three Gorges Dam?

Answer 18

• sediment is now stuck and blocked behind the dam
• engineers letting some sediment through, leads to the gradual destruction of the Delta
  Increase erosion downstream of the dam
• The block to sediment also is the chemical composition of the water upstream, leading to a reduction in biodiversity and the potential extinction of several species of animals
• as the river is the main dumping ground for industrial and household waste the waste will collect behind the dam and poison the water behind it
• destruction of habitats
• soil becoming less fertile as a reduction in flooding, this means artificial fertiliser is used which drains in to the river and pollutes it down stream