Rivers And Flood Management Book 3

Question 1

Define a flood

Answer 1

When the amount of water in a channel exceeds the capacity of said channel

Question 2

Flooding is natural but what can contribute to its magnitude and frequency?

Answer 2

Human activity

Question 3

What is the name of studying historical records to try to estimate when a dangerous flood will occur?

Answer 3

Flood frequency-magnitude analysis

Question 4

What can hydrologists use historical records to predict?

Answer 4

Th probability of a flood and the risk of extreme 1 in 100 year floods

Question 5

What type of floods are more likely to occur in the future?

Answer 5

High discharge floods

Question 6

Generally speaking, what type of floods occur more frequently?

Answer 6

Lower discharge floods

Question 7

What is flood magnitude?

Answer 7

The severity of a flood

Question 8

Why is flood prediction not very reliable?

Answer 8

Much of it is based on historical data

Question 9

What government agency works in protecting settlements form floods?

Answer 9

The environment agency

Question 10

What are the physical causes of flooding?

Answer 10

1. Excessive prolonged rainfall
2. Intense rainfall
3. Rapidly melting snow
4. Coastal storm surges

Question 11

What are the human causes of flooding?

Answer 11

1. The growth of urban areas
2. Deforestation
3. Climate change
4. Hard engineering

Question 12

What are the physical impacts of flooding?

Answer 12

1. The area of land flooded
2. The amount of sediment deposited
3. Any change to a river’s course

Question 13

What are the human impacts of flooding?

Answer 13

1. Economic cost- householders+insurance companies
2. Economic impact- business+agriculture
3. Economic cost of organising help by government and aid agencies
4. Social impacts such as deaths, homelessness, displacement of people
5. Social impact of health issues

Question 14

Where do the human impacts of flooding tend to be more severe?

Answer 14

Less developed countries

Question 15

Why do the human impacts tend to be greater in LEDCs?

Answer 15

Large numbers of deaths, larger numbers of homeless. Contamination of water supplies. Crops can be ruined, potentially leading to a food shortage. Emergency services cannot cope, reliance on foreign assistance

Question 16

What impacts are most severe in MEDCs?

Answer 16

Economic impacts: insurance claims can be huge, emergency services are trained and equipped well, governments have extra funding to respond in the aftermath of a flood

Question 17

What does flood management seek to reduce?

Answer 17

The frequency of magnitude of flooding and so limit the damage it causes

Question 18

Give an example of where even the most sophisticated flood management has failed

Answer 18

On the Mississippi river when it flooded in 1993 and April and May 2011

Question 19

How did management strategies differ in the more economically developed world and the less economically developed world?

Answer 19

In the MEDW rivers are heavily managed such as the Colorado and Mississippi in the LEDW more limited strategies are used such as on the Ganges in India

Question 20

Give six examples of hard engineering

Answer 20

Dams, embankments, channelisation, channel enlargement, flood relief channels and flood storage reservoirs

Question 21

How do dams reduce the risk of flooding?

Answer 21

They are allow water to be stored temporarily in a reservoir and to manage the rate of flow downstream

Question 22

How do embankments reduce the risk of flooding?

Answer 22

They allow the river channel to carry a greater volume of water

Question 23

How does channelisation reduce the risk of flooding?

Answer 23

It allows water to pass more rapidly along the channel and can involve cutting off meanders

Question 24

How does channel enlargement reduce the risk of flooding?

Answer 24

It increases channel efficiency and reduces roughness and can involve dredging and the removal of large boulders from the riverbed

Question 25

How do flood relief channels reduce the risk of flooding?

Answer 25

They are built when it is too expensive or difficult to modify the existing channel and take excess water around the settlement

Question 26

How do flood storage reservoirs reduce the risk of flooding?

Answer 26

They allow excess water to be stored and can be and can be used for recreational purposes and example would be in Milton Keynes which has been protected from flooding by the rivers Ouse and Ouzel

Question 27

Name six soft engineering strategies

Answer 27

Afforestation, 
agricultural land use management, 
land use only, 
wetland and riverbank conservation, 
river restoration schemes, 
forecasts and warnings

Question 28

How does afforestation reduce the risk of flooding?

Answer 28

Planting trees will slow down the rate at which water reaches the river it is a long-term strategy as the trees take some years to mature

Question 29

How does agricultural land use management reduce the risk of flooding?

Answer 29

Contour ploughing, leaving crop stubble in the ground over winter and strip farming in semi arid areas can help reduce the risk of surface run-off

Question 30

How does Landuse zoning reduce the risk of flooding?

Answer 30

Not building any residential areas on the land at risk of flooding and leaving the grazing all recreational activity so they can flood when necessary

Question 31

How does the wetland on the riverbank conservation reduce the risk of flooding?

Answer 31

Natural River channels and their valleys are protected so that habitats and species diversity can be maintained arable land can be returned to former meadowland that can be flooded on a regular basis

Question 32

How do river restoration schemes lower flood risks?

Answer 32

They return rivers to their original pre-managed states and is more about enhancing the environment and producing flood risk

Question 33

How can forecast and warnings reduced flood risks?

Answer 33

This allows bodies to immediately give advance warnings and advice on evacuation procedures, in LEDCs such as Bangladesh raised concrete shelters have been built so people can be evacuated to a safe place