River Flooding & Management AQA

What are the physical reasons for flooding?

• Urbanisation

• Impermeable geology

• Small drainage basin

• Prolonged rainfall

• Deforestation

Which of the following are human reasons for increased risk of flooding?

• Urbanisation

• Deforestation

• Afforestation

• Changes in farming practices

• Steep valleys

The following image shows a hydrograph, but what factors would increase the lag-time (the difference between peak rainfall and peak discharge)? Tick all relevant answers.

• More vegetation cover in a drainage basin.

• Increased urbanisation.

• Deforestation.

• Permeable geology.

• Saturated soil.

Hard engineering involves the use of artificial structures which physically alter the river channel to protect areas from flooding, but which of the following are examples of hard engineering?

• Dams and reserviors

• Flood relief channels

• Tree-planting

• Flood-plain zoning

• Embankments

Soft engineering involves adapting and working with natural river processes, but which of the following are examples of soft engineering?

• Flood warnings

• Flood relief channels

• Tree-planting

• Flood-plain zoning

• Creation of wetlands / washlands (flood storage areas)

What are the advantages of hard engineering strategies such as flood relief channels?

• Reduced flood risk for immediate area which has been protected.

• Works with natural processes therefore is more sustainable.

• Increased flood risk downstream.

• House values in protected area increased

• Some flood relief channels are built to look natural and have meanders and reed beds.

What are the advantages of planting trees as a soft approach to manage rivers?

• Increased interception

• Reduced surface-runoff

• Expensive

• Creates new wildlife habitats.

• Loss of grazing land for animals.

Draw a hydograph