Flooding

Question 1

What are the 3 issues related to flooding? (10 markers)

Answer 1

1. Impact on human activities
2. Human activities increasing the likelihood of flooding
3. Physical factors affecting the likelihood of flooding

Question 2

What 5 physical factors increase flood risk?

Answer 2

1. rock type
2. relief
3. drainage regime
4. climate
5. vegetation

Question 3

What 5 human factors increase flood risk?

Answer 3

1. urbanisation/ settlement location
2. farming
3. deforestation
4. drainage
5. climate change

Question 4

Physical -

rock type

Answer 4

permeable = increased risk of flooding

• eg. shale/clay
• natural storage of groundwater + can store rain water
• decreased runoff

Question 5

Physical -

relief

Answer 5

1. upland areas intensify rainfall and orographic rainfall is more likely to occur
2. steep slopes cause rapid runoff, decreases lag-times and increases peak flows = increased risk of flooding

Question 6

Physical -

drainage regime

Answer 6

eg. natural presence of vegetation aids drainage through interception and evapotranspiration

Question 7

Physical -

climate

Answer 7

1. Prolonged rainfall –> saturated ground = BUT more predictable so allow early warning systems
2. Intense rainfall –> heavy convectional rainfall associated with thunderstorm cells causes flash floods
3. monsoons/ seasonal melting of glacial icecaps

Question 8

Physical -

vegetation

Answer 8

• intercepts rainfall + evapotranspiration

- reduces runoff

Question 9

Name 3 extra physical factors that can cause COASTAL flooding.

Answer 9

1. high tides
2. low lying areas
3. storm surges

Question 10

Physical (coastal) -

high tides

Answer 10

1. spring tides occur twice a month

Question 11

Physical (coastal) -

low lying areas

Answer 11

eg. deltas/ estuary/ marshland

eg. bangladesh = 25% less than 1m above sea level

Question 12

Physical (coastal) -

storm surges

Answer 12

eg. Hurricane Sandy, NYC, 2012

Question 13

Human -

urbanisation

Answer 13

• building on floodplains
• disrupts hydrological cycle
• increases impermeable surfaces
• increases runoff
• increases speed at which water can travel = short lag time = high peak flow

Question 14

Human -

farming

Answer 14

1. replacing pasture with arable crops leaves little plant cover for half the year = reduced evapotranspiration/ transpiration
2. unsustainable farming practices like over-cultivation = soil erosion = siltation of rivers = reduces channel capacity = increased likelihood of flooding

Question 15

Human -

deforestation

Answer 15

1. less trees = reduced evapotranspiration/ transpiration

2. less trees = soil erosion = siltation of rivers = reduces channel capacity = increased likelihood of flooding

Question 16

Human -

drainage

Answer 16

eg. french drains

Question 17

Human -

climate change

Answer 17

1. rising sea levels
   - eg. bangladesh = 25% less than 1m above sea level
2. increased intensity of climatic hazards (eg. hurricanes in tropical latitudes and depressions in mid-latitudes)