Assessment 1 - Autumn 2023

Question 1

Explain the concept of positive feedback with reference to the water cycle. (4 marks)

Answer 1

• Positive feedback cycle amplifies change in a system
• An increase in global temperatures, increase melting of ice caps
• Melting of ice caps releases Co2, a greenhouse gas
• An increase in Co2, contributes to the enhanced greenhouse gas effect, which amplifies the melting of ice caps

Question 2

Describe the different ways that water can enter a river channel. (4 marks)

Answer 2

• Precipitation can directly enter a river channel
• Precipitation can infiltrate into the soil if it isn’t saturated or porous. This can enter a river channel via throughflow when the soil is saturated/permeable
• If the soil is fully saturated, percipitation can not infiltrate and cause surface run-off, reaching a river channel
• Water can percolate from the soil to the rock if permeable and can reach a river channel via groundwater flow

Question 3

Explain the concept of carbon sequestration. (4 marks)

Answer 3

• Carbon sequestration is the natural or artificial capturing of carbon which is stored in solid or liquid form
• The aim is to remove carbon from the atmosphere, thus reducing human induced contribution to Co2 and the resultant increased trapping of solar radiation and global warming
• An example of artificial carbon sequestration involves capturing carbon from coal-fired power plants
• The captured Co2 is then piped underground and stored in rock strata porous enough to hold Co2

Question 4

Contrast the two hydrographs in Figures 2b and 2c. Suggest reasons for this contrast using evidence from Figure 2a. (6 marks)

Answer 4

• Clapham Beck has a longer lag time than Austwick Beck
• Figure 2a shows Austwick Beck in impermeable sandstone, surface run-off, short lag time
• Clapham Beck is in permeable limestone, long lag time due to interception
• Austwick Beck has few trees
• Greatest influence is geology

Question 5

Using Figure 2 and your own knowledge, assess the natural and human induced causes of the 2005 flood in Carlisle. (6 marks)

Answer 5

• One natural factor is geology (e.g. permeable and impermeable rocks)
• Impermeable rocks have a high risk flood, more surface runoff
• One human factor is urbanisation. Reduces ability of land to absorb rainfall in impermeable surfaces, more surface runoff