1.7. Water Cycle Changes

Question 1

Evidence of storm events affecting the water cycle

Answer 1

Storm Desmond in 2015 dumped 262mm of rain into the River Eden basin in Cumbria over just 48 hours, resulting in widespread flooding of 2000 properties in Carlisle.

Question 2

How do storm events affect change in the water cycle?

Answer 2

Intense storms generate more precipitation and greater peak discharge than light rain

Large input causes flows and stores to increase in size

Question 3

Counter argument for storm affecting change in water cycle

Answer 3

Some flows like infiltration may not be able to occur rapidly enough, resulting in increased runoff

Question 4

Evidence for seasonal changes affecting change in water cycle

Answer 4

• Infiltration may reduce due to frozen ground and closed up soil pores
• Deciduous leaf growth in spring/ summer increases interception storage and slows movement of water to river

Question 5

How do seasonal changes affect change in the water cycle?

Answer 5

• In Winter, temps may drop below freezing and certain flows may significantly decrease whilst frozen water stores increase. Temp increases may then increase flows as ice begins to melt.
• Most plants show seasonal variation. The more vegetation there is in a drainage basin, the more water that’t lost through evapotranspiration, reducing runoff and peak discharge.

Question 6

Evidence for glacial and interglacial change affecting change in water cycle

Answer 6

• Milankovitch cycles- cycles orbit changes every 100,000 years
• Glacial- sea levels over 100m lower
• Warmer- 50m higher

Question 7

How do glacial/interglacial cycles affect change in water cycle?

Answer 7

Every 100,000 years the earth alternates between glacial and interglacial periods.

Peak of last ice age = 1/3 of earth covered by glaciers and ice sheets- water locked up as snow and ice, freshwater store increases

Question 8

How do farming practices affect change in water?

Answer 8

• Ploughing breaks up soil surface, increasing infiltration
• Crops increase evapotranspiration, reducing chance of soil saturation increasing infiltration.
• Livestock compact soil, decreasing soil stores and infiltration rates
• Irrigation increases runoff levels due to soil saturation
• Soil drainage is common in areas with high precipitation. Using pipes, saturated soils are drained to improve growing conditions and almost double productivity.

Question 9

Example of land use change affecting change in water

Answer 9

• 10% of Amazon Rainforest has permanently disappeared over last 50 years

Question 10

How does land use change affect changes in water?

Answer 10

• Deforestation mainly due to cattle ranching, sugar cane farming and ethanol production -> reduces interception storage, saturing soils quicker and increasing runoff -> long term = water leaves area via local rivers and water cycle becomes permanently disrupted-> results in significantly less rainfall and formation of drought like conditions leading to badlands
• Construction of new buildings and roads creates impermeable surfaces, preventing infiltration. Increases runoff, increasing flood risk

Question 11

Evidence of water abstraction affecting change in water

Answer 11

• London- water abstracted from chalk basin for last 200 years -> over abstraction by water intensive industries left levels 88m below sea level in 1960s -> switch to service industries in 1970s and 80s saw levels rise 3m per year -> population growth in 2000s = levels fall up to 12m, posing a potential threat of saline intrusion again

Question 12

How does water abstraction affect change in water?

Answer 12

• Areas of high population density = high levels of water abstraction
• Reduces water levels in lakes, rivers, reservoirs and groundwater. During dry seasons, more water is abstracted from stores.