Human Factors Affecting the Hydrological Cycle

Question 1

all factors (6)

Answer 1

• deforestation
• irrigation
• urbanisation
• mining
• dam building and reservoirs
• afforestation

Question 2

deforestation

Answer 2

• decreases interception, so precipitation will hit the soil more directly, increasing runoff and soil erosion
• decreases evapotranspiration , so less clouds form, leading to less rainfall
• river flow more extreme as there are less trees to store water

Question 3

irrigation

Answer 3

• taking water from underground aquifers causes decreased river flow and lower water tables
• more water stored on the surface means more evapotranspiration
• irrigation washes out salts from from below the level of plant roots, but as the soil dries, capillary action brings the salts to the surface, killing plants

Question 4

urbanisation

Answer 4

• impermeable surfaces like concrete reduce infiltration, and increase overland flow, leading to increased river flow and risk of flooding
• reduces the water table by reducing the amount of water returning to groundwater storage

Question 5

mining

Answer 5

• reduces vegetation cover, causing decreased interception and therefore increased runoff, more evaporation and therefore an altered rainfall pattern
• causes silting up of lakes/reservoirs leading to reduced storage capacity

Question 6

dam building and reservoirs

Answer 6

• increases evaporation due to increased water surface area
• increases the water table

Question 7

afforestation

Answer 7

• increases interception and evapotranspiration , increasing cloud formation and rainfall
• more water will be stored in trees, so there will be less runoff and river flow