Explain how human activities can impact on the hydrological cycle (12)

Question 1

Deforestation

Answer 1

• TRI less evapotraspiration so there is less cloud formation
  and less precipitation elsewhere.
• Increasing river levels can lead to flooding and more
  erosion TIB the rivers are faster & more powerful.

Question 2

Dam Building

Answer 2

• Increased infiltration TMT the water table around the
  dam site is also increased. However there is a decrease
  in river flow downstream of dam there is a lowering of the
  water table in this area.
• Flood control TMT dams can reduce the fluctuations in a
  rivers discharge downstream TMT less water will reach
  the sea. eg)

Question 3

Reservoirs

Answer 3

• There will be an increase in evaporation from surface
  storage TMT it will lead to an increase in cloud formation
  and precipitation.
• Increased infiltration and percolation TMT there will be
  an increase in ground water.

Question 4

Mining

Answer 4

• Removes vegetation so soil will be loose TMT there is an increase in surface runoff TMT silt is washed into rivers.
• Whole reservoirs can be filled in with this eg) Mayem Lake, Goa, India - is totally silted up

Question 5

Irrigation

Answer 5

• If water is drawn from underground, TMT there is increased evaporation, reduced groundwater storage and increased surface storage (rivers & lakes) TMT it results in the lowering of the water table TARI salinisation of the soil due to minerals in the water surface resulting in a crust forming.

Question 6

Urbanisation

Answer 6

There is a high drainage density, associated with the network of drains, gutters, sewers and flood relief channels. TMT it increases surface runoff into river channels, also increasing channel storage. TMT this can lead to flooding downstream.