hydrosphere

Question 1

Explain how human activities can impact on the hydrological cycle (10)

Answer 1

Deforestation - will result in more surface runoff, cause more extreme river flows - more water entering the river channel

Urbanisation - increases surface runoff , infiltration is reduced, and river levels will rise due to surface runoff

Irrigation - reduce river flow

Afforestation increases interception and transpiration rates in the drainage basin - reduce surface runoff

Building dams and reservoirs stops peaks and lows of the river system and evens out river discharge which increases the amount of water available for evaporation

Straightening river channels - the speed of channel flow

Mining reduces vegetation cover and increases runoff, higher evapotranspiration changed rainfall patterns

Question 2

Discuss the movement of water within a drainage basin (8 marks)

Answer 2

Water in stores, such as oceans and lakes will be warmed by the sun, evaporated

The water, now a gas, will travel up in the atmosphere where it will cool and condense to form clouds

Clouds will build until they get too heavy, precipitation

Some of the rain/sleet/snow may be prevented from reaching the ground due to vegetation like trees which is called interception

This can be transpirated which is when the water is directly evaporated from the plants

The other water that reached the soil can be evaporated which is when water is warmed by the sun and turns from liquid to gas in the atmosphere

The water that isn’t intercepted or revaporated will be infiltrated meaning that it moves down into the soil

This water moves from the soil into the rocks below through the pores, this is percolation

This water is then stored as ground water and flows underground through rocks which is called groundwater flow