The water cycle

Question 1

What is the drainage basin?

Answer 1

An area of land which is drained by a river and its tributaries.

Question 2

What is the drainage basin system?

Answer 2

The movement of water within the drainage basin.

Question 3

Is the drainage basin an open or closed system?

Answer 3

Open, inputs (precipitation), outputs (runoff, evapotranspiration)

Question 4

Describe groundwater flow and its role in the drainage basin system

Answer 4

Feeds rivers through their banks and beds.

Slow transfer, therefore, keeps the river running during dry periods.

Question 5

Describe the role of precipitation and how it is transferred in the drainage basin

Answer 5

Input to the system.
Infiltrates through vegetation.
When it reaches the ground it’s stored as overland flow (puddles), or is infiltrated into the soil.

Question 6

What effects the rate of infiltration?

Answer 6

Saturated soils have a lower infiltration capacity.

Trees encourage infiltration at the roots.

Question 7

What is overland flow and where is it common?

Answer 7

When water is unable to infiltrate through the soil it runs over the surface.
Common in urban areas due to impermeable surfaces,

Question 8

Describe how different soils affect throughflow.

Answer 8

Sandy soils - absorb and transfer
Clay - slow drainage rate
If bedrock is impermeable there is no more downward movement.

Question 9

What causes variations in runoff?

Answer 9

Soil saturation, rock type, vegetation cover
Intensity of precipitation.
Time of year; effects rates of evapotranspiration and vegetation growth

Question 10

Give some examples of the stores in the water cycle

Answer 10

vegetation, interception, groundwater, surface water, soil

Question 11

Give some examples of flows in the water cycle

Answer 11

overland flow, infiltration, stem flow, channel flow

Question 12

Where is most of the earths water stored?

Answer 12

Oceans, in the hydrosphere

Question 13

Explain evaporation and condensation

Answer 13

Evaporation - liquid to gas

Condensation - gas to liquid

Question 14

What is the equation for the water balance?

Answer 14

Precipitation = total runoff + evaporation +/- storage

Question 15

Name some characteristics of the water cycle seen in the rainforest

Answer 15

• High levels of precipitation due to high humidity
• 75% of rainfall intercepted
• 25% evaporated
• Of the remaining 75% ;
  50% used by plants/evapotranspiration
  50% infiltrated

Question 16

Name some impacts of human activity on the water cycle in the rainforest

Answer 16

• Atmosphere less humid, less evapotranspiration
• Soil is compacted by direct rainfall, increases runoff
• Soil is exposed to sun, vulnerable to erosion
• Less interception, less evapotranspiration off leaves

Question 17

Explain how natural variations affect changes in the water cycle

Answer 17

Extreme weather conditions (severe storms or periods of dorughts)

Question 18

Name some human activities which affect change in the water cycle

Answer 18

• Land use changes
• Farming practices
• Water abstraction

Question 19

Explain how change in land use affects the water cycle

Answer 19

• Urbanisation: replaces vegetation with impermeable surfaces, reducing infiltration and increasing runoff. Soil storage and groundwater stores reduced
• Deforestation: removal of trees leading to surface runoff and soil erosion (less interception and infiltration)

Question 20

Explain how farming practices affect the water cycle

Answer 20

Soils covered with vegetation have higher infiltration rates and can hold more water
Desertification reduces soil storage capacity

Question 21

Explain how water abstraction affects the water cycle

Answer 21

Abstraction of water from rivers or aquifers
Aquifers can become depleted and contaminated by inflowing saltwater
Irrigation and land drainage

Question 22

Name some processes which change the magnitude of the water cycle stores

Answer 22

• Precipitation
• Evaporation
• Condensation
• Infiltration
• Interception

Question 23

Name some processes of change at a local level

Answer 23

• Deforestation
• Urbanisation
• Farming
• Storms
• Seasonal changes

Question 24

What is water surplus and what does it cause

Answer 24

Precipitation exceeds evapotranspiration
River levels rise
More runoff and discharge

Question 25

What is water deficit and what does it cause

Answer 25

Evapotranspiration exceeds precipitation

Groundwater depletion

Question 26

How to cryospheric process change the magnitude of water stores

Answer 26

• Snow falling on glaciers is compacted and enters long term storage, forming glacier layers
• Climate change has disturbed the melting and freezing equilibrium, pushes it out of balance

Question 27

Name the main stores of the water cycle:

Answer 27

Lithosphere
Hydrosphere
Cryosphere
Atmosphere

Question 28

Give the percentages for water stores globally:

Answer 28

97. 5% saline water, stored in oceans

2. 5% freshwater, stored as snow and ice (70%) and groundwater (30%)

Question 29

Describe how clouds are formed:

Answer 29

At the equator - High temperatures cause high rates of evaporation, the warm air rises, cools and condense to form clouds and heavy rainfall
In the mid latitudes - Warm air from the Tropics meets cool air from the Arctic, causing air to rise and form into clouds
Strong winds drive these weather systems across the mid latitudes

Question 30

What is the flood hydrograph + describe its features?

Answer 30

A graph showing the discharge of a river following a particular storm event
Peak discharge, peak rainfall, lag time (time between peak discharge and peak rainfall)

Question 31

What does a steep hydrograph show?

Answer 31

Steep slopes
Small basin size
Land is mainly urbanised
Soils are saturated

Question 32

What does a shallow hydrograph show?

Answer 32

Permeable rocks
Forest type land - increases interception
Dry soil
Gentle slopes