1. Area of study 3: Physical Systems and Sustainability
Topic 5: The Water Cycle and Water Insecurity
EQ1: What are the processes operating within the hydrological cycle from global to local scale
EQ2: what factors influence the hydrological system over short- and long-term timescales?
EQ3: How does water insecurity occur and why is it becoming such a global issue for the 21st century?

2. Specification content
2 HOURS
1 DOUBLE
1 HOUR
½ DOUBLE

3. Today we are learning this content:
5.1 (a, b and c)

4. Topic 5: The Water Cycle and Water Insecurity
Aim: You must understand that this a physical geography unit. Key terms are highly important. You must know ALL terms within this unit. This unit is approx. 18 lessons. There will be assessments along the way!

5. Enquiry question 1: What are the processes operating within the hydrological cycle from global to local scale?
Present new information
Overview
Water plays a key role in supporting life on earth. The water cycle operates at a variety of spatial scales and also at short- and long-term timescales, from global to local. Physical processes control the circulation of water between the stores on land, in the oceans, in the cryosphere(is the frozen water part of the Earth system- frozen parts of the ocean, such as waters surrounding Antarctica and the Arctic), and the atmosphere. Changes to the most important stores of water are a result of both physical and human processes.
Water insecurity is becoming a global issue with serious consequences and there is a range of different approaches to managing water supply.

6. 1. The Hydrological Cycle at a ‘Global Scale’
Present new information
1. The Hydrological Cycle at a ‘Global Scale’
Aims: To understand the hydrological cycle, annual fluxes and the global water budget.
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7. The hydrological cycle
Earth's water is always in movement, and the natural water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth. Water is always changing states between liquid, vapor, and ice, with these processes happening in the blink of an eye and over millions of years.
Global water distribution
For an estimated explanation of where Earth's water exists, look at the chart on the next slide. By now, you know that the water cycle describes the movement of Earth's water, so realize that the chart and table below represent the presence of Earth's water at a single point in time. If you check back in a thousand or million years, no doubt these numbers will be different!
Notice how of the world's total water supply of about million cubic miles of water, over 96 percent is saline. And, of the total freshwater, over 68 percent is locked up in ice and glaciers. Another 30 percent of freshwater is in the ground. Fresh surface-water sources, such as rivers and lakes, only constitute about 22,300 cubic miles (93,100 cubic kilometers), which is about 1/150th of one percent of total water. Yet, rivers and lakes are the sources of most of the water people use everyday.

8. Are you drinking the same water as we use to?

9. Starter – 5 mins
1. Where does our water come from? In pairs or small groups, students to try to come up with different ideas as to where our water comes from originally.
2. Draw the water cycle and add as many labels as you can!
The Hydrological Cycle:

10. The Hydrological Cycle
NASA:

11. Water

12. The water cycle and water insecurity
Prepare for learning
Complete the key terms grid
Green water
Stores
Fluxes
Processes
Blue flows
Cryosphere

13. The water cycle and water insecurity
Prepare for learning
Answers
Green water
Stores
Fluxes
Processes
Blue flows
Cryosphere
Blue flows
Green water
Fluxes
Cryosphere
Stores
Processes

14. The Hydrological Cycle on a global scale
Present new information
The easiest way to understand the Hydrological Cycle is to view it as a system which has key components. These are key to understanding how movement within the system occurs:
STORES: these are stocks of water, places where the water is held. For example, the oceans.
FLUXES: this is the measurement of the rate of flow between the stores.
PROCESSES: the physical factors which drive the fluxes of water between stores.

15. The Hydrological Cycle
Present new information
The hydrological cycle is a closed system because all the water is continually circulated through the stores and there is a constant amount of water in the system. The system does not change because there are no gains or losses to other systems.
What does solar energy have to do with the water cycle?
Heated by the sun, the water on the earth’s surface evaporates into the atmosphere, while water is also drawn from the soil by plants and evaporated from leaves and stems by the process of evapotranspiration.
What does gravitational potential energy have to do with the water cycle?
This energy is converted into kinetic energy as the water moves through the system by plant interception or over land as surface runoff. Water also flows through the soil by the processes of infiltration and throughflow

16. The Hydrological Cycle facts
Present new information
The water is held in different states (liquid, gas and solid) and stores which vary for
both human and physical reasons.
In the last Ice Age more water was held within the cryosphere in a solid form as snow and ice.
Fixed amount of water on the planet that is constantly recycled
NO EXTERNAL INPUTS OR OUTPUTS – this is crucial for your understanding
There are inputs and outputs WITHIN THE SYSTEM itself.
The water exists in various forms
Solid – ICE
Liquid – WATER
Gas – VAPOUR
For example in the last Ice Age more water was held in solid form
Recent years has seen more liquid water in the system
Water is held in STORES
Oceans
Cryosphere - Ice
Land – rivers, streams and lakes
Vapour in atmosphere – in clouds
There are FLOWS which are driven by processes such as precipitation and evaporation. High flows as per diagram on page 3 can be seen e.g evaporation.
Recent climate warming is reversing this with major losses of ice in Greenland and Antarctica.
Humans have built water storage reservoirs (on a smaller scale) which has increased the security of their water supply.

17. Present new information

18. The Global Hydrological Cycle
Construct new meaning
On your sheet, look at 1, 2, 3 and 4. Decide which of the statements in the boxes below correspond to the numbers on the diagram. Write them onto your sheet and add these notes too! 2 3
On the land water is stored in rivers, streams, lakes and groundwater in liquid form. It is often known as blue water; it is the visible part of the cycle.
Water is also stored in vegetation or in the soil. This is known as green water; the invisible part of the cycle.
In the cryosphere water is largely found in a solid state, with some liquid form as melt water and lakes. 4
Water largely exists as vapour in the atmosphere with the carrying capacity directly linked to the temperature. Clouds can contain liquid water or ice crystals (only at high altitudes). 1
In the oceans the vast majority of water is stored in liquid form, with only a minute fraction as icebergs.

19. Stores, flows/fluxes and processes4 2 3 1

20. Major Fluxes
Present new information
The major fluxes are shown by the numbers, driven by key processes such as precipitation, evaporation.
These fluxes have been quantified – the most important being evaporation from the oceans.

21. Water Stores Construct new meaning
Within the booklet in pairs write in the name of the store where you think it belongs once you have looked at the data. Don’t cheat and look at the textbook.
Store
Volume (10(3) KM(3)
% of total water
Percentage of fresh water
Residence time
1,335,040
96.9
3,600 years
26,350
1.9
68.7
15,000 years depending on size
15,300
1.1
30.1
Up to 10,000 years for deep groundwater; years for shallow
178
0.01
1.2
2 weeks to 10 years; 50 years for very large scale
122
0.05
2-50 weeks 13
0.001
0.04
10 days
Rivers and lakes
Atmospheric moisture
Ground water
Oceans
Soil moisture
Ice caps

22. Main global water stores
Construct new meaning
Which is the world’s largest water store and what percentage of the world’s water is contained in it?
The atmosphere is the smallest store of water, why might this be?
Look at the residence time column. What does that tell you about the different stores of water?

23. Answers
Construct new meaning
Which is the world’s largest water store and what percentage of the world’s water is contained in it? Oceans -96.9%
The atmosphere is the smallest store of water, why might this be? It soon evaporates, condenses and falls to Earth as precipitation.
Look at the residence time column. What does that tell you about the different stores of water? The largest stores have the longest residence time/longest time spent in that store.

24. Residence Times
Present new information
The table shows residence times. These are the average times a water molecule with spend in the reservoir or store. Residence times impact on turnover within the water cycle system. Some ancient groundwater, such as that found deep below the Sahara Desert – the result of former pluvial (wetter) periods – is termed fossil water and is not renewable or reachable for human use.
Major ice sheets store water as ice for very long periods, so the data shows an average.
Ice core dating has suggested that the residence time of some water in Antarctic ice in over 800,000 years.

25. Residence Times
Present new information
Conversely, some very accessible stores, such as soil moisture, and small lakes and rivers, have much shorter residence times.
Water stored in the soil, for example, remains there very briefly as it spread very thinly across the Earth. Because of its accessibility it is easily lost of other stores by evaporation, transportation, groundwater flow or recharge.
Atmospheric water has the shortest residence time (around 10 days); as it soon evaporates, condenses and falls to the Earth as rain.
There is a strong link between residence times and levels of water pollution: stores with a slower turnover tend to be more easily polluted as the water is in situ for a longer length of time.

26. In both the Sahara and Antarctica, examples you will be looking at, it shows water stored for a long period of time. Additionally these stores of water are not very accessible.
However there are more accessible stores such as soil, lakes and rivers – These all have a lot shorter residence times
For example water stored in the soil remains there briefly as it spread very thinly across the Earth. Due to its accessibility it is easily lost to other stores such as transpiration and groundwater

27. Fossil Water
Present new information
This is water that is found very deep and out of reach from humans and is not renewable
Examples:
Ancient water under Sahara Desert which stored there after wet periods in that area 5000 years ago when there were active river systems
Major ice sheets such as Greenland and Antarctica store water as ice for very long periods of time.
Ice core dating from Antarctica has suggested residence time of 800,000yrs!

28. Present new information
Atmosphere
60,000
90,000
370,000
400,000
Ocean
Land
30,000

29. Annual Fluxes Present new information
Major fluxes are driven by key processes such as precipitation, evaporation, cryospheric exchange and a runoff generation.
Construct new meaning
The following important points emerge from this Table:
(1) More water is evaporated from the oceans than falls on to them as precipitation, and more water falls as precipitation on to the land masses than is evaporated. The balance is made up by river runoff. If the precipitation and evaporation budget did not work in this way, the land masses would progressively dry up, and oceans would progressively gain all of the world's water.
(2) The annual flux of water through the atmosphere is about 460,000 cubic kilometres per year, about 35 times larger than the amount held in the atmosphere at any one time. This means that the average residence time of water in the atmosphere is very short. In contrast, the size of the ocean reservoir is over 3,000 times larger than the annual flux to the atmosphere or from the atmosphere and land masses, so the average residence time of water in the oceans is very long.

30. Answers
Construct new meaning
Ocean-atmosphere flux - More water is evaporated from the oceans than falls on to them as precipitation
Atmosphere-land flux - More water falls as precipitation on to the land masses than is evaporated
Land – Ocean Flux - The balance (30) is made up by river runoff(arrow going from land to ocean). If the precipitation and evaporation budget did not work in this way, the land masses would progressively dry up, and oceans would progressively gain all of the world's water. Less evaporation from the land as stores in soil, blue water and groundwater.

32. Annual Fluxes Apply to demonstrate
Make sure you use data.
The following important points emerge from this Table:
(1) More water is evaporated from the oceans than falls on to them as precipitation, and more water falls as precipitation on to the land masses than is evaporated. The balance is made up by river runoff. If the precipitation and evaporation budget did not work in this way, the land masses would progressively dry up, and oceans would progressively gain all of the world's water.
(2) The annual flux of water through the atmosphere is about 460,000 cubic kilometres per year, about 35 times larger than the amount held in the atmosphere at any one time. This means that the average residence time of water in the atmosphere is very short. In contrast, the size of the ocean reservoir is over 3,000 times larger than the annual flux to the atmosphere or from the atmosphere and land masses, so the average residence time of water in the oceans is very long.
Using the notes you have made along with the data and diagram analyse the relative importance of the annual fluxes.

33. The following points emerge from this table..
Review
(1) More water is evaporated from the oceans than falls on to them as precipitation, and more water falls as precipitation on to the land masses than is evaporated. The balance is made up by river runoff. If the precipitation and evaporation budget did not work in this way, the land masses would progressively dry up, and oceans would progressively gain all of the world's water.
(2) The annual flux of water through the atmosphere is about 460,000 cubic kilometres per year(400 ocean + 60 land). The average residence time of water in the atmosphere is very short 10 days. In contrast, the size of the ocean reservoir (1335 km3) is much larger than the annual flux to the atmosphere(460km3) or from the atmosphere(460km3) and land masses(60km3), so the average residence time of water in the oceans is very long.

34. Where is Earth's water? For a detailed explanation of where Earth's water is, look at the data table. Notice how of the world's total water supply of about 333 million cubic miles (1,386 million cubic kilometers) of water, over 96 percent is saline. And, of the total freshwater, over 68 percent is locked up in ice and glaciers. Another 30 percent of freshwater is in the ground. Thus, rivers and lakes that supply surface water for human uses only constitute about 22,300 cubic miles (93,100 cubic kilometers), which is about percent of total water, yet rivers are the source of most of the water people use.

35. Lakes (natural and artificial) – 52%
Present new information
Apply to demonstrate
Lakes (natural and artificial) – 52%
Soil moisture – 38%
Atmosphere – 8%
Rivers – 1%
Living things – 1%
Notes: This is fresh water supply. About 69% is locked up in snowflakes, ice sheets and ice caps/glaciers. This is largely inaccessible for human use but mountain streams as snow melt from these areas are used for drinking water. Another 30% is groundwater which is very deep seated known as fossil water and cannot be accessed. That leaves only 1% of fresh water is easily accessed for human use. Technology is very important and figure 1.2 d shows current levels with current technology. Rivers are a main source of surface water % . Its not surprising that there are so many concerns regards the usage of this tiny amount available. Its an unequal world in terms of access – technology, climate, wealth, government power…… Technology is being used to extend the availability e.g desalination plants.
Use the following data to construct a fourth data column for ‘Accessible Surface Freshwater’ (see page 4 Hodder if you get stuck)
Describe the distribution of water in the figure you have just drawn.

36. Important points from the data..
Review
This is fresh water supply. About 69% is locked up in snowflakes, ice sheets and ice caps/glaciers. This is largely inaccessible for human use but mountain streams as snow melt from these areas are used for drinking water. Another 30% is groundwater which is very deep seated known as fossil water and cannot be accessed. That leaves only 1% of fresh water is easily accessed for human use. Technology is very important and figure 1.2 d shows current levels with current technology. Rivers are a main source of surface water % . Its not surprising that there are so many concerns regards the usage of this tiny amount available. Its an unequal world in terms of access – technology, climate, wealth, government power…… Technology is being used to extend the availability e.g desalination plants.

37. Where is the Earth’s Water?
Present new information
Read through the information and highlight the key terms or data.
Construct new meaning

38. Human Life Support
How accessible is water for human life support? (P4&5 Hodder)

39. 1. Explain the difference between blue and green water (3)
2. Explain why a large proportion of the world’s freshwater is unavailable for human use (4)
3. Explain why the global hydrological cycle is an example of a closed system (4 marks)
(Define the term closed system and use named processes and stores to show why the water cycle is closed)
Examples of exam style
questions!

40. Important Key Terms – Complete the Heads and Tails!

41. Read and highlight the article on fossil water in the Sahara desert
Apply to demonstrate
fossil-aquifer-beneath-sahara-desert-slowly-refilling.htm
Read and highlight the article on ice sheets in Antarctica
Summarise each article in 3-4 bullet points

42. Review The 3 largest stores according to size are?
OCEANS 96.9%
ICECAPS 1.9%
GROUNDWATER 1.1%
You must learn this cycle
!!!
Remember it’s a system
of flows and stores.
ITS A CLOSED SYSTEM!

43. Review https://water.usgs.gov/edu/watercycle.html

44. LEARN THIS BEFORE NEXT LESSON!!!
Review

45. Homework: Reading Oxford Book pages 8-11
Solar energy, Climate and moisture levels
which link to evaporation and precipitation
Gravitational energy
Global Extremes – Polar vs Tropical
Global Water Budget
The importance of the Tropics

46. Homework: Human life support
See page 4 and 5 and make notes, Hodder
Make sure you understand where Earths water is stored
Which stores are accessible by humans
This is a area of conflict and will continue to be so with climate change!
It’s a very unequal world of access
Technology is hugely important