Unit 8: Our Water Footprints
Calculating water footprints activity guide, handout and worksheet
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This project was funded by the Department of Sustainability and Environment.
This work is licensed under Creative Commons Attribution 2.5 Australia licence. A copy of this licence is available at http://creativecommons.org/licenses/by‐nc/2.5/au/ or by writing to info@creativecommons.org.au. However logos are protected by copyright. Page 1 of 8
Unit 8: Our Water Footprints
Calculating water footprints activity guide, handout and worksheet
Estimated duration: 50 minutes
Aim • •
To develop an understanding of the embodied water in different agricultural products To develop an awareness of the water footprint connected with our food consumption patterns
Outcome By the end of this class, students will be able to: • better analyse graphical and numerical information • display improved skills in translating everyday numerical concepts to interpret public information
Resources • • • •
Worksheet: Calculating water footprints (included below) Computers with internet access OR the handout: ‘Calculating water footprints’ (included below) Water footprint calculator at www.waterfootprint.org1 Cards from the embodied water game (part of the embodied water activity, earlier in this unit)
Activity Description 1. Provide students with copies of the worksheet (included below). 2. Introduce students to the idea of a water footprint calculator as a way of quantifying how much embodied water we consume based on a person’s country, gender, income and food intake. 3. If computers and internet access are available, direct students to the website www.waterfootprint.org. (If computers are not available, work from the handout and the worksheet. Use the handout to analyse some sample results.) 4. If using the website, follow the link “Your Footprint Calculator” on the left. The Quick Calculator will ask students for their country, gender, whether they are vegetarian and how much meat they consume. It will then ask them their gross yearly income (note: income in US dollars). According to the Australian Bureau of Statistics the average Victorian income (per person) 2003/04 was AUD $38,754 (see ABS publication no. 5673.0.55.001). The water footprint calculators are under copyright: © 2005 Arjen Y. Hoekstra, Ashok K. Chapagain and Mesfin M. Mekonnen
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5. Students can record the results of their own water footprint (or of the sample footprint in the handout) on the worksheet and answer the questions. If students are interested you can help provided some estimates for income. They need to divide their parents combined income by the number of people in the household. (See note below) For example, two full time teachers with two children might earn $150,000 per year divided by 4. Each person would earn $37,500 each year gross (before tax). If they have a parent who is a tradesperson or builder (e.g. electrician) that person may earn $150,000 alone. Note: It is important to treat information about income sensitively as it is usually private and confidential information. Students may have parent(s) who are currently unemployed or be low income earners so try not to give this too much emphasis in the class. Alternatively, they could use figures based on their own future career plans. Extension Activity Students can obtain a more detailed estimate of their water footprint by using the extended online calculator, obtaining information about specific quantities of food they eat. Interviewing the family shopper or a food technology expert will help them obtain a more accurate read‐out of their footprint. Additional teacher information: What is a water footprint? Like an ecological footprint, a water footprint “calculates the number of earths that would be needed to sustain our population if everyone in the world had the same lifestyle as people in the West.” From www.savewater.com.au/index.php?sectionid=43 Some facts and figures: • • •
The water footprint of China is about 700 cubic metres per year per person. Only about 7% of the Chinese water footprint falls outside China. Japan, with a footprint of 1150 cubic metres per year per person, has about 65% of its total water footprint outside the borders of the country. The USA’s water footprint is 2500 cubic metres per year per person.
Student Roles and Responsibilities Participate in agreed tasks Contribute to class discussions Complete activities and worksheets Work cooperatively with others Seek teacher assistance and support when needed
Level of Teacher Support Facilitate discussion Page 3 of 8
Organise materials and equipment Provide encouragement Introduce tasks and activities Provide assistance when requested Teach or reinforce statistical or graphical skills and understanding
Assessment To use this learning activity as an assessment task, collect evidence such as: Teacher checklist and observation Copies of student materials and worksheets Teacher checklist for class discussions
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Unit 8: Our Water Footprints
Calculating water footprints worksheet
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Sort through the cards from the “Embodied Water Card Game”. Divide the cards into categories of “Essential things”, “Things I can cut down on” and “Things I can really do without”. Compare your results with other people in the class. People with vary because they have different values and preferences about what gives them pleasure. Complete your water footprint calculation using the water footprint calculator at www.waterfootprint.org . Alternatively, look at the student handout “Calculating water footprints handout” and look at the results obtained by Mike the Mighty Meat‐eater. Answer the following questions in regard to your water footprint graphs or Mike’s. a. What is the total volume of water you consume each year in cubic metres? b. If an Olympic swimming pool contains 2500 cubic metres of water, estimate what proportion of a swimming pool you consume each year. c. What volume of your total water footprint is due to food? _______ d. What volume of your total water footprint is due to domestic use? ______. Give some examples of domestic water use. e. What do you notice when you compare water consumed for domestic use and that used for food?
Calculating Percentages for Nifty Comparisons Using percentages is a really useful way to compare numbers because you are comparing numbers relative to 100 which is a nice round number. Try converting the each category of your water footprint to a percentage of the total. For example, if your total is 900m3 (900 cubic metres) you can compare
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each other number to that by dividing and then multiplying by 100. If your food requires 700m3, then that is 700/900 X 100 = 78% of your footprint. On the other hand, if your domestic use accounts for 160m3 then that is 160/900 X 100 = 18% Calculate your own water footprint percentage for food and domestic use. You can see that the embodied water in the food you eat accounts for more than FOUR times the water you use for domestic purposes. Of course, we HAVE to eat, even more than having a shower every day and having clean clothes. Perhaps there might be smarter foods to eat, given that we are running out of fresh water. What do you think? Now, look at the second table on the handout or on the online calculator. Notice that it specifies which types of foods contribute the most to the water footprint. Answer the following questions based on the results on the graph. Q. What two kinds of food make the biggest contributions to the water footprint? Q. How many cubic metres do they contribute to your footprint? Q. Convert these figures into percentages of your food water footprint. Q. What kinds of food contribute the least? Q. Make some suggestions about how the average Australian can reduce their water footprint by eating differently. Q. Would there be any other benefits to changing their diet in this way? Q. What would be the costs to a) individuals? b) to some farmers? Page 6 of 8
Unit 8: Our Water Footprints
Calculating water footprints handout Mike the Mighty Meat‐eater completed the Quick Calculation of his water footprint at www.waterfootprint.org and obtained a read‐out to show how his water consumption compared to the global average. The numbers in his read‐out correspond to volume in cubic metres. (An Olympic swimming pool typically contains 2,500 cubic metres of water by comparison.) Components of Mike’s water footprint per year and comparison to the global average
1243
3572
Average global Mike’s footprint footprint
2546 Bit of his footprint from food
523 Bit of his footprint from industry
504 Bit of his footprint from water use at home
In this case, Mike’s consumption of 3572 cubic metres per year is a lot more than the global average. Notice that the largest category in his total is 2546 cubic metres and that it is due to the food he eats. A relatively smaller amount of 504 cubic metres is due to his domestic use (shower, washing machine, drinking and cooking).
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Contribution of individual food categories to Mike’s total water footprint
202 Cereal
1538 Meat
25 105 Vegetable Fruit
357 Dairy
318 Others*
*’Others’ include vegetable oil, starchy roots (cassave, potato), sugar & sweeteners, pulses, animal fats, nuts, stimulants (coffee, tea, cocoa).
This graph show’s how much of Mike’s water footprint is due to the different types of foods he is likely to eat. What kinds of foods contribute the most to his footprint? This quick calculation is an estimate based on the average Australian male. However, if you would like to assess your water footprint based on your specific consumption pattern you can complete to the Extended Version of the individual water footprint calculator, at www.waterfootprint.org . In this case you might have to talk to the person who does your weekly shopping as you need to know how many kilograms of different foods you consume.
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