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Water footprint calculations. Four countries (A, B, C, D) planing to trade rice.

ID: 803556 • Letter: W

Question

Water footprint calculations.

Four countries (A, B, C, D) planing to trade rice. All four countries produce rice and virtual water content per ton of the product rice is estimated to be:

Country A=1275 m3/ton
Country B=2182 m3/ton
Country C=5455 m3/ton
Country D= 3103 m3/ton

After negotiations, they agreed that the product trade between countries A and B is 488.100 ton/yr and between countries C and D 416.300 ton/yr.

1) calculations of annual national water footprint for the rice (for all countries). You should be able to label these values as a national water loss or national water saving.

2) calculate globally water saving (loss) for this product.

3) analyze these results and inform the water committee if these two trades are water sustainable. What are your recommendations for future trades?

Explanation / Answer

1.Water footprint is the ratio of total volume of water used to the yield of the crop

For country A virtual water content=1275m3/ton

Trade between A and B=488.100 ton/year and country A sells rice to country B

Annual national water loss for country A=virtual water content* amount of crop exported

=1275*488.100=622,327.5m3/year

For country B virtual water content=2182m3

If country B imports 488.100 ton /year from country A

Annual national water saving B=virtual water content * amount of crop imported

=2182*488.100

=1065034.2m3/year

For country C virtual water content=5455m3/ton

If country C sells 416.300 ton/year rice to the country D then

Annual national water loss=5455*416.300=2270916.5 m3/year

For country D virtual water content=3103m3/ton

If country D imports 416.300 ton/year rice from country C then

Annual national water saving=3103*416.300=1291778.9m3/year

2. Global water saving= Product trade between countries*( virtual water content of country A- virtual water content of country B)

=488.100ton/year*(2182-1275 m3/ton)

=488.100*(907)

=442706.7m3/year

positive sign indicates that it is a global water saving if country A export rice to country B.

Global water saving between C and D=416.300*(3103-5455)

=416.300*-2352

=-979,553.9

negative sign indicates that it is losing if country C export rice to country D

3. The trade between the countries A and B is sustainable whereas the trade between the countries C and D is not feasible since the crop requires lot of water to grow. So it is recommended that the quantity of export or import should be limited between country C and D.