Real and Virtual Water and Water Footprints: A Comparison between the Lower Fraser Valley and the Okanagan Basin
Hans Schreier from UBC is doing innovative work on the concept of "virtual water", which is the water that is needed to produce food or a commodity. Most staple crops require about 1000 L of water to produce 1 kg of grain. Rice requires two to three times this amount, and meat production takes four to thirty times this amount. In a time when some regions are experiencing water scarcity and with the threat of climate change, we have the opportunity to reorganize how and where food is produced to better reflect the amount of water available. Schreier is currently studying two rapidly growing agro-climatic regions in BC - the Okanagan Basin and the Lower Fraser Valley - to determine how much water is used for food production, how much of this is exported from each basin, and how much virtual water is imported. The Okanagan Basin is one of the driest basins in Canada, yet it is a net exporter of food. With rapid growth in both population and agricultural production, the basin is under pressure because almost all the surface water resources are fully allocated. In contrast, the Lower Fraser Valley is one of the wettest areas in Canada and has the capacity to grow more water intensive foods and increase its exports of virtual water.
Schreier and his colleagues have just completed a new report on this work supported by the Walter and Duncan Gordon Foundation, with some illuminating conclusions.
Analysis of crops in both areas looked at water requirements, water used and the virtual water content. The greatest crop water requirement on a per ha basis in the Lower Fraser valley are for hay and silage fodder (114Mm3/yr) followed by at corn (28 Mm3/yr). In the Okanagan, the greatest crop water requirement is cherries, pears, apples (42 Mm3/yr), peaches and alfalfa (120 Mm3/yr). Alternatively, actual water used on crops is as follows: grain and field crops account for 78% of overall crop water used and berry crops 15% in the Lower Fraser Valley. In the Okanagan area, grain and field crops account for 72% of the crop water used and fruit production accounts for 26%.
In terms of virtual water content alfalfa, hay, fodder, raspberries and blueberries have the highest water contents on a m3/ton basis in the Lower Fraser Valley. Alfalfa, hay, fodder, cherries and peaches have the highest VWC in the Okanagan Basin
The study also compared water use with crop value. The four main berry crops produced in the Lower Fraser Valley (raspberries, blueberries, cranberries and strawberries was $133 million and used 32 Mm3 of water. The four major fruit crops in the Okanagan (grapes, apples, cherries, and peaches) was $81 million using 63 Mm3 of water.
Since approximately 90% of the available water is currently being used how the area is consuming and using water should be reconsidered to accommodate anticipated future growth. Virtual water calculations are a new, innovative and useful tool to examine water use and assist decision makers in strategic land development choices.
See the full report "Real and Virtual Water and Water Footprints: A Comparison between the Lower Fraser Valley and the Okanagan Basin" for more information.