2006 World Water Forum
The fourth annual World Water Forum starts today in Mexico City. Here are the relevant World Bank links. Or take this BBC quiz to see how much you know about water.
Update: Ironically, the overexploitation of subterranean water reserves is making Mexico City sink - faster than Venice. More warnings and criticisms via The Guardian, ABC, and NYTimes.
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The world water leaders currently meeting need to inform themsleves about aquaponics if they are to seriously understand how to cope with water scarcity and food security.
Aquaponics appears to be the world’s most productive food system in terms of water use efficiency. That can be expected to be a political ace for aquaponics science technology and practice as the world’s fresh water supplies come under increasing pressure – especially in urban areas.
Depending on where it is practiced, much aquaponics takes only about half the volume of water to produce $100 worth of food in the form of fresh fish and fresh vegetables or fruit – whatever the currency – than inorganic hydroponics. The accompanying table uses Australian figuring. It shows just how badly other food production systems perform. Inorganic hydroponics is the only close contender for the title of “Most Miserly Water User”.
TABLE: COMPARISONS OF WATER USE FOR FOOD PRODUCTION
Litres of water per A$100 of output:
Rice 470,000
Cotton 160,000
Milk 147,000
Sugar 123,900
Beef cattle 81,200
Vegetables and fruit (soil grown) 37,900
Wheat 24,500
Hydroponic crops 600
The Aquaponics Network Australia, estimates water use for Australian aquaponics in the tropics and sub-tropics as being:
Aquaponics -- fish and lettuce 500
Aquaponics --fish and basil 173
In Melbourne’s temperate climate evapo-transpiration water loss in aquaponics has been cut to around 0.15% water top-up a day. This means that in an aquaponics “farm” in Melbourne the top up of water each year is about 55% of the total water volume in the system. For every tonne of fish produced each year, the fish wastes can produce from five to seven tonnes of salad vegetables or herbs. About one tonne of fish and from five to seven tonnes of vegetables or herbs can be grown for every 22 cubic metres (22,000 litres) of water, with the plant crop renovating the water for the fish crop. The United States and Canada have been the global leaders in aquaponics development since the 1980s. But Australia is fast developing as a significant aquaponics leader also – especially in “extensive aquaponics” that is also named “integrated agri-aquaculture”. One intensive aquaponics project now starting in Australia expects to reduce the water use to 15 to 20 litres per $100 of farm gate produce.
NOTE: The first section of figures in the table above were reported at the International Conference and Exhibition on Soilless Culture in Singapore in September 2005 by Graeme Smith,President - Australian Hydroponic & Greenhouse Association. He said he obtained the figures from Dr Derek Eamus (University of Sydney) who was keynote speaker at the AHGA conference in Melbourne in 2003. Mr Smith said the figures were checked with Australian Government sources. The 600 litres per $100 of produce figures he quoted for hydroponics was based on lettuce in a simple NFT system. No figures are available for other hydroponic crops. Mr. Smith believes they would not be much different.
Geoff Wilson,
Convenor.
Aquaponics Network Australia and President, Urban Agriculture Network-Western Pacific.
Posted by: Geoff Wilson | Mar 19, 2006 9:02:17 PM