Tuesday, November 3, 2009

'Urban and Rural Irrigation Water in Beijing' by Devon Holdsworth

One of the leading producers and consumers of agricultural products in the world is China. Nearly 300 million Chinese farm workers are in the industry working on virtually all of the arable land in the country. Beijing’s econmy relies greatly on its agriculture, as it is their primary industry. With a population of 13, 000, 000 their urban agriculture is greatly relied upon to be a source of inexpensive food as opposed to the alternative of importing goods. Therefore, it is not a shock to find out that their ground water resources are quickly depleted from farming and in some places the water table has become over 20 m deep making it completely impossible for farmers to tap into. For many years farmers in Beijing have compensated for this by reusing wastewater, however they have not been practicing proper wastewater management until very recently. It was not until 2000 that they started to use water from central wastewater treatment plants. The organization known as SWITCH is now projecting high hopes for the future of Beijing’s water; with the use of water treatment plants the water table is hoped to be restored to 1960s levels, rivers and lakes will meet Surface Water Quality Standards grade III and above and tap water will reach international drinking water standards.

In the 1980s Beijing’s population was discharging 2,000,000 cubic meters of sewage; half from domestic wastewater and half from industries but nearly all of it was pumped into rivers and lakes without receiving any treatment. Beijing is still recovering from their previously low standards of sanitation and the Gaobei Dian Wastewater Treatment Plant is playing a large role in this by treating 40% of Beijing’s daily untreated wastewater. Beijing’s water is treated to the secondary level by neutralizing and disposing the wastes using biological matter, which makes it suitable to be used for agriculture. Now 1,350,000,000 cubic meters of water is discharged, of this 1,000,000,000 cubic meters of water is treated and of this 230,000,000 cubic meters is used for agriculture. Not only is this plant promoting sanitary wastewater concerns, it is also restoring Beijing’s natural habitat, boosting their economy by providing water for the agricultural industry and it is providing job opportunities for the people of Beijing.

1. Gaobei Dian Wastewater Treatment Plant

Unfortunately water from wastewater treatment plants is not available to all farmers in Beijing, some are too far removed in rural areas from these plants to access it. For these farmers there is another option, which is harvesting rainwater. This technique is also used by many citizens in residential areas and has been largely promoted since the year 2000. There are multiple techniques to do this, which makes clean rainwater available to almost anybody. One technique includes water pooling in roadside gutters, storing in local deposit pools, and then being transferred to large water-saving ponds for primary treatment (sedimentation). The most common form of rainwater harvesting which has been practiced for thousands of years in rural China uses the roofs of houses and since recently greenhouses have been promoted for capturing rainwater and irrigating crops.

2. Greenhouse Rainwater Harvesting System

One greenhouse, which is specially made to incorporate rainwater harvesting, can on average collect 200-300 cubic meters of rainwater each year, which can irrigate large amounts of area with efficient (drip) irrigation. Unfortunately at this time only 1 percent of irrigation systems in government subsidized farming uses rainwater as only twenty of these greenhouses now exist, however it is expected that more will be built.

Beijing is now doing their part in order to continue farming for their economy in an environmentally friendly way. Whether its done using state of the art Wastewater Treatment Plants or simply collecting rainwater off of their roofs to feed their crops, both urban and rural parts of Beijing are adapting to water scarcity. Any country that cannot afford a Wastewater Treatment Plant could easily learn from rural Beijing’s rainwater collection techniques and there is no reason that any place should be without clean drinking water and clean water for agricultural uses.

3. Greenhouse in Beijing

Image Sources:

1. "Introduction to Beijing Drainage Group," BDC, http://www.c-sewage.com.cn/cenweb/portal/user/anon/page/BeijingDrainage_CMSItemInfoPage.page?metainfoId=ABC00000000000009498 (accessed November 4, 9:30pm)

2. Zhang Feifei, "Innovations in Greenhouse Rainwater Harvesting System in Beijing, China," UA-Magazine, December 2007, http://www.ruaf.org/sites/default/files/UAmagazine%2019%20H7.pdf (accessed November 4, 10:00pm)

3. Sara Elliot, "How Greenhouses Work," How Stuff Works, 2008, http://home.howstuffworks.com/greenhouse.htm (accessed November 5, 6:00pm)

Information Sources:

Ji Wenhua, Cai Jianming, "Adapting to Water Scarcity: Improving Water Sources and Use in Urban Agriculture in Beijing," UA-Magazine, September 2008, http://www.ruaf.org/sites/default/files/UAM%2020%20-%20pagina%2011-13.pdf (accessed November 4, 8:00pm)

"Drinking Water Health Advisories," Water Quality Criteria US EPA, November 2009, http://www.epa.gov/waterscience/criteria/drinking/index.html (accessed November 4, 7:45pm)

"Economy of People's Republic of China," Wikipedia, November 2009, http://en.wikipedia.org/wiki/Economy_of_the_People%27s_Republic_of_China#Agriculture (accessed November 3 10:00pm)

Michael Levenston, "Water for Urban Agriculture," City Farmer News, October 2008, http://www.cityfarmer.info/?cat=315 (accessed November 4 9:00pm)

- Devon Holdsworth

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