Pumping water from the deep aquifer below the increasingly arid North China Plain has a hidden cost beyond the depletion of irreplaceable water resources, a new joint UK-China study reveals. Farmers are now pumping so much irrigation water from such deep levels, up to 70 meters-80 meters below ground in some provinces, that the energy required to drill the wells and run the diesel pumps accounts for more than half a percent of China’s total greenhouse-gas emissions.
Overall, farming accounts for 17–20% of China’s annual greenhouse-gas emissions, the study’s authors say. Pumping water for irrigation is one of farmers’ most energy intensive activities. The study, conducted by scientists from the Chinese Academy of Agricultural Sciences and the U.K.’s University of East Anglia, claims to be the first detailed estimate of greenhouse-gas emissions from groundwater pumping for irrigation. The authors say its shows that “significant potential exists to promote the co-benefits of water and energy saving in order to meet national planning targets”.
The scale of the challenge of realizing those benefits is that the current five-year plan aims to increase irrigation water use efficiency by 3% by 2015, emphasizing the importance of improving groundwater resource management to control over-exploitation. However, this is to be achieved whilst increasing total grain production by 13% to 450 million tonnes and decreasing national energy consumption per unit of GDP by 16%.