title: Impacts of changing cropping pattern on virtual water flows related to crops transfer: a case study for the Hetao irrigation district, China.
abstract: BACKGROUND
  Analysis of cropping patterns is a prerequisite for their optimisation, and evaluation of virtual water flows could shed new light on water resources management. This study is intended to explore the effects of cropping pattern changes between 1960 and 2008 on virtual water flows related to crops transfer in the Hetao irrigation district, China.
  
  
  RESULTS
  (1) The sown area of crops increased at an average rate of 3.57 × 10(3) ha year(-1) while the proportion of sown grain crops decreased from 92.83% in the 1960s to 50.22% in the 2000s. (2) Virtual water content decreased during the study period while net virtual water exports increased since the 1980s. (3) Assuming that the cropping pattern was constant and was equal to the average 1960s value, accumulated net virtual water export in 1980-2008 would have been 4.76 × 10(9) m(3) greater than that in the actual cropping pattern scenario.
  
  
  CONCLUSIONS
  Cropping pattern changes in the Hetao irrigation district could not only be seen as resulting from the pursuit for higher economic returns, but also as a feedback response to limited water resources. A systematic framework is still needed for future cropping pattern planning by taking food security, continued agricultural expansion and other constraints into consideration.
authors.affiliation: Institute of Soil and Water Conservation, Northwest A&F University, Yangling, 712100, China; Institute of Water Saving Agriculture in Arid Regions of China, Northwest A&F University, Yangling, 712100, China; National Engineering Research Center for Water Saving Irrigation at Yangling, Yangling, 712100, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.forename: Pute
authors.initials: P
authors.lastname: Wu
authors.forename: Yubao
authors.initials: Y
authors.lastname: Wang
authors.forename: Xining
authors.initials: X
authors.lastname: Zhao
authors.forename: Shikun
authors.initials: S
authors.lastname: Sun
authors.forename: Xinchun
authors.initials: X
authors.lastname: Cao
mesh_terms: D057914:Agricultural Irrigation / Q000191:economics / Q000379:methods*; D002681:China; D018556:Crops, Agricultural; D008962:Models, Theoretical; D013997:Time Factors; D014872:Water Movements
keywords: cropping pattern; grain crop; irrigation area; non-grain crop; virtual water