@article{Biewald:332045,
      recid = {332045},
      author = {Biewald, Anne and Lotze-Campen, Hermann and Rolinski,  Susanne and Hoff, Holger},
      title = {The impact of trade on local green and blue water  availability},
      address = {2011},
      pages = {21},
      year = {2011},
      note = {Presented at the 14th Annual Conference on Global Economic  Analysis, Venice, Italy},
      abstract = {International trade of agricultural goods exported from  water abundant to water scarce regions can, in theory,  alleviate water scarcity problems, which is a widely and  controversely discussed issue in the virtual water  literature. But how much can trade really help to solve  water scarcity problems? And more importantly does trade of  virtual water save the valuable blue water which can be  rededicated to other purposes than agriculture or does it  rather let green water go unused for which an application  to other usages is often difficult? To address these  questions we use two models: First, MAgPIE trade (Model of  Agricultural Production and and its Impact on the  Environment), to give us explicit trade and production  patterns for food crops. And second, LPJmL a dynamic,  spatially explicit, global vegetation and agricultural  model with closed water and carbon budgets, which simulates  the blue and green virtual water content of the produced  food crops. To assess the effect of trade on agricultural  production and water availability, we compare two scenarios  for the year 2005: one in which trade is completely  disabled and one with a business as usual scenario. The  difference between the two scenarios tells us how  production patterns change when no trade is possible.  Coming from there and using the explicit virtual water  contents of LPJmL, we can calculate how much virtual water  is saved by allowing trade. We can also determine how much  blue water has been saved on the regional and the global  level by this trade. MAgPIE trade gives us additionally  spatially explicit patterns of agricultural production.  Using the difference in the production of the two  scenarios, we can now determine how production patterns  change when no trade is possible. LPJml provides than  consumptive green and blue water use for each of the  produced crops. Combining the outputs of both models, we  can now determine where and how much of green and blue  water use increased or decreased when trade is eliminated.  This information is already interesting but does not tell  us if the important blue water has been saved in water  abundant or in water scarce regions. Using the MAgPIE trade  output of cell-based water shadow prices (which is a  measure of water scarcity), we develop an indicator of the  significance of water saving. This significance indicator  can answer the question if and where blue water is saved.},
      url = {http://ageconsearch.umn.edu/record/332045},
}