Variability in the Water Footprint of Cereal Crops, Cachapoal River, Chile

The water footprint was calculated to evaluate the effects of climate variability on the water consumed during the production of cereals. This methodology considered three precipitation scenarios: a) rainy year, b) normal year and c) dry year. It also included two yield conditions - constant and a 20% reduction (projecting for the effect of climate change)- for three sections of the Cachapoal River basin. In addition, virtual and apparent water productivity were calculated to demonstrate the effect of climate variability on water productivity of cereal crops. The analysis of percentiles found that the year 2005 corresponded to a rainy year, 2006 to a normal year and 2007 to a dry year. Under constant yield conditions, the water footprint of the cereals was larger during the rainy year (1 064 m3/ton), while under reduced yield conditions it was larger during the dry year (1 633.9 m3/ton). For both conditions, the largest blue water footprint estimated corresponded to a dry year and the largest green water footprint to a rainy year. Nevertheless, no differences among the sections of the basin were observed. During a rainy year, the largest amount of virtual water (14 325 000 m3/year) would be exported and the lowest apparent water productivity (92.8 $/m3) would be produced. This information is crucial to develop sustainable agricultural systems.