Understanding agricultural water footprint variability to improve water management in Chile.

Understanding water consumption is crucial for sustainable management of water resources. Under climate change scenarios that project highly variable water availability, the need for public policies that assure efficiency and equity in water resources is increasing. This work analyzes the case of the Cachapoal River agricultural basin (34°S 71°W), which presents temperature increases and a precipitation deficit, with a drought period that began more than eleven years ago having significantly decreased water availability. Water consumption in the basin for food production was determined from the agricultural water footprint (WF_agricultural), using the green (WF_green), blue (WF_blue) and gray water footprint (WF_gray) indicators, which were measured in the upper, middle and lower basin under conditions of climate variability (dry, wet and normal years). The greatest WF_agricultural was established in the dry year, with a total of 18,221 m³ t^-1, followed by 15,902 m³ t^-1 in the wet year and 14,091 m³ t^-1 in the normal year. Likewise, the greatest WF_blue and WF_gray, of 12,000 m³ t^-1 and 4934 m³ t^-1, respectively, were also observed in the dry year. The greatest WF_green, 2000 m³ t^-1, was calculated for a normal year. The 63% of agricultural area of the basin was covered by avocado (Persea americana), olive (Olea europaea), corn (Zea mays) and grape (Vitis sp) crops, which presented the greatest WF_agricultural. This water footprint data provides a quantitative basis for the assessment of water consumption and degradation, considering agricultural production and its multiple variables. The success of the application of these results lies in the use of indicators to understand change processes and complement future water allocation plans with more rational water management models.