Spatial and Temporal Dynamics of Crop Virtual Water Trade from Mexico to the United States

Abstract:

Global analyses have revealed virtual drains and gains of water between trade countries, for example in the trade relationship between Mexico and the United States (US). While this partnership has been identified as one supported by unsustainable irrigation water, the spatial understanding of its strain on water resources has remained at the national scale and without context of the factors driving the change. In this analysis, we focus on the evolution of Mexican agriculture in response to the North American Free Trade Agreement, expanding an understanding of how the trade agreement altered Mexican exports to the US and thereby amplified the associated environmental externalities in Mexico. Using a global process-based crop water model, we find that between 1994 and 2015, blue and green water consumed in production of crops increased by one fourth nationally, while water in export to the US doubled, outpacing production growth. Export of blue water in the form of berries alone increased more than five orders of magnitude; cereals, citrus fruit, fodder crops, nuts, other fruits, pulses, sugar, tubers, and vegetables also saw an increase in blue water export over the period. By identifying temporal and spatial heterogeneity of crops and associated water requirements driving virtual water exports, this study illuminates the hydrological impacts of trade agreements and the resulting impacts they can have on water sustainability, food security, and local communities.