DO WATER-RICH REGIONS HAVE A COMPARATIVE ADVANTAGE IN FOOD PRODUCTION? IMPROVING THE REPRESENTATION OF WATER FOR AGRICULTURE IN ECONOMIC MODELS

With growing demand for fresh water and uncertain supplies, there is an increasing concern about future water scarcity. Since most freshwater withdrawals are for agriculture, reliance on water embodied in imported food (trade in 'virtual water') is a possible strategy to provide food to water-stressed regions while conserving their scarce supply for other purposes. To evaluate this proposition, we extend a model of interregional trade by (1) defining endowments of water that cannot be exceeded, (2) allowing simultaneous operation of rainfed and irrigated agriculture, and (3) distinguishing sub-regional endowments within a larger economic region. An application to the Mexican economy compares region-specific water abundance with economic comparative advantage under alternative scenarios. We conclude that the water-rich regions of Mexico are relatively high-cost producers of food and that they do not pick up the slack even when the lowest-cost Mexican regions are constrained by binding water constraints.