University of California


Harter, Thomas

Presentation Title
For want of food: Groundwater and Agriculture
University of California, Davis
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Food, feed, fiber, and (bio)fuel production in agriculture consumes nine out of every 10 liters of freshwater consumptively used by humans - the remainder being consumptive water losses in industrial and domestic water uses. Irrigated agriculture produces 40 percent of the global food supply. In many irrigated regions throughout the world - Southwestern U.S., China, India, the Mediterranean region, Mexico - groundwater constitutes from one third to more than two thirds of all irrigation water. More importantly, groundwater provides a stable source of water against local and global climate variability. World population growth and increasing economic output not only in developed countries, but also in Latin America and especially in India, Southeast Asia, and China continue to heighten demands for food production. Water and especially groundwater use for food production has therefore seen tremendous increases over the past decades, first in the U.S. and in southern Europe, and over the past thirty years also in India, China, North Africa, the Middle East and elsewhere. In turn, groundwater overdraft and groundwater quality degradation in agricultural regions have become issues around the globe, and are now closely linked to global long-term food security in both irrigated and rain-fed regions. I suggest that long-term global food security, and with that the livelihood of the agricultural community must be considered as the driving rationale for sustaining agricultural groundwater resources for long-term food production. But the complexity of the link between sustainable groundwater resources and food security is challenging both, our understanding of its true global significance and our ability to develop comprehensive, adequate technical and policy solutions. Disciplinary scientific and legal isolation between watershed management, groundwater quality and quantity management, and agricultural management, disparateness between science, policy, and education, and the geographic and socio-political isolation of stakeholders that arises from the fact that groundwater is intrinsically a local or regional, common pool resource are major hurdles in working toward a global infrastructure that can efficiently support sustainable groundwater in agriculture at a global scale. Recently, much local, national, and global efforts have been initiated toward meeting these challenges, especially with respect to surface water. A broader initiative is needed to also establish a global network of regional and (trans-)national efforts that can effectively help formulate, assess, and meet the wide range of challenges in agricultural groundwater quantity and quality management as a critical part of managing our water resources in agriculture. Agricultural groundwater management and policy must also strike a balance with competing, but related needs for urban growth and environmental sustainability in a world of global change and limited land and energy resources.

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