Groundwater Overdraft in Mexico: Climate, Energy, and Population Drivers
University of Arizona
Over 100 of Mexico?s principal aquifers are overexploited, up from one-third of that number in 1975. This paper assesses data for 288 aquifers across Mexico and considers the groundwater balance implications of changing climate, electrical energy supply, and growing population. Climate change and variability of surface water intensify groundwater use by increasingly shifting consumptive demand to groundwater while the impacts of climate change on recharge are poorly understood. Electrical energy supply and pricing are primary enabling factors behind groundwater pumping for irrigation ? the largest user of groundwater in Mexico. Three of the four states with the highest energy demand for irrigation pumping are located along Mexico?s border with the United States, where energy and groundwater demand continue to rise. The rise in commercial export-oriented agriculture raises questions about trade policies with the U.S. that appear to increase agricultural water demand in Mexico. At the same time, groundwater is an important source of urban water supply, placing cities in competition with agriculture for groundwater. Policies to make an impact on groundwater overdraft must focus on the water-energy nexus. Off-peak (night-time) energy use for pumping has increased significantly since time-of-day metering and differential tariffs were introduced starting in 2003, with significant negative implications for groundwater sustainability. Assessments of groundwater titling and user-based groundwater management initiatives suggest that awareness of groundwater depletion is increasing; however, groundwater sustainability remains an elusive goal.