Ground water is the primary source for both municipal and industrial water supplies throughout the world. Some of the world's largest and fastest-growing cities depend heavily on natural aquifers that collect and store ground water. When ground water supplies are withdrawn faster than they naturally replenish, problems arise. In this video segment adapted from Last Oasis learn how Mexico City's growing population is depleting local ground water and how this depletion is largely responsible for causing historic buildings to lean as the ground beneath them sinks.
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