Water scarcity is an enormous challenge in many parts of the world, with many of the world’s most important aquifers being drained much faster than they can be replenished. These trends in water availability will have effects on food production systems, water-borne illness patterns, and other water-related diseases. For example, the aquifer under the North China Plain, where half of China's wheat is grown, is falling at up to three meters/year, and it is estimated that each year 300 million Indians and Chinese are being fed on fossil water that is not being replenished. Demographic changes are driving sharp increases in global water demand at a time when climate change promises to increase water scarcity in a variety of ways, including more extreme forms of precipitation, dry areas becoming drier, earlier spring runoff from winter snow pack, loss of glacial contributions to dry-season flow, sea level rise and inundation of coastal aquifers with salt water, and hotter temperatures leading to increased evapotranspiration.
These complex changes in quantity, quality, and timing of water availability, overlaid on significant existing water scarcity and increasing demand, are likely to impact food production, water-borne disease exposure, and water-related diseases. Changes in land use (e.g., deforestation) also impact water quality and quantity and exposure to water-borne disease in ways that are inadequately understood. Research to better characterize these challenges and identify approaches to reducing vulnerability is urgently needed.