By Dr. Upmanu Lall, director of the Columbia University Water Center
It’s well-documented that more regions of the United States will face increased water scarcity over the years to come, yet we often forget that an age-old problem — drought — magnifies the effects of water scarcity. A new report issued by the Columbia University Water Center, in conjunction with Veolia Water and Growing Blue, shows the water-scarce regions where drought is expected to have the greatest impact. The study reveals that some of the most iconic areas of the United States will be affected.
Of greatest concern are several notable metropolitan areas, including Washington, D.C., New York City, Los Angeles and San Diego. Taken alone, this could impact nearly 40 million Americans. However, this threat extends to numerous counties, many located in “America’s breadbasket” — Nebraska, Illinois and Minnesota — which produce almost 40 percent of the country’s corn.
In response, organizations are starting to develop tools designed to map water scarcity risk. The estimates used by these tools are typically based on supply and demand. It’s clearly important to understand any discrepancies between supply and demand, but without understanding climate variations, a major factor is being ignored.
In fact, these types of analyses actually understate the potential water risk that arises due to climate variations. Some areas which do not use more water than the existing supply will still be stressed by persistent shortage due to climate-related water conditions. As argued in the study:
A clear understanding of shortages induced by droughts, in terms of the magnitude, duration and recurrence frequency will better inform the water businesses and water-related sectors.
Drought will occur regardless of whether a region’s water resources are plentiful or stretched. And when drought hits a region with stretched resources, it magnifies preexisting problems — a scenario that will play out more and more as America’s demand for water outstrips its supply.
In order to take climate-related variations into consideration when factoring water risk, Columbia University researchers examined not only demand, but also variations in renewable water supply. Water risk was estimated using more than 60 years of daily precipitation data compared to the current water use pattern for U.S. counties.
Only precipitation that occurs directly over each county is considered, to reflect the dependence of that county on the need for storage or groundwater or water from other counties that may flow in through rivers or canals. We believe that this reveals a more accurate depiction of the discrepancy between water use and water availability, and the potential for spatial competition and conflict during times of water stress.
In the past, we’ve often talked about “growing green,” but this study reaffirms that the answer to the water scarcity problems of the future is to “grow blue.” We must change our current approach to water management, focusing on extracting more productivity out of each drop, reducing wastage and implementing new technologies and management processes that are focused on sustainability. Our problems of water scarcity can be mitigated, but it will take the will to do so; the result will be a better world for generations to come.
Dr. Upmanu Lall is the director of the Columbia University Water Center and a leading expert on hydroclimatology, climate change adaptation, risk analysis and mitigation.