Do Big Cities Cause Less Water Footprint than the Smaller Cities?

October 18, 2018

Due to the ever-increasing population, global sustainability is more important now than ever before. The world’s natural sources are being depleted right in front of our very eyes and if we want to carry on our civilizations as we know them, we need to do something about it.

A group of researchers from Penn State University carried out a study in which they analyzed the water footprint of 65 US cities that were mid-to-large sized. Some people in rural areas are still buying produce from across the world, and this just isn’t practical. By better understanding the urban water footprint, scientists can develop better tools to help solve these issues.

“We looked at the overall picture of water consumption,” explains Caitlin Grady. “Not just the water that comes out of your tap but also the water that goes into the food that each city produces and consumes, so it’s both the direct water use and indirect water use, which we call your water footprint.”

During the study, researchers thoroughly analyzed livestock, agricultural, and commodity flows as well as the relative virtual water contents. Putting all this information together they came up with an overall water footprint for each of the 65 cities. The results from the study may or may not surprise you, but on average, larger cities actually consume less water per capita than smaller communities.

According to Tasnuva Mahjabin, a doctoral student in civil engineering and one of the researchers working on the project, there are many reasons for this. “Water footprint consumption and production are tied to the changing composition of urban economic activities with city size, suggesting that large cities are more service-oriented with less prevalence to secondary sector industries,” says Mahjabin. “This allows large cities to have reduced water footprints by shifting water-intensive economic activities to less populated regions.”

Another thing the study revealed was that, on the whole, water sourced from groundwater or surface water resources had very little correlation with the population. Instead, it mirrored water-related weather patterns. Water used from precipitation, however, had both a negative and positive impact on consumption. It was negative in the sense that it increased diversity, but positive in the sense that transferred the dependence of food into the water footprint.

Las Vegas, for example, comes well below the average for water footprint production. Yet New Orleans is much bigger in comparison to its size. The results from the study may be used to benchmark cities and set new targets on how to best reduce water footprint across the board.

Moving forward, the researchers are hoping to strengthen their analyses incorporating more areas into the mix as well as including how much water consumption is required to provide electricity in different regions.

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