The impact of the U.S. beef network on water resources

As food systems in the U.S. become more interconnected and complex, products — beef products in particular — often impact the environment in previously unknown ways. 

Water is needed throughout the entire food supply, but the beef industry is the least efficient at using it, scientists have found.  Now, University of Pittsburgh researchers have designed a model that reports the industry's impact on virtual water flows – the hidden movement of water in food production — by tracing beef supply chains from calf production to beef consumption at the county level. 

The study was funded by the U.S. National Science Foundation, and results are published in Environmental Science and Technology. 

"Understanding beef demands and the spatial distribution of both feed and cattle production are key for evaluating the environmental sustainability of food systems and developing improvement strategies," said Pitt civil and environmental engineer Vikas Khanna.  

All animal production requires great quantities of water, with the vast majority used to produce feed. The irrigation process for feed requires blue water, water found in surface and ground reservoirs. Using blue water exclusively can lead to environmental issues such as water depletion, salinization, and soil degradation. 

The researchers used an optimization-based framework and publicly available datasets on supply and demand. Their model showed a disconnect between consumption and production counties, with more than 22 billion cubic meters of blue water transferred in 2017 alone. For perspective, the Great Salt Lake has 19 billion cubic meters of water.  

"Typically, real-world networks have a skewed degree of distributions with few connected intersections," explained Khanna. "We observed this in our network as the majority of counties have few connections, while a small number of counties have a large number of connections." 

According to Bruce Hamilton, a program director in NSF’s Directorate for Engineering, "This research reflects the complexity of environmental systems and how important it is to take that complexity into account with a systems perspective."

Next, the team plans to apply the framework to understanding the environmental impacts of other animal-based production practices, and to identifying improvement opportunities.