If past trends in greater Phoenix – agricultural land transitioning to urban – the area is on track to groundwater “safe yield”, according to new research by an Arizona State University team:
Under (business as usual) conditions where population is expected to increase and agricultural activities to gradually decrease, our results indicate a reduction in the use of groundwater of ~23% that, in turn, will likely allow achieving safe-yield. If the decrease in agricultural activities will be less drastic or remain constant in time (i.e., more food will be produced locally), additional water from more energy-intensive water sources (groundwater and CAP) will be needed.
A shift in the trend – less ag land decline – makes it less likely that Phoenix would meet the goal, the researchers found. A shift to more renewables means an even better prognosis for groundwater, given the significant use of water for power plant cooling. And it probably goes without saying that a multi-decadal drought would make things harder.
The paper is Guan, Xin, et al. “A metropolitan scale water management analysis of the food-energy-water nexus.” Science of The Total Environment 701 (2020): 134478. Found behind a paywall here.
All you have to do is go to the Valley of the Sun and drive around. See for yourself the explosive housing expansion in both the east and west valley, the lost farm land (permanently), together with the population growth and it will be hard to believe there isn’t a tipping point between “safe yield” and negative water reserves.
I’m curious about the role of agriculture as a source of “local” food supply; especially as rising temperatures reduce production. It seems that ag in Colorado is an extractive industry. I’m told that some 90% of food consumed in Colorado is imported. That is, our local markets sell products that originate outside the state. It turns out Asia is a growing market for Colorado beef. We import a lot of meat from Australia and New Zealand as well as South America.
In my local Crystal River Valley, almost all the beef is exported for finishing and outside markets. The farmers’ income derives from local water use (with some very senior rights) and local soil and sunshine that produces hay. The animal’s summer gazing is on government land. The farmers are a small part of the local economy but by far the biggest water users.
My point is that there is no local “food” penalty for paving over local farms. I wonder how that factors into the research on local water consumption.