FINDING BALANCE: Drought is only part of the story

U of A project applies crowdsourcing to rain data



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Arizona has been in a drought since the late 1990s and it’s been particularly dry in Cochise County, according to Mike Crimmins, an associate professor at the University of Arizona who sits on the governor’s drought task force.

“You guys just can’t catch a break,” he said. When much of central Arizona picked up some winter precipitation this year, Cochise County was left high and dry.

Even with fairly average monsoon activity, which has been spotty but normal, rainfall in the winter months has been slim, Crimmins said. The U.S. Drought Monitor has Cochise County fluctuating between severe and extreme drought conditions.

But drought cycles spanning decades are not unusual, tree rings show the ebb and flow of dry and wet periods over several hundred years, he said. In the 1950s there was a drought that was a bit more severe than the current one, yet precipitation is only part of the story.

“It’s much warmer than it has been in the past,” Crimmins said. That’s the sneaky thing about this drought and its impact on water, higher temperatures can increase evapotranspiration and also lead to more groundwater pumping.

For Tucson, 2012 was the second warmest year on record, nearly matching 1989, Crimmins said. But it’s not just one year, almost every year since the late 1980s has been above average, with temperatures increasing more rapidly in the last two decades.

This trend has started to support the idea of “the new norm,” Crimmins said. So while we may be in the middle of a drought cycle that will eventually give way to a wet period, that doesn’t mean average temperatures will go back down.

“We’re having to really pay attention to where does what go? What happens to water when it’s much warmer,” Crimmins said. The fate of water in a complex system when it becomes warmer is not clear.

Groundwater pumping for domestic use goes up when it gets warmer and drier, Crimmins said. It also increases evaporation and transpiration, though its impact on plants is not linear.

Different plants use water in different ways and some shut down completely in certain times, he said.

It also impacts mitigation efforts such as rainwater harvesting and stormwater recharge, which depend on rainfall. Crimmins said the lack of winter precipitation can necessitate a larger storage capacity for rainwater systems.

To see updated drought information across the country, go to www.droughtmonitor.unl.edu.

 

Citizen scientists collect rain data

Anyone who has experienced a monsoon in Arizona can tell you that buckets of rain can fall on one person’s house, while their neighbor’s home, only a mile or two away, is bone dry.

The spottiness of these summer storms inspired the creation of Rainlog, which was founded by Crimmins and University of Arizona hydrology and water resources department chair Gary Woodard in 2005. Instead of relying on one or two official collection sites, Rainlog uses a network of volunteers to collect its data.

It began to collect data in the Sierra Vista area but has expanded to include more than 2,000 citizen scientists worldwide, Woodard said. Residents can also sign up to receive emails detailing the rain collection of volunteers who live nearby.

“It’s near and dear to our hearts, we keep at it, even though it’s essentially unfunded,” Woodard said.

Right now, there are 58 rainloggers in Sierra Vista and some in Cochise County who have contributed their personal logs dating back decades.

To take a look at the data, learn how to become a volunteer, or sign up to get email updates, go to www.rainlog.org





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