Rain lingers over parts of California from big, slow-moving storm systems that sometimes dump 30 inches of rainfall in just 20 hours. This wetness can take its toll on infrastructure such as levees, roads, and water-treatment plants, while also leaving behind a smearing of salt and minerals in what appears to be an invisible film on everything from sidewalks to roads to the state’s waterways.
And while experts say it’s common in California–and in other Southern states–the problem has gotten worse in the past few years. But now, a team led by researchers at the University of California, Davis, have found the problem has deepened since the 1970s, as well.
“The precipitation we typically see in California in the winter is much more intense than what we’ve seen in the winter over the past few decades,” said Steven M. Anderson, a professor of civil and environmental engineering who is the leader of the team. “That’s a huge trend line, and it’s something we’ve not really seen.”
The team’s findings on precipitation trends in California were published in the April issue of the Journal of Climate.
“This is more than a problem of storms,” Anderson said. “It’s a problem of how much precipitation ends up in the storm systems that bring it down to the coast.”
According to Anderson and his co-authors, who included Mark E. Friesen, a professor in the school’s Department of Civil and Environmental Engineering, the problem could stem from rising temperatures and changes in rainfall and atmospheric circulation patterns.
“There’s a new study out this week from the National Science Foundation that we’ve been following in the Geophysical Research Letters journal,” Anderson said. “It’s suggesting that in fact the rainfall in inland California has been increasing substantially in the past 40 years.”
Anderson said while he wasn’t surprised the new study showed an upward trend in California’s inland precipitation, the study seemed to indicate that something the state did in the 1970s was to start to shift rainfall patterns eastward.
“The question that we asked