As Climate Changes, Researchers Look to Floods to Save California From Drought

A team of Stanford University researchers used computer modeling to map areas where increasing frequency and intensity of floods due to climate change might be used to stave off the ravages of drought in other parts of the state. 

Northbound traffic comes to a standstill on Interstate 5 freeway near the rushing water filled Los Angeles river near downtown Los Angeles on Dec. 9, 2018. (AP Photo/Richard Vogel)

(CN) — California Governor Gavin Newsom declared drought in two counties Wednesday and predicted others would soon join. He bemoaned the prospect of another period of drought only a few years removed from a five-year drought that strained the state’s water resources. 

A study published this week in Science Advances revealed one solution to the drought-like conditions and their increased frequency due to a changing climate is a counterintuitive one — floodwaters. 

The research attempts to create a framework for understanding and identifying floodwaters and their capacity to help recharge groundwater aquifers that are drawn upon more heavily during periods of surface water scarcity. 

By building an infrastructure capable of conveying floodwaters to aquifers, the state would not only help communities by stemming the destruction of rising waters while also helping replenish stored water.

“This is a large-scale picture of where floods occur and how much water can be stored,” said Xiaogang He, the lead author of the study. 

He gave an interview from Singapore, where he is currently an assistant professor in civil and environmental engineering at the National University in Singapore. Before that, he pursued floodwater research as a postdoctoral researcher at Stanford’s Water in the West program. 

“Based on my findings, most of the floodwaters will be located in Northern California, where they will see increased floodwaters compared to historical periods,” He said. 

While many see climate change as the hot getting hotter and the dry periods getting drier, many forecasters believe increasing wet weather will also come to parts of California as part of the shifting climate. 

He and the other researchers did not focus on the hows of creating the physical infrastructure necessary to convey floodwater to underground aquifers. Instead, they identified areas where such a plan is possible. 

“It’s more like policy recommendations so public agencies can prioritize investments,” He said. 

But along with looking at the possibility and investment prioritization, the researchers grappled with the limits of the floodwater to groundwater aquifer solution as well. 

“Integrating managed aquifer recharge with floodwaters into already complex water management infrastructure offers many benefits, but requires careful consideration of uncertainties and constraints,” said Stanford professor and study co-author David Freyberg. “Our growing understanding of climate change makes this an opportune time to examine the potential for these benefits.”

One of the major constraints according to the writers, is the complex series of water laws and water rights that makes navigating the regulatory aspect of groundwater recharge so perilous. 

“In addition, policymakers will have to establish certain thresholds that aim at quantifying floodwater,” He said. “Different water managers and stakeholders have different definitions of what constitutes floodwaters, which could affect the amount taken from a certain area.”

But the regulatory hurdles are not the main impediment, according to the study. 

“The most dominant part of uncertainty comes from climate models themselves,” He said. “There are a bunch of climate models developed by different countries, different institutions and even using different physics, and this creates a huge amount of uncertainty about the availability of floodwaters.”

The team used a hybrid computer model that integrated climate models but also hydrological data to run several different climate models in an attempt to calculate how much water would be available for recharge out to 2090. 

Another uncertainty is how much the United States and other countries will succeed at curtailing greenhouse gas emissions. Many climate models are based on the status quo of emissions, but if countries reduce emissions by the amounts they have pledged as part of the Paris climate accord, then the models shift dramatically. 

Finally, constraints exist in terms of the physical infrastructure and associated costs. 

“The question becomes whether there is the capacity to deliver or transfer floodwater,” He said. 

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