Thirsting for Answers

It’s a conundrum. According to the Desert Research Institute, the Colorado River (to which the Gunnison River is one of the largest tributaries) delivers water to 40 million people in seven states, not only for drinking but also to grow food for the entire country. The problem is that the river is not keeping pace with the region’s thirsty demands.

The western U.S. is plagued with a historic drought. Less snowfall in the mountains is drying up the river’s main water tap. And climate change is making future precipitation trends uncertain.

Fortunately, a large team of scientists is on the case. One is Rosemary Carroll, PhD, a research professor at the Desert Research Institute. She’s studied mountain hydrology in the East River Watershed of the Upper Gunnison Basin for more than a decade. She hopes to understand the sources of streamflow in the mountains around RMBL — like snowmelt, rainfall, and groundwater — to know how the streamflow responds to changes.

When a friend introduced her to Lawrence Berkeley National Laboratory’s deputy lead, her hydrology expertise found an outlet at LBNL’s Watershed Function Science Focus Area. In 2014, Dr. Carroll was contracted to set up a stream gauge network to measure stream discharge. Now, a team of field researchers helps gather the data while she builds computer simulations to analyze the water budget of her study domain.

Researching mountainous waterflow has led her to conclude that water beneath the earth’s surface deserves more attention. It isn’t snowmelt alone that fills streams. Groundwater contributes a significant amount to streamflow. In fact, it helps buffer streams in low snowmelt years.

In the last 15 years, Dr. Carroll’s computer models have indicated a downward trend in groundwater, largely due to overlapping extreme climate events. For example, the effects of 2012, a very dry year, accelerated in 2018 when low snow conditions overlapped with multiple summers of low-to-no monsoons. It took a large release of groundwater to replenish the streamflow, and the system has yet to recover.

Collecting mountainous groundwater data is no small task, given the expense and logistics of drilling groundwater wells, the steep and dangerous topography, and brutal winters to contend with. But scientists now have better tools yielding better data. Durable automatic collection instruments, satellite data, age dating, and geochemistry have made the process easier.

What’s more, multidisciplinary collaborations are drilling deeper for answers. Hydrologists are working with ecologists, geochemists, computer scientists, and remote sensing scientists to approach water resource solutions from all angles.

Better science, better tools, and better partnerships are the resources that will ensure our water will be here when we need it. We just need to tap them.

Rosemary Carroll, PhD, is a research professor in the Division of Hydrologic Sciences at the Desert Research Institute in Reno, Nevada. She specializes in integrated hydrologic systems of mountainous watersheds, where she investigates how snow, soil, bedrock, and vegetation interact to govern the timing and quantity of streamflow. Much of her work is grounded in long-term, interdisciplinary collaboration with the U.S. Department of Energy’s Watershed Function Science Focus Area, which has generated robust observational and modeling frameworks in the Upper Gunnison Basin to assess critical zone feedback, groundwater-stream interactions, and system responses to warming and disturbance.

Article written by RMBL contributor, Carol St, George