by Robert Sanders, UC Berkeley Media Relations
A $4.9 million grant will fund a study of the nearly 10,000 -square-kilometer Eel River watershed in Northern California, home to the UC Natural Reserve System's Angelo Coast Range Reserve. Led by UC Berkeley scientists, the five-year study will examine how the vegetation, geology and topography of the Eel affects water flow all the way to the Pacific Ocean.
What the researchers uncover will help improve global climate models and modeling tools that can be used by state or regional decision makers to guide planning. Their discoveries may eventually allow scientists to predict the impact of changing climate and land use on future droughts, floods and supplies of water for drinking and agriculture.
The National Science Foundation establishes the Eel River Observatory as one of nine Critical Zone Observatories. All focus on the so-called "critical zone": the thin veneer of Earth, from the bottom of groundwater basins to the treetops, that is critical to aquatic and terrestrial life as the source of fresh water and where soils are formed from rock. The observatory is the direct result of decades of water research conducted at Angelo Reserve.
The Eel River is increasingly under pressure because of illegal marijuana cultivation, wine grape growing and other uses that extract water from the river and threaten one of the state's largest coho salmon runs. In addition, warming waters in recent years have led to outbreaks of blue-green algae that produce toxins that have killed dogs that licked their fur after emerging from the water. The river is currently beset by low water flow because of the driest winter in decades.
"Whatever the agricultural use in the future, we will see increasing demands on a decreasing water resource," said observatory director William Dietrich, UC Berkeley professor of earth and planetary science and an expert on topography, landscapes and landslides.
For more than 20 years, Dietrich and other UC Berkeley scientists, including river ecologist Mary Power and atmospheric scientist Inez Fung, have studied the Eel River watershed within the Angelo Coast Range Reserve, part of the University of California's Natural Reserve System. A 2006-2010 project called Hydrowatch, funded by the W. M. Keck Foundation, allowed geologists, biologists, climate scientists, and chemists to place sensors over a small portion of the watershed to measure soil and rock moisture, water transport in trees and transpiration from leaves, in essence tracing the water and dissolved minerals and gases as they moved through the mixed hardwood-conifer ecosystem.
"The Keck Hydrowatch grant got us following the water and thinking about how topography affects the return of moisture to the atmosphere, and suggested the need to look inside hillslopes to understand atmospheric moisture, river flow and chemistry, ecosystems dynamics, and coastal ocean productivity," Dietrich said. "This NSF funding will allow us to expand our research area to the entire Eel River watershed, totaling nearly 10,000 square kilometers, and begin to look at the neighboring Russian River watershed."
Dietrich refers to everything that moves through the landscape – water, plants and animals, microbes, dissolved minerals and gases in the water, sediments and the total energy flowing through the watershed – as "currencies," analogous to the money that flows through a country's economy. The Eel River Observatory will focus on how the soil, forest and river "economy" interact with these currencies, including determining the flow maintained in rivers through drought, and the delivery of nutrients to the sea. Of particular interest is the so-far unexplored landscape beneath the hillside surface and below the soil mantle.
"Until now, we have been focused on this hillside in the Angelo Reserve, finding out how hills determine the return of gases to the atmosphere through plants, the amount of water available to plants and how much water is released to the stream," he said. "Now we will begin to look at how hillside dynamics influence what is delivered to the ocean, and how coastal productivity may be influenced by stream dynamics."
Key questions include: How does the underlying rock affect how much water is stored underground for plant use, and how might that affect plants' susceptibility to seasonal drought and long-term climate change? How do underground microbes influence gases – oxygen, carbon dioxide, and hydrogen sulfide – and dissolved minerals available to plants through their roots? How does hillside storage of water affect the amount of water in the streams during California's dry summers? Is there a tipping point beyond which climate change and land use change will irreversibly alter the river and coastal ecosystem?
"With anticipated increases in climate extremes, especially extended drought, and accelerating societal demand for water. We will focus on filling the gaps in our knowledge that not only inhibit our ability to forecast the magnitude of future change in the ecosystems, but even the direction of that change," Dietrich said.
"NSF awards grants for four new critical zone observatories to study Earth surface processes," National Science Foundation, January 15, 2014
Mapping the Future, hour-long documentary on Angelo Coast Range Reserve research