Scientists look at how climate change could impact landscapes

Novel lab experiments at the University of Oregon have allowed geologists to observe the formation of ridges and valleys in real time.

The new research makes the interplay between two complex fields of study -- climatology and geology -- at least marginally intelligible, allowing scientists to predict how climate change might affect landscape formation.

To predict landscape formation, you have to understand landscape formation. It's a daunting task. Scientists have long struggled over how the near-perfect patterns of hills and valleys come to be, the result of millions of years of meteorological and biological forces.

To simplify the process of landscape formation to the point where it could be recreated and studied in the lab, researchers boiled it all down to the interplay between two main processes -- runoff and soil movement.

Runoff consists of the forces exerted on the landscape by precipitation as it lands, collects and cuts through the environments. This is mostly the meteorological side. Soil movement, on the other hand, is mostly the biological side. It consists of the disturbances caused by burrowing gophers, tree roots, digging insects and frost.

Generally speaking, runoff carves and soil movement fills. Together they sculpt. The interplay between these two types of influence (a tango of sorts), accounts for the rising and falling of ridges and valleys.

In the lab, researchers employed periodic misting to mimic runoff. Sharp blasts of larger water droplets replicated the effects of soil movement.

"In our experiments we were able to dictate the processes involved and observe the landscapes that arise," Oregon doctoral student Kristin E. Sweeney said in a press release. "We were able to directly control the various processes. Previous research has only attempted to replicate channel processes -- what the rivers do. We essentially started from scratch, working to see the movement of sediment slopes in a realistic way."

It's the tango of so-called diffusive and advective processes that explains the rhythmic patterns people see from their airplane windows as they fly over the badlands of Montana and South Dakota, or peer down upon the hills and valleys of Oregon.

The new study, published this week in the journal Science, offers the first physical documentation of hill and valley formation. In doing so, researchers can now better predict how climate changes might affect landscape patterns.

"The contribution of hill slopes to drainage basin formation has not been widely appreciated," Joshua J. Roering explained. "The more water on landscapes, the more vegetation, the more varmints and more life that is out there doing hill slope work. If you make things drier you tend to decrease the vigor of hill-slope processes and drainage networks should reflect that."