Thompson Rivers University

Rain research: Mitigating floods, examining climate change

  Posted on: April 15, 2019

Dr. Darryl Carlyle-Moses

Dr. Darryl Carlyle-Moses’ stemflow research has applications in urban planning and larger discussions around mitigating rain-heavy weather events and climate change.

When a raindrop falls alone in a forest, and nobody is around to see it, where does it go? And how much builds up?

Arts faculty member Dr. Darryl Carlyle-Moses’s research focuses on that and most other things relating to rain and trees. The amount of water that runs down a tree trunk and collects at the base is called stemflow, and that’s his specialty.

He just wrapped up the exciting experience of sharing his research as an invited speaker at the European Geophysical Union General Assembly 2019 in Vienna, Austria. Carlyle-Moses presented his paper, Stand-Scale Metrics for Expressing Stemflow Commensurate with its Ecohydrological Importance, which opened the conference session on Water and Solute Fluxes Affected by Vegetation Canopies. Carlyle-Moses was one of 16,273 scientists in attendance from 113 countries. 

Carlyle-Moses has been teaching at TRU since 2004, and conducting local research in places like McArthur Island Park, Mayson Lake and areas on campus.

His field work while pursuing his PhD in the Sierra Madre Oriental mountain range in Mexico kickstarted a long road of research into the interaction between rainfall and ecosystems. He now specializes in forest hydrology, specifically what he calls eco-hydrology.

Examining stemflow, how that water affects ecosystems and how ecosystems influence water storage and movement is the cornerstone of his research. This work can help  urban planners understand how to mitigate flood risks from intense rainfall and how to best select trees in landscaped areas with limited irrigation—all by using trees and their natural ability to concentrate water at their bases.

According to Carlyle-Moses, much of the research done in forest hydrology doesn’t pay enough attention to stemflow.

“So much of the literature has been ignoring stemflow, because it’s such a small percentage of total rainfall. But it’s really, really important because it can be such a large volume delivered to a very small area of the ground,” he said.

For his paper, he studied 36 mature forests around the world and found that in all cases, the most water being delivered across the forest floor after rainfall was at the tree base. The largest depth of water was all from stemflow.

Closer to home, Carlyle-Moses’s work still applies. Stemflow affects many aspects of urban planning like mitigating flooding during heavy rainstorms and, with the right type of tree, stemflow can provide trees with large amounts of water, which is important in areas where irrigation is limited or non-existent. Additionally, trees and stemflow figure into larger discussions around climate change.

“Environmentalists are coming in from forests and researching where ecosystem processes are still happening, in cities. Figuring out the function of trees and finding out how they can be beneficial during heat waves or large rainfalls is huge. Understanding the true role of trees in cities and how to manage trees is an enormous benefit to everyone,” he said.

Learn more about Geography & Environmental studies at TRU