Event Title

Monitoring Channel and Vegetation along the Free-Flowing Yampa River

Presenter Information

Michael Scott

Location

USU Eccles Conference Center

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Abstract

Much of what we know about large river ecosystems comes from work on regulated rivers. The scarcity of quantitative information about pre-development conditions on these rivers restricts understanding of the full range of ecological responses to regulation and constrains predictions of future regulated-river behavior in the context of climate change, continued water development, management and restoration efforts. River regulation in the Colorado River basin has changed the magnitude and timing of water and sediment delivery to downstream reaches. Channel narrowing is a widely documented morphological adjustment of stream channels to natural or anthropogenic changes in stream flow and sediment flux, including establishment of vegetation on formerly active channel features. The Yampa River is perceived as one of the least regulated rivers in the Colorado River basin. We examine the degree to which the Yampa has been altered by water development. Further, we mapped geomorphic features and compared riparian vegetation across three distinct channel planforms. Of seven major Colorado River tributaries, the Yampa is the fifth largest in terms of virgin mean annual discharge. However, it is has the second smallest degree of flow regulation, expressed as the percent of virgin mean annual discharge capable of being stored, and retains a high degree of flow variability. Analyses indicate significant differences in plant species cover and composition among channel types (p=0.001). Significant differences in vegetation also were related at a finer scale to specific geomorphic surfaces (e.g., active channel, active floodplain), reflecting distinct geomorphic processes and physical environmental conditions. Finally, there were no significant changes in vegetation cover or frequency on specific active bar surfaces over four years implicating the importance of flow variability. This information provides a baseline for gauging future channel change and can be used to tailor change-detection monitoring to hypothesized geomorphic and vegetation changes in specific hydrogeomorphic settings.

Comments

Michael Scott received his Ph.D. in Forest Ecology from Michigan State University. He did Post-doctoral work at the University of Georgia and was a Research Associate at Oregon State University. He was a Research Ecologist for the U.S. Geological Survey in Fort Collins, Colorado for 25 years and is now a USGS Riparian Ecologist, Emeritus and adjunct faculty in the Watershed Sciences Department, Utah State University. Enduring research interests include the biology and ecology of cottonwood and how stream flow, channel change, and vegetation dynamics interact to create and sustain western riparian ecosystems. Mike has conducted basic and applied research on cottonwood ecosystems of the upper Missouri River in Montana for over 20 years and more recently has been involved in developing long-term riparian monitoring protocols for large river in the Colorado River basin.

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Oct 22nd, 3:30 PM Oct 22nd, 4:00 PM

Monitoring Channel and Vegetation along the Free-Flowing Yampa River

USU Eccles Conference Center

Much of what we know about large river ecosystems comes from work on regulated rivers. The scarcity of quantitative information about pre-development conditions on these rivers restricts understanding of the full range of ecological responses to regulation and constrains predictions of future regulated-river behavior in the context of climate change, continued water development, management and restoration efforts. River regulation in the Colorado River basin has changed the magnitude and timing of water and sediment delivery to downstream reaches. Channel narrowing is a widely documented morphological adjustment of stream channels to natural or anthropogenic changes in stream flow and sediment flux, including establishment of vegetation on formerly active channel features. The Yampa River is perceived as one of the least regulated rivers in the Colorado River basin. We examine the degree to which the Yampa has been altered by water development. Further, we mapped geomorphic features and compared riparian vegetation across three distinct channel planforms. Of seven major Colorado River tributaries, the Yampa is the fifth largest in terms of virgin mean annual discharge. However, it is has the second smallest degree of flow regulation, expressed as the percent of virgin mean annual discharge capable of being stored, and retains a high degree of flow variability. Analyses indicate significant differences in plant species cover and composition among channel types (p=0.001). Significant differences in vegetation also were related at a finer scale to specific geomorphic surfaces (e.g., active channel, active floodplain), reflecting distinct geomorphic processes and physical environmental conditions. Finally, there were no significant changes in vegetation cover or frequency on specific active bar surfaces over four years implicating the importance of flow variability. This information provides a baseline for gauging future channel change and can be used to tailor change-detection monitoring to hypothesized geomorphic and vegetation changes in specific hydrogeomorphic settings.