Title

INVESTIGATING UPSTREAM CHANNEL RESPONSE TO DAM REMOVAL, BLACKFOOT RIVER, MT

Presentation Type

Presentation

Abstract

As dam removal becomes more accepted as an effective approach to river restoration, understanding the upstream channel geomorphic response is vital. This study is being conducted to examine upstream channel evolution of the Blackfoot River (BFR) in response to an 8-meter drop in base level that was caused by the 2008 removal of the Milltown Dam. This research is testing the hypothesis that geomorphic response will be more pronounced closest to the site of the dam with more incision occurring on the bed and this response decreasing upstream. For this study, longitudinal, cross section elevation and grain size data from 13 BFR sites will be collected: seven cross sections within the area influenced by Milltown Reservoir and six cross sections upstream. To quantify net geomorphic change, two variables are being investigated: (1) the change in grain size and, (2) the adjustment of channel geometry over a three-year period (2008-2011). Preliminary observations indicate that in addition to distance from the dam other geomorphic factors such as grain size and channel confinement also drive channel response. Long-term studies of upstream channel response to dam removals are rare. Results from this study will help increase understanding of this dam removal and can be applied to future dam remediation projects.

Category

Physical Sciences

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Apr 15th, 9:00 AM Apr 15th, 9:20 AM

INVESTIGATING UPSTREAM CHANNEL RESPONSE TO DAM REMOVAL, BLACKFOOT RIVER, MT

UC 327

As dam removal becomes more accepted as an effective approach to river restoration, understanding the upstream channel geomorphic response is vital. This study is being conducted to examine upstream channel evolution of the Blackfoot River (BFR) in response to an 8-meter drop in base level that was caused by the 2008 removal of the Milltown Dam. This research is testing the hypothesis that geomorphic response will be more pronounced closest to the site of the dam with more incision occurring on the bed and this response decreasing upstream. For this study, longitudinal, cross section elevation and grain size data from 13 BFR sites will be collected: seven cross sections within the area influenced by Milltown Reservoir and six cross sections upstream. To quantify net geomorphic change, two variables are being investigated: (1) the change in grain size and, (2) the adjustment of channel geometry over a three-year period (2008-2011). Preliminary observations indicate that in addition to distance from the dam other geomorphic factors such as grain size and channel confinement also drive channel response. Long-term studies of upstream channel response to dam removals are rare. Results from this study will help increase understanding of this dam removal and can be applied to future dam remediation projects.