Event Title

Development of a sediment budget to inform river management of the regulated Snake River in Grand Teton National Park, Wyoming

Presenter Information

Susannah Erwin

Location

ECC 303/305

Event Website

http://water.usu.edu/htm/conference/past-spring-runoff-conferences

Start Date

6-4-2007 11:35 AM

End Date

6-4-2007 11:55 AM

Description

Preliminary estimates of a sediment budget for the regulated Snake River in Grand Teton National Park (GTNP) suggest that only in years with large dam releases are Snake River flows capable of remobilizing all the sediment delivered by tributaries. Our preliminary estimates were based on calibrated bed load transport relations developed for two major tributaries to the Snake River, Pacific Creek and Buffalo Fork, and an uncalibrated relation developed for the main-stem Snake River. Flows on the Snake River in GTNP have been regulated by operations of Jackson Lake Dam (JLD) since 1906, with a significant change to the flow regime occurring in 1958 that lowered peak flows and elevated late summer flows. The Snake River in GTNP is distinct from many other river systems impacted by dams in that JLD disrupts the flow of water, but not the flow of sediment to the Snake River. Alleged changes in the rate and frequency of channel avulsion and floodplain formation caused by operations of JLD are ultimately tied to the magnitude of bed material delivery from tributaries and transport by the main-stem Snake River. In an effort to better understand and assess changes in channel form and habitat impacts resulting from JLD operations, we are constructing a sediment budget for the Snake River in GTNP. This paper focuses on one component of this larger research effort: developing sediment transport relations for Pacific Creek and Buffalo Fork. We measured bed load transport rates on both tributaries over a range of discharges in the spring and summer, 2006, using a Toutle River bed load sampler. We used these measurements to calibrate transport relations and estimated the flux of sediment entering the Snake River with these calibrated transport relations. Our preliminary main-stem sediment transport relation will be refined with measurements of bed load transport rates collected during the 2007 field season.

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Apr 6th, 11:35 AM Apr 6th, 11:55 AM

Development of a sediment budget to inform river management of the regulated Snake River in Grand Teton National Park, Wyoming

ECC 303/305

Preliminary estimates of a sediment budget for the regulated Snake River in Grand Teton National Park (GTNP) suggest that only in years with large dam releases are Snake River flows capable of remobilizing all the sediment delivered by tributaries. Our preliminary estimates were based on calibrated bed load transport relations developed for two major tributaries to the Snake River, Pacific Creek and Buffalo Fork, and an uncalibrated relation developed for the main-stem Snake River. Flows on the Snake River in GTNP have been regulated by operations of Jackson Lake Dam (JLD) since 1906, with a significant change to the flow regime occurring in 1958 that lowered peak flows and elevated late summer flows. The Snake River in GTNP is distinct from many other river systems impacted by dams in that JLD disrupts the flow of water, but not the flow of sediment to the Snake River. Alleged changes in the rate and frequency of channel avulsion and floodplain formation caused by operations of JLD are ultimately tied to the magnitude of bed material delivery from tributaries and transport by the main-stem Snake River. In an effort to better understand and assess changes in channel form and habitat impacts resulting from JLD operations, we are constructing a sediment budget for the Snake River in GTNP. This paper focuses on one component of this larger research effort: developing sediment transport relations for Pacific Creek and Buffalo Fork. We measured bed load transport rates on both tributaries over a range of discharges in the spring and summer, 2006, using a Toutle River bed load sampler. We used these measurements to calibrate transport relations and estimated the flux of sediment entering the Snake River with these calibrated transport relations. Our preliminary main-stem sediment transport relation will be refined with measurements of bed load transport rates collected during the 2007 field season.

http://digitalcommons.usu.edu/runoff/2007/AllAbstracts/35